Sunday, December 14, 2014

Myocardial perfusion imaging in diabetes

Myocardial perfusion imaging for evaluation of suspected ischemia and its relationship with glycemic control in South African subjects with diabetes mellitus.
This study found that diabetics were more likely to have abnormal myocardial perfusion than non-diabetics. In addition, a HgbA1c > = 7.0% was associated with a greater risk of having an abnormal perfusion scan compared to diabetics with a HgbA1c of < 7.0%.

Diabetes Metab Syndr Obes. 2014;7:545-552

Direct Imaging of Ischemia

Direct Myocardial Ischemia Imaging: a New Cardiovascular Nuclear Imaging Paradigm.
This review article discusses in depth how to image myocardial ischemia directly as an alternative to stress-rest myocardial perfusion imaging. Techniques include the use of radiolabeled fatty acids and 18F-FDG. Read More

Thursday, November 20, 2014

Long-term mortality after a normal nuclear SPECT exam

Long-term mortality following normal exercise myocardial perfusion SPECT according to coronary disease risk factors.
QUESTION: does a normal SPECT study carry the same prognosis among different patient sub-groups according to risk factors?

METHODS: 12,232 patients with a normal exercise SPECT-MPI scan were evaluated.

RESULTS: The all cause morality rate overall was 0.8%/year, but varied according the the presence of risk factors. Hypertension, smoking, diabetes, exercise capacity, dyspnea, obesity, higher resting heart rate, an abnormal ECG, LVH, atrial fibrillation, and LVEF < 45% were all predictors of increased mortality.

  • 0.2% per year among non-smokers exercising for >9 minutes with no hypertension or diabetes
  • 1.6% per year among patients exercising <6 minutes at least 2 of the following: hypertension, diabetes, or smoking.

CONCLUSIONS: Mortality risk varies with comorbidities and is not exclusively dependent upon nuclear SPECT imaging results. 

J Nucl Cardiol. 2014 Apr;21(2):341-50

COMMENT: isn't it great that we are able to modify at least one of the primary risk factors (smoking)? 

Friday, October 31, 2014

Is Appropriate Use Similar for Cardiology and Non-Cardiology Providers?

Utilization patterns of single-photon emission cardiac tomography myocardial perfusion imaging studies in a rural tertiary care setting.
BACKGROUND: Appropriate use criteria (AUC) for single-photon emission computed tomographic myocardial perfusion imaging (SPECT MPI) were revised in 2009 to include 15 new clinical scenarios.

OBJECTIVE: are the appropriate utilization rates of SPECT MPI imaging similar for cardiology and non cardiology providers?

METHODS: all SPECT MPI studies performed for over a 6-month period at our center were reviewed.

RESULTS: 88% of studies were classified as appropriate, 5.5% as inappropriate,  and 7% as uncertain. The ordering provider specialty did not show any relation with appropriateness of the test (P = 0.46).

CONCLUSIONS: A great majority of MPI studies are performed for appropriate indications regardless of ordering provider specialty.

Clin Cardiol. 2014 Feb;37(2):67-72

Monday, October 20, 2014

Ranolazine and SPECT Myocardial Perfusion Scans

BACKGROUND: Patients with angina relieved by ranolazine (RAN) and a normal SPECT myocardial perfusion scan present a dilemma. Should patients with angina relieved by RAN but a normal SPECT undergo angiography?

METHODS: a chart review was performed. Angiography was done on all the patients with complete angina relief taking RAN, as well as nonresponders whose anginal etiology could not be explained. Stenoses were considered flow-restrictive when more than 70% diameter stenosis is observed by quantitative angiography, or when 50 to 70%, fractional flow reserve (FFR) measured ≤0.80.

RESULTS: RAN relieved angina in 36 of 54 (67%) patients. For 25 of these 36 patients had stenoses ≥50% with 15 (60%) having 1 vessel disease; 9 (36%) having multivessel disease; and 1 (4%) having left main disease. 18 of the 25 (72%) patients had stenoses considered to be flow restrictive. Eight RAN non-responders with no explanation for angina had no obstructive disease on angiography.

CONCLUSION: angina relief by ranolazine helps identify an increased risk of flow-restrictive stenosis in patients with a negative SPECT myocardial perfusion scan. Patients with angina relief by ranolazine are likely to benefit from angiography.

COMMENT: SPECT and angiography do not represent the same thing. SPECT images physiology, and angiography images anatomy. While often the two agree, frequently obstructive disease is not associated with ischemia (e.g. good collateralization) and ischemic disease is not associated with obstruction (e.g. coronary artery spasm). Ranolazine is a partial fatty acid oxidation inhibitor.

Int J Angiol. 2014 Sep;23(3):165-70

Thursday, October 16, 2014

Can Low Grade Radiation Protect Against Cancer?

Surprising Research Finds Beneficial Effects of Low Level Radiation Exposure

Cancer is a heterogeneous disease characterized by uncontrolled cellular growth and multiplication. There are several risk factors associated with cancer, including smoking, inactivity, and a poor diet. However, the role of radiation exposure as a risk factor is unclear. We do know that sudden high doses of radiation, such as that experienced by people exposed to the atomic bomb blasts in Hiroshima and Nagasaki, increases cancer risk. But does all radiation increase the risk of cancer? Surprising evidence suggests that the opposite occurs, that low levels of radiation may actually protect against cancer by a process called radiation hormesis .
The best evidence for a beneficial effect of low level radiation comes from Asia. In Taiwan, approximately 25 years ago, recycled steel was accidentally contaminated with radioactive cobalt-60. This steel was used to build more than 180 buildings, and approximately 10,000 people occupied this buildings for about 10 to 20 years. The mean dose to the residents was approximately 13 mSv per year and the maximum dose was 160 mSv per year. For comparison purposes, the occupational limit for radiation workers in the U.S. is 50 mSv per year. The International Atomic Energy Agency sets the occupational limit at 20 mSv per year.
This unique research, made possible due to the accidental contamination of steel used to make apartment buildings, found that estimates of radiation risk from the International Commission on Radiological Protection were completely wrong. Compared to residents of nearby apartment buildings, that did not contain the radioactive cobalt-50 contamination, the people exposed to low level radiation had greatly reduced cancer deaths and congenital malformations. The cancer death rate among those exposed to low level radiation was only 3% of the rate of the general public. Put another way, the general public was more than 30 times more likely to die of cancer than the people living in the apartment buildings that exposed them to low level radiation over many years. Furthermore, the congenital malformation rate of the radiation exposed residents was 6.5% of the rate of the general public. The general public was more than 15 times more likely to have a child with congenital malformations compared to the radiation exposed residents.
This is strong evidence that a low level of radiation exposure has a beneficial health effect in terms of cancer and congenital malformations. Furthermore, this research is from real world data, not conjecture or theoretical mathematical models.
Based upon this promising research, and similar findings from other epidemiologic studies, some scientists have proposed that further human experiments be carried out, perhaps in nursing homes. Of course, such research would require full consent, Institutional Review Board oversight, and full disclosure to all individuals involved. But if death from cancer can be reduced by a factor of 30, certainly more research into this possibility is needed.
Current radiation hysteria and the linear no-threshold hypothesis do not appear to be based upon valid, scientific evidence. It is time to move out of the dark ages when it comes to radiation, and insist that policy decisions be based upon real world evidence.
REFERENCE: Chen WL et al. Is chronic radiation an effective prophylaxis against cancer? J Amer Phys Surg 2004;9(1):6-10.

The PET/CT Scanner I helped install for Johns Hopkins International

Published by Tom Heston MD 3/24/2012
Tom Heston MD is a Johns Hopkins trained physician who practices clinical medicine in the Pacific Northwest.  

Saturday, March 29, 2014

Assessment of global myocardial perfusion reserve using cardiovascular magnetic resonance of coronary sinus flow at 3 Tesla.

BACKGROUND: Despite increasing clinical use, there is limited data regarding regadenoson in stress perfusion cardiovascular magnetic resonance (CMR). In particular, given its long half-life the optimal stress protocol remains unclear. Although Myocardial Perfusion Reserve (MPR) may provide additive prognostic information, current techniques for its measurement are cumbersome and challenging for routine clinical practice.The aims of this study were: 1) To determine the feasibility of MPR quantification during regadenoson stress CMR by measurement of Coronary Sinus (CS) flow; and 2) to investigate the role of aminophylline reversal during regadenoson stress-CMR.
METHODS: 117 consecutive patients with possible myocardial ischemia were prospectively enrolled. Perfusion imaging was performed at 1 minute and 15 minutes after administration of 0.4 mg regadenoson. A subgroup of 41 patients was given aminophylline (100 mg) after stress images were acquired. CS flow was measured using phase-contrast imaging at baseline (pre CS flow), and immediately after the stress (peak CS flow) and rest (post CS flow) perfusion images.
RESULTS: CS flow measurements were obtained in 92% of patients with no adverse events. MPR was significantly underestimated when calculated as peak CS flow/post CS flow as compared to peak CS flow/pre CS flow (2.43 +/- 0.20 vs. 3.28 +/- 0.32, p = 0.03). This difference was abolished when aminophylline was administered (3.35 +/- 0.44 vs. 3.30 +/- 0.52, p = 0.95). Impaired MPR (peak CS flow/pre CS flow <2) was associated with advanced age, diabetes, current smoking and higher Framingham risk score.
CONCLUSIONS: Regadenoson stress CMR with MPR measurement from CS flow can be successfully performed in most patients. This measurement of MPR appears practical to perform in the clinical setting. Residual hyperemia is still present even 15 minutes after regadenoson administration, at the time of resting-perfusion acquisition, and is completely reversed by aminophylline. Our findings suggest routine aminophylline administration may be required when performing stress CMR with regadenoson.

J Cardiovasc Magn Reson. 2014 Mar 27;16(1):24

Friday, March 21, 2014

Twenty four hour imaging delay improves viability detection by Tl-201 myocardial perfusion scintigraphy.

OBJECTIVE: Since twenty-four-hour imaging by Tl-201 myocardial perfusion scintigraphy has been introduced as an effective additional procedure, the aim of this study was to compare this method's result with only rest redistribution procedure in the diagnosis of myocardial viability.
METHODS: Thirty patients (Seven female, 23 male; mean: 59.8 ± 10.7, 55.8-63.8 years old) with diagnosis of coronary artery disease were involved in this study. All patients had anamnesis of previous myocardial infarction and/or total occlusion of any main artery in the coronary angiography. Myocardial perfusion scintigraphy with Tl-201 with rest four hour (early) redistribution and 24 hour delayed redistribution protocol were performed to all of the patients. The images were evaluated according to 17 segment basis by an experienced nuclear medicine physician and improvement of a segment by visual interpretation was considered as viable myocardial tissue.
RESULTS: Viability was found at 52 segments in the early redistribution images and additional 18 segments in the 24 hour delayed redistribution images on segment basis in the evaluation of 510 segments of 30 patients. On per patient basis, among the 26 patients who had viable tissue, 14 (54%) had additional improvement in 24 hour delayed images. Three (12%) patients had viable tissue in only 24 hour delayed images.
CONCLUSION: Delayed imaging in Tl-201 MPS is a necessary application for the evaluation of viable tissue according to considerable number of patients with additional improvement in 24 hour images in our study, which is restricted to the patients with myocardial infarct.

Rev Bras Cir Cardiovasc. 2013 Dec;28(4):498-503

Wednesday, March 19, 2014

Experience of low-dose aminophylline use to relieve minor adverse effects of dipyridamole

BACKGROUND: aminophylline is widely used to reverse dipyridamole-related adverse effects during stress myocardial perfusion imaging (MPI).

METHODS: 2,250 consecutive patients were evaluated.

RESULTS: No severe adverse events were observed. Low-dose (25 mg) aminophylline relieved symptoms in 98.8% of patients with mild adverse events. An additional 25 mg aminophylline reversed the moderate adverse events.

CONCLUSION: aminophylline at 25 mg IV is sufficient to relieve nearly all dipyridamole-related adverse events observed during stress MPI.

J Nucl Cardiol. 2014 Mar 14

Monday, March 17, 2014

Inappropriate utilization of SPECT myocardial perfusion imaging on the USA-Mexico border.

BACKGROUND: The ASNC published revised "Appropriate Use Criteria" for SPECT MPI in 2009.

METHODS: 420 SPECT MPI studies were evaluated.

RESULTS: 86% were appropriate and 14% inappropriate. Younger females were more likely to have an inappropriate test. Diabetics and patients with chest pain were less likely to have an inappropriate test. Community primary care providers were less likely than community cardiologists to order an inapproprate test.

CONCLUSIONS: young women are more likely to have an inappropriate nuclear myocardial perfusion imaging scan compared to other demographic groups. Cardiologists were more likely to order inappropriate tests compared to primary care providers.

J Nucl Cardiol. 2014 Mar 14;

Friday, March 14, 2014

Optimisation of reconstruction-reprojection-based motion correction for cardiac SPECT.

OBJECTIVE: Cardiac motion is a challenging cause of image artefacts

METHODS: Two slightly different implementations of reconstruction-reprojection-based motion correction techniques were optimised for effective, good-quality motion correction and then compared with each other. The first of these methods (Method 1) was the traditional reconstruction-reprojection motion correction algorithm, where the motion correction is done in projection space, whereas the second algorithm (Method 2) performed motion correction in reconstruction space.

RESULTS: Method 2 performed slightly better overall than Method 1, but the difference between the two implementations was small. The execution time for Method 2 was much longer than for Method 1, which limits its clinical usefulness. The mutual information cost function gave clearly the best results for all three motion sets for both correction methods. Three iterations were sufficient for a good quality correction using Method 1.

CONCLUSIONS: The traditional reconstruction-reprojection-based method with three update iterations and mutual information cost function is a good option for motion correction in clinical myocardial perfusion SPECT.

Ann Nucl Med. 2014 Mar 6

Thursday, March 13, 2014

Myocardial Tissue Perfusion Predicts the Evolution of Fragmented QRS

BACKGROUND: Fragmented QRS complex (fQRS) is associated with worse outcomes in several cardiovascular conditions.

METHODS: 401 consecutive patients with STEMI underwent primary PCI. Patients were categorized into two subgroups according to persistence or new-onset of fQRS (Group 1) and absence or resolution of fQRS (Group 2).

RESULTS: Patients in group 1 showed older age, higher rate of smoking, lower HDL-cholesterol, lower LVEF, higher angina-to-door time, higher TIMI frame count, and high rate of patients with MBG <3 compared to patients with group 2 (P < 0.05). In correlation analysis, LVEF showed positive correlation with myocardial blush grade (MBG, r = 0.448, P < 0.001) and negative correlation with the number of leads with fQRS (r = -0.335, P < 0.001). In multivariate regression analysis, new-onset or persistance of fQRS after primary PCI is significantly associated with MBG, peak CK-MBl, pre-PCI fQRS, and smoking.

CONCLUSION: Our findings showed that despite complete ST-segment resolution in all patients, fQRS is independently associated with impaired microvascular myocardial perfusion. So, fQRS, as a simple and easily available noninvasive marker, may be useful in stratification of high-risk patients with increased extent of infarcted myocardium who underwent primary PCI.

Ann Noninvasive Electrocardiol. 2014 Mar 4

COMMENT: not surprisingly, smoking was associated with higher risk

Tuesday, March 11, 2014

The use of a learning community and online evaluation of utilization for SPECT myocardial perfusion imaging.

This study found that a self-directed quality improvement web based community in conjunction with a software quality improvement program was able to reduce "inappropriate" ordering of tests by 50% within a year. JACC Cardiovasc Imaging. 2013 Jul;6(7):823-9

COMMENT: it appears from this study that all that's needed nowadays is a computer to decide what tests you need. Why even see a doctor? 

Sunday, March 9, 2014

Evaluation of Suspected Ischemic Heart Disease in Symptomatic Women.

Evaluation of Suspected Ischemic Heart Disease in Symptomatic Women.
Can J Cardiol. 2013 Sep 28;
Authors: Shaw LJ, Tandon S, Rosen S, Mieres JH

There is a wealth of evidence about the role of a variety of diagnostic testing modalities to define coronary artery disease (CAD) risk in women presenting for evaluation of suspected myocardial ischemia. The exercise electrocardiogram (ECG) is the core index procedure, which can define risk in women capable of performing maximal exercise. Stress imaging, using echocardiography or myocardial perfusion single-photon emission computed tomography/positron emission tomography, is useful for symptomatic women with an abnormal resting ECG or for those who are functionally disabled. For women with low-risk stress imaging findings, there is a very low risk of CAD events, usually < 1%. There is a gradient relationship between the extent and severity of inducible abnormalities and CAD event risk. Women at high risk are those defined as having moderate to severely abnormal wall motion or abnormal perfusion imaging findings. In addition to stress imaging, the evidence of the relationship between CAD extent and severity and prognosis has been clearly defined with coronary computed tomographic angiography. In women, prognosis for those with mild but nonobstructive CAD is higher when compared with those without any CAD. The current evidence base clearly supports that women presenting with chest pain can benefit from one of the commonly applied diagnostic testing modalities.

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Assessing clinical impact of myocardial perfusion studies: ischemia or other prognostic indicators?

Assessing clinical impact of myocardial perfusion studies: ischemia or other prognostic indicators?
Curr Cardiol Rep. 2014 Apr;16(4):465
Authors: Miller TD, Askew JW, Herrmann J

One of the major strengths of nuclear myocardial perfusion imaging (MPI) is the robust prognostic databases from observational studies demonstrating significantly different outcomes in patients with low-risk vs high-risk scans. The severity of the MPI defect can be semi-quantitated using the summed stress score (SSS) and summed difference score (SDS). SSS is more strongly associated with mortality, whereas SDS is the better predictor of subsequent coronary angiography and revascularization. The strength of MPI variables as prognostic indicators decreases when adjusted for prognostically important clinical and stress test variables. Nonetheless, most studies of general patient populations have demonstrated that MPI adds incremental prognostic value to clinical and stress test information. In contrast to these positive results from observational studies, the application of MPI ischemia as a treatment guide in several recent trials (DIAD, WOMEN, COURAGE, BARI 2D, STICH) has largely failed to identify patient subsets with improved outcome. This issue will continue to be investigated in the ongoing PROMISE and ISCHEMIA trials.

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Friday, March 7, 2014

Advanced imaging of cardiac sarcoidosis.

Advanced imaging of cardiac sarcoidosis.
J Nucl Med. 2014 Jan;55(1):99-106
Authors: Schatka I, Bengel FM

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Cardiac involvement may occur, leading to an adverse outcome. Although early treatment to improve morbidity and mortality is desirable, sensitive and accurate detection of cardiac sarcoidosis remains a challenge. Accordingly, interest in the use of advanced imaging such as cardiac MR and PET with (18)F-FDG is increasing in order to refine the clinical workup. Although the field is still facing challenges and uncertainties, this article presents a summary of clinical background and the current state of diagnostic modalities and treatment of cardiac sarcoidosis.

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Assessment of myocardial perfusion with MRI using a modified dual bolus method.

Assessment of myocardial perfusion with MRI using a modified dual bolus method.
Physiol Meas. 2014 Feb 27;35(4):533-547
Authors: Husso M, Sipola P, Kuittinen T, Manninen H, Vainio P, Hartikainen J, Saarakkala S, Töyräs J, Kuikka J

Quantification of regional myocardial blood flow (rMBF) with first-pass magnetic resonance imaging (FP-MRI) requires two contrast agent injections (dual bolus technique), inducing error in the determined rMBF if the injections differ. We hypothesize that using input and residue curves of the same injection would be more reliable. We aim to introduce and evaluate a novel method to correct the high concentration arterial input function (AIF) for determination of rMBF. Sixteen patients with non-Hodgkin's lymphoma were examined before and after chemotherapy. The input function was solved by correcting initial high concentration AIF using the ratio of low and high contrast AIF areas, normalized by corresponding heart rates (modified dual bolus method). For comparison, the scaled low contrast AIF was used as an input function (dual bolus method). Unidirectional transfer coefficient K(trans) was calculated using both methods. K(trans)-values determined with the dual bolus (0.81 ± 0.32 ml g(-1) min(-1)) and modified dual bolus (0.77 ± 0.42 ml g(-1) min(-1)) methods were in agreement (p = 0.21). Mean K(trans)-values increased from 0.76 ± 0.43 to 0.89 ± 0.55 ml g(-1) min(-1) after chemotherapy (p = 0.17). The modified dual bolus technique agrees with the dual bolus technique (R2 = 0.899) when the low and high contrast injections are similar. However, when this is not the case, the modified dual bolus technique may be more reliable.

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Assessing the Prognostic Implications of Myocardial Perfusion Studies: Identification of Patients at Risk vs Patients who May Benefit from Intervention?

Assessing the Prognostic Implications of Myocardial Perfusion Studies: Identification of Patients at Risk vs Patients who May Benefit from Intervention?
Curr Cardiol Rep. 2014 Apr;16(4):472
Authors: Cremer P, Hachamovitch R

Stress myocardial perfusion imaging (MPI) has a well-established role in improving risk stratification. Recent analyses, compared with older data, suggest that the yield of stress MPI has decreased. In part, this trend relates to testing patients with heterogeneous, but improved, risk factor modification. In this setting, positron emission tomography with myocardial flow reserve enhances risk stratification as it reflects the end result of atherosclerosis. Recent studies have also emphasized the clinical impact of incremental risk stratification by assessing net reclassification improvement (NRI). Previous retrospective studies have favored an ischemic threshold to select patients that benefit from revascularization, but this finding has not been corroborated in randomized trials. However, no large randomized trial has directly tested a strategy of revascularization for patients with at least a moderate amount of ischemia at risk. Unfortunately, even when faced with a significantly abnormal MPI result, subsequent action is too often absent.

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Quantitative three-dimensional cardiovascular magnetic resonance myocardial perfusion imaging in systole and diastole.

Quantitative three-dimensional cardiovascular magnetic resonance myocardial perfusion imaging in systole and diastole.
J Cardiovasc Magn Reson. 2014 Feb 24;16(1):19
Authors: Motwani M, Kidambi A, Sourbron S, Fairbairn TA, Uddin A, Kozerke S, Greenwood JP, Plein S

BACKGROUND: Two-dimensional (2D) perfusion cardiovascular magnetic resonance (CMR) remains limited by a lack of complete myocardial coverage. Three-dimensional (3D) perfusion CMR addresses this limitation and has recently been shown to be clinically feasible. However, the feasibility and potential clinical utility of quantitative 3D perfusion measurements, as already shown with 2D-perfusion CMR and positron emission tomography, has yet to be evaluated. The influence of systolic or diastolic acquisition on MBF estimates, diagnostic accuracy and image quality is also unknown for 3D-perfusion CMR. The purpose of this study was to establish the feasibility of quantitative 3D-perfusion CMR for the detection of coronary artery disease (CAD) and to compare systolic and diastolic estimates of myocardial blood flow (MBF).
METHODS: Thirty-five patients underwent 3D-perfusion CMR with data acquired at both end-systole and mid-diastole. MBF and myocardial perfusion reserve (MPR) were estimated on a per patient and per territory basis by Fermi-constrained deconvolution. Significant CAD was defined as stenosis >=70% on quantitative coronary angiography.
RESULTS: Twenty patients had significant CAD (involving 38 out of 105 territories). Stress MBF and MPR had a high diagnostic accuracy for the detection of CAD in both systole (area under curve [AUC]: 0.95 and 0.92, respectively) and diastole (AUC: 0.95 and 0.94). There were no significant differences in the AUCs between systole and diastole (p values >0.05). At stress, diastolic MBF estimates were significantly greater than systolic estimates (no CAD: 3.21 +/- 0.50 vs. 2.75 +/- 0.42 ml/g/min, p < 0.0001; CAD: 2.13 +/- 0.45 vs. 1.98 +/- 0.41 ml/g/min, p < 0.0001); but at rest, there were no significant differences (p values >0.05). Image quality was higher in systole than diastole (median score 3 vs. 2, p = 0.002).
CONCLUSIONS: Quantitative 3D-perfusion CMR is feasible. Estimates of MBF are significantly different for systole and diastole at stress but diagnostic accuracy to detect CAD is high for both cardiac phases. Better image quality suggests that systolic data acquisition may be preferable.

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Wednesday, March 5, 2014

Noncalcified Coronary Plaque Volumes in Healthy People with a Family History of Early-Onset Coronary Artery Disease.

Noncalcified Coronary Plaque Volumes in Healthy People with a Family History of Early-Onset Coronary Artery Disease.
Circ Cardiovasc Imaging. 2014 Feb 27;
Authors: Kral BG, Becker LC, Vaidya D, Yanek LR, Qayyum R, Zimmerman SL, Dey D, Berman DS, Moy TF, Fishman EK, Becker DM

BACKGROUND: -Although age and sex distributions of calcified plaque (CCP) have been well described in the general population, noncalcified plaque (NCP) distributions remain unknown. This is important because NCP is a putative precursor for clinical CAD and could serve as a sentinel for aggressive primary prevention, especially in higher risk populations. We examined the distributions of NCP and CCP in healthy 30-74 year old individuals from families with early-onset coronary artery disease (CAD).
METHODS AND RESULTS: -Participants in the GeneSTAR family study (N=805), mean age 51.1 ± 10.8 years, 56% female, were screened for CAD risk factors and for coronary plaque using dual-source CT angiography. Plaque volumes (mm(3)) were quantified using a validated automated method. The prevalence of coronary plaque was 57.8% in males and 35.8% in females (p<0.0001). NCP volume increased with age (p<0.001) and was higher in males than females (p<0.001). Although NCP, as a percent of total plaque, was inversely related to age (p<0.01), NCP accounted for most of the total plaque volume at all ages, especially in males and females <55 years (>70% and >80%, respectively). Higher Framingham risk was associated with the number of affected vessels (p<0.01) but 44% of males and 20.8% of females considered intermediate risk had left main and/or 3-vessel disease involvement.
CONCLUSIONS: -The majority of coronary plaque was noncalcified, particularly in younger individuals. These findings support the importance of assessing family history and suggest that early primary prevention interventions may be warranted at younger ages in families with early onset CAD.

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Monday, March 3, 2014

Correlation between transient ischemic dilatation (TID) and coronary artery disease in Saudi male patients.

Correlation between transient ischemic dilatation (TID) and coronary artery disease in Saudi male patients.
J Saudi Heart Assoc. 2014 Jan;26(1):1-5
Authors: Aldhilan A, Syed GM, Suleiman I, Al Zaibag M, Fielding H

OBJECTIVE: A high transient ischemic dilatation ratio (TID) for the left ventricle (LV) from a gated myocardial perfusion imaging (G-MPI) study is widely believed to be associated with significant coronary artery disease (CAD). We have investigated the relationship between TID and CAD for our male Saudi Arabian patient population.
METHODS: In this retrospective study, all male Saudi Arabian patients who underwent a two-day G-MPI study using Tc99m MIBI during the year 2011 having a TID ⩾ 1.20 were included. Quantitative perfusion and gated parameters were obtained using Cedar Sinai's AutoQuant software version 3.0, 2003, Means of summed stress scores, summed rest scores and summed difference scores (SSS, SRS, SDS, respectively), stress and rest ejection fraction (EF) were calculated. Visual interpretation was performed to classify the perfusion as normal, fixed, mixed (fixed and reversible defects), single reversible or multiple reversible defects. Coronary angiograms were assessed as normal with no CAD, single vessel, two-vessel or three-vessel disease. Correlations between the TID and other parameters were studied using analysis of variance (ANOVA) with IBM-SPSS version 20.
RESULTS: A total of 52 male patients had a high TID of ⩾1.20 (mean 1.30 ± 0.13). Ten patients had a SSS of 0-3 and 16 were classified as normal by visual assessment. Stress EF (mean 50.4 ± 12%) was lower than the rest EF (mean 56.6 ± 12.8%) with the difference being statistically significant (Students paired t-test, p = 0.001). Angiography results were available in 44 patients, 3 having a normal angiogram, 24 having three vessel disease, 7 having two vessel disease and 10 having one vessel disease. Five patients with normal perfusion and SSS = 0-3 had CAD as seen on a coronary angiography. CAD on coronary angiography showed a significant correlation with perfusion abnormalities as assessed by visual interpretation (p = 0.002). TID showed a significantly correlation with both perfusion abnormalities (p = 0.009), as assessed by visual interpretation, and with Summed difference scores, SDS (p = 0.000).
CONCLUSION: A high TID on G-MPI was a very sensitive indicator of significant CAD. In patients with normal perfusion and high TID further workup is warranted.

24578594 [PubMed]
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Sites of latest mechanical activation as assessed by SPECT myocardial perfusion imaging in ischemic and dilated cardiomyopathy patients with LBBB.

Sites of latest mechanical activation as assessed by SPECT myocardial perfusion imaging in ischemic and dilated cardiomyopathy patients with LBBB.
Eur J Nucl Med Mol Imaging. 2014 Feb 28;
Authors: Lin X, Xu H, Zhao X, Chen J

OBJECTIVE: Sites of latest mechanical activation (SOLA) have been recognized as optimal left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT). This study was aimed to investigate SOLA in ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) patients with left bundle branch block (LBBB).
METHODS: Sixty-four consecutive LBBB patients (47 DCM, 17 ICM), who met the standard indications for CRT and underwent resting SPECT myocardial perfusion imaging (MPI), were selected. Phase analysis was used to assess LV dyssynchrony and SOLA. The Emory Cardiac Toolbox was used to measure perfusion defects. LV dyssynchrony and SOLA were compared between the DCM patients with wide (≥150 ms) and moderate (120-150 ms) QRS durations (QRSd). The relationship between SOLA and perfusion defects was analyzed in the ICM patients.
RESULTS: The DCM patients with wide QRSd had significantly more LV dyssynchrony than those with moderate QRSd. Lateral SOLA were significantly more frequent in the DCM patients with wide QRSd than those with moderate QRSd (96 % vs. 62 %, p = 0.010). In the ICM patients, SOLA were either in the scar segments (82 %) or in the segments immediately adjacent to the scar segments (18 %), regardless of QRSd.
CONCLUSION: Lateral SOLA were more frequent in the DCM patients with wide QRSd than those with moderate QRSd. Such relationship was not observed in the ICM patients, where SOLA were associated with scar location rather than QRSd. These findings support the use of SPECT MPI to aid the selection of potential CRT responders and guide LV lead placement.

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Computed Tomography Assessment of Hemodynamic Significance of Coronary Artery Disease: CT Perfusion, Contrast Gradients by Coronary CTA, and Fractional Flow Reserve Review.

Computed Tomography Assessment of Hemodynamic Significance of Coronary Artery Disease: CT Perfusion, Contrast Gradients by Coronary CTA, and Fractional Flow Reserve Review.
J Thorac Imaging. 2014 Feb 26;
Authors: Loewe C, Stadler A

The need for functional estimation of the relevance of stenosis to guide appropriate treatment in coronary artery disease has recently been shown. Invasive coronary angiography (CA) with invasive measurement of the pressure gradient in patients with coronary stenoses becomes the method of choice for treatment decision-making in invasive cardiology. Coronary computed tomography angiography (CCTA) was established several years ago as a noninvasive alternative to invasive CA; it is used primarily to exclude coronary artery disease and has shown a very high negative predictive value in this regard. During the last several years, in an effort to obtain functional information, CCTA has received much attention. The rationale for this is that with the functional information provided by CT, the positive predictive value for "relevant" stenoses should be improved. In this article, the history and limitations of anatomic grading of coronary stenoses will be discussed. Furthermore, shifts in the treatment paradigm in modern cardiology will be introduced, as well as an overview of the currently used invasive methods to assess the "relevance" of stenosis. The current role and still-existing limitations of CCTA, as well as the systematic problems in comparing CA and CCTA, are addressed. As CCTA is a highly innovative technique, new innovations are currently under clinical evaluation, including myocardial perfusion imaging, attenuation gradient measurement, and assessment of fractional flow reserve with CT. This review article will mainly focus on the technical background of these techniques and the status of their clinical implementation and will attempt to provide some suppositions about the possible future role of these new innovations.

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Testosterone deficiency syndrome and cardiovascular health: An assessment of beliefs, knowledge and practice patterns of general practitioners and cardiologists in Victoria, BC.

Testosterone deficiency syndrome and cardiovascular health: An assessment of beliefs, knowledge and practice patterns of general practitioners and cardiologists in Victoria, BC.
Can Urol Assoc J. 2014 Jan;8(1-2):30-3
Authors: Wallis CJ, Brotherhood H, Pommerville PJ

INTRODUCTION: Testosterone deficiency syndrome (TDS) has been shown to be an independent cardiovascular risk factor and a predisposing factor for metabolic syndrome. As general practitioners and cardiologists primarily care for these patients, we sought to assess their knowledge, beliefs and practice patterns with respect to TDS and cardiac health.
METHODS: We distributed a questionnaire to all 20 cardiologists and a cohort of 128 family practitioners in Victoria, British Columbia. Of the 13 questions, 10 assessed knowledge and beliefs on TDS and 3 assessed current practice patterns.
RESULTS: Most respondents believed that TDS is a medical condition (66.7%) and could negatively affect body composition (62%), but a similar majority was unsure whether it was a cardiac risk factor (66.7%). While most believed that testosterone replacement therapy (TRT) could improve exercise tolerance (62%), most were unsure if it was beneficial in cardiac patients. Cardiologists were significantly less likely to believe that TRT was beneficial in preventing recurrent myocardial infarction and improving myocardial perfusion (p = 0.0133, 0.00186, respectively). The vast majority (88%) did not screen cardiac patients for TDS. If a patient was identified as having TDS, only10% of those surveyed would refer these patients to a urologist.
CONCLUSION: Despite its prevalence in cardiac patients, TDS is not well-understood by general practitioners and cardiologists; they lack knowledge on its deleterious cardiovascular effects. In their role as men's health advocates, urologists should educate our colleagues regarding the correlation between TDS and cardiovascular mortality and risk factors. Limitations of this study include small sample size and restricted geographic scope.

24578740 [PubMed]
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Combined Supine and Prone Myocardial Perfusion Single-Photon Emission Computed Tomography With a Cadmium Zinc Telluride Camera for Detection of Coronary Artery Disease.

Combined Supine and Prone Myocardial Perfusion Single-Photon Emission Computed Tomography With a Cadmium Zinc Telluride Camera for Detection of Coronary Artery Disease.
Circ J. 2014 Feb 25;
Authors: Nishiyama Y, Miyagawa M, Kawaguchi N, Nakamura M, Kido T, Kurata A, Kido T, Ogimoto A, Higaki J, Mochizuki T

Background: Myocardial perfusion SPECT (MPS) traditionally requires the patient to be in the supine position, but diaphragmatic attenuation of the inferior wall reduces test specificity. The aim of this study was to assess the feasibility of combined MPS in the supine and prone positions using a novel cadmium zinc telluride (CZT) camera. Methods and Results: A total of 276 consecutive patients with suspected/known coronary artery disease (CAD) who underwent single-day (99m)Tc-tetrofosmin or (99m)Tc-sestamibi stress/rest CZT SPECT, were enrolled in the study. Seventy-six underwent coronary angiography. Five-minute scan in the supine (S) position and thereafter in the prone (P) position produced images that were visually interpreted to obtain summed stress (SSS) and rest (SRS) scores. A combined stress score (C-SSS) was calculated by grouping anterior perfusion defects observed during supine imaging with inferior half segments observed during prone imaging. The SSS for the supine, prone, and combined protocols were 9±8, 7±8, and 7±8, respectively (P<0.0001). The SRS were 5±8, 4±7, and 6±7, respectively (P=0.005). The area under the ROC curve for the S-SSS, P-SSS, and C-SSS scores was 0.815 (95% CI: 0.713-0.917), 0.813 (0.711-0.914), and 0.872 (0.783-0.961), respectively. Corresponding sensitivities and specificities for detecting CAD were 87% and 50%, 80% and 77%, and 85% and 82%, respectively. C-SSS had significantly better specificity and accuracy than S-SSS (P<0.05). Conclusions: Combined imaging with a CZT camera is suitable for routine clinical MPS and provides greater diagnostic accuracy than supine imaging alone.

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Friday, February 28, 2014

Left atrial volume index: relation to long-term clinical outcome in type 2 diabetes.

Left atrial volume index: relation to long-term clinical outcome in type 2 diabetes.
J Am Coll Cardiol. 2013 Dec 24;62(25):2416-21
Authors: Poulsen MK, Dahl JS, Henriksen JE, Hey TM, Høilund-Carlsen PF, Beck-Nielsen H, Møller JE

OBJECTIVES: The study sought to determine the prognostic importance of left atrial (LA) dilation in patients with type 2 diabetes mellitus (T2DM) and no history of cardiovascular disease (CVD).
BACKGROUND: T2DM is associated with the development of CVD, and morphological changes in the heart may appear before symptoms arise.
METHODS: A total of 305 T2DM patients without known CVD referred to a diabetes clinic were included consecutively (age 58.6 ± 11.3 years, diabetes duration 2.0 [interquartile range: 0 to 6.0] years). Each patient underwent a comprehensive echocardiogram and a myocardial perfusion scintigraphy (MPS) at inclusion. Patients were divided according to left atrial volume index (LAVi) ≥32 ml/m(2). Patients were followed for median of 5.6 (interquartile range: 5.1 to 6.1) years for the occurrence of major cardiac events and death.
RESULTS: LAVi ≥32 ml/m(2) was found in 105 patients (34%). During follow-up, 60 patients (20%) experienced the composite endpoint, of whom 28 (9%) died. Patients with LAVi ≥32 ml/m(2) had a significantly higher cardiac event rate and death rate (p < 0.001 and p = 0.002, respectively). Univariate predictors of the composite endpoint were age, hypertension, left ventricular diastolic function, E/e'septum-ratio and LAVi ≥32 ml/m(2); however, myocardial ischemia on MPS was not a predictor. When adjusting for age and hypertension, only LAVi ≥32 ml/m(2) was a predictor of the composite endpoint (hazard ratio: 1.82 [95% confidence interval: 1.08 to 3.07], p = 0.024).
CONCLUSIONS: Increased LAVi was an independent and incremental predictor of cardiovascular morbidity and mortality in T2DM patients with no history of CVD. (Presence of Macrovascular Disease in Type 2 Diabetes Mellitus; NCT00298844).

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Thursday, February 27, 2014

Prognostic Value of PET Myocardial Perfusion Imaging in Obese Patients.

Prognostic Value of PET Myocardial Perfusion Imaging in Obese Patients.
JACC Cardiovasc Imaging. 2014 Feb 12;
Authors: Chow BJ, Dorbala S, Di Carli MF, Merhige ME, Williams BA, Veledar E, Min JK, Pencina MJ, Yam Y, Chen L, Anand SP, Ruddy TD, Berman DS, Shaw LJ, Beanlands RS

OBJECTIVES: This study sought to determine and compare the prognostic and incremental value of positron emission tomography (PET) in normal, overweight, and obese patients.
BACKGROUND: Cardiac rubidium 82 (Rb-82) PET is increasingly being used for myocardial perfusion imaging (MPI). A strength of PET is its accurate attenuation correction, thereby potentially improving its diagnostic accuracy in obese patients. The prognostic value of PET in obese patients has not been well studied.
METHODS: A total of 7,061 patients who had undergone Rb-82 PET MPI were entered into a multicenter observational registry. All patients underwent pharmacologic Rb-82 PET and were followed for cardiac death and all-cause mortality. Based on body mass index (BMI), patients were categorized as normal (<25 kg/m(2)), overweight (25 to 29.9 kg/m(2)), or obese (≥30 kg/m(2)). Using a 17-segment model and 5-point scoring system, the percentage of abnormal myocardium was calculated for stress and rest patients categorized as normal (0%), mild (0.1% to 9.9%), moderate (10% to 19.9%), and severe (≥20%).
RESULTS: A total of 6,037 patients were followed for cardiac death (median: 2.2 years) and the mean BMI was 30.5 ± 7.4 kg/m(2). A total of 169 cardiac deaths were observed. PET MPI demonstrated independent and incremental prognostic value over BMI. Normal PET MPI conferred an excellent prognosis with very low annual cardiac death rates in normal (0.38%), overweight (0.43%), and obese (0.15%) patients. As well, both moderately and severe obese patients with a normal PET MPI had excellent prognosis (0.20% and 0.10%, respectively). The net reclassification improvement of PET was 0.46 (95% confidence interval [CI]: 0.31 to 0.61), and appeared similar in the moderately and severe obese patients which were 0.44 (95% CI: 0.12 to 0.76) and 0.63 (95% CI: 0.27 to 0.98), respectively.
CONCLUSIONS: Rb-82 PET has incremental prognostic value in all patients irrespective of BMI. In the obese population, where other modalities may have reduced diagnostic accuracy, cardiac PET appears to be a promising noninvasive modality with prognostic value.

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Can left ventricular parameters examined by gated myocardial perfusion scintigraphy and strain echocardiography be prognostic factors for major adverse cardiac events?

Can left ventricular parameters examined by gated myocardial perfusion scintigraphy and strain echocardiography be prognostic factors for major adverse cardiac events?
Hell J Nucl Med. 2014 Feb 21;
Authors: Karacavus S, Celik A, Tutus A, Kula M, Oguzhan A, Kalay N

Assessment of left ventricular (LV) function in patients with myocardial infarction (MI) provide useful diagnostic and prognostic information. Up to date, single photon emission tomography (SPET), positron emission tomography (PET), multidetector computed tomographic angiography, echocardiography (EC) and magnetic resonance imaging (MRI), have been used to examine LV parameters. However, due to limitations of some imaging methods, new studies are directed to improve myocardium function evaluation. In conclusion, SEC and GSPET can be applied to semi-quantitatively assess LVEF and regional wall motion abnormalities in a noninvasive manner. These techniques can provide strong diagnostic and prognostic information related to anterior myocardial infarction. In addition to this, nitrate enhanced GSPET allows to identify stunning and hibernating myocardium. New methods of reconstruction on GSPET systems will better improve image quality using lower count rates.

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Monday, February 24, 2014

Coronary sinus filling time: a novel method to assess microcirculatory function in patients with angina and normal coronaries.

Coronary sinus filling time: a novel method to assess microcirculatory function in patients with angina and normal coronaries.
Indian Heart J. 2013 Mar-Apr;65(2):142-6
Authors: Haridasan V, Nandan D, Raju D, Rajesh GN, Sajeev CG, Vinayakumar D, Muneer K, Babu K, Krishnan MN

OBJECTIVE: Dysfunction of the coronary microcirculation is considered as one of the factors responsible for symptoms and abnormal stress tests in patients with angina and normal coronaries (syndrome X). We sought to evaluate the usefulness of coronary sinus filling time (CSFT) to assess coronary microcirculation in this group of patients.
METHODS: We compared the CSFT of patients having definite angina or atypical angina with positive treadmill electrocardiography test (angina group), with that of patients undergoing coronary angiogram (CAG) prior to balloon mitral valvuloplasty (control group). During CAG, coronary sinus was visualized in appropriate views and CSFT in seconds was derived from frame count. Thrombolysis In Myocardial Infarction (TIMI) flow grade, corrected TIMI (cTIMI) frame count, TIMI Myocardial Perfusion grade (TMP) were assessed.
RESULTS: There were 41 patients in angina group and 16 in control group. Among the angina group 68.8% were females as against 81.8% in the control group. 87.8% (n = 36) had typical angina. Mean CSFT was 4.25 ± 0.72 s and 3.46 ± 0.99 s in the angina group and control group respectively (p = 0.001). No significant differences were found between the groups with respect to TMP (p = 0.68) & cTIMI frame count (p = 0.22).
CONCLUSION: CSFT is a simple method to assess the transit time through coronary microcirculation. CSFT was significantly delayed in patients with angina and normal coronaries. TMP and cTIMI frame count were not significantly different between groups.

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Saturday, February 22, 2014

Initial human experience with Rubidium-82 renal PET/CT imaging.

Initial human experience with Rubidium-82 renal PET/CT imaging.
J Med Imaging Radiat Oncol. 2014 Feb;58(1):25-31
Authors: Tahari AK, Bravo PE, Rahmim A, Bengel FM, Szabo Z

INTRODUCTION: Preclinical data have shown that Rubidium-82 chloride ((82) Rb) is a radiotracer with high first pass extraction and slow washout in the kidneys. The goal of this study was to investigate the feasibility of human kidney imaging with (82) Rb positron emission tomography (PET) and obtain quantitative data of its uptake non-invasively.
METHODS: Eight healthy volunteers underwent dynamic PET/CT imaging with (82) Rb. A preprogrammed pump was used to insure reproducible injections. Tissue time activity curves were generated from the renal cortex. An input function was derived from the left ventricular blood pool (LVBP), the descending thoracic aorta and the abdominal aorta. Renal blood flow was estimated by applying a two-compartment kinetic model. Results obtained with different input functions were compared.
RESULTS: Radiotracer accumulation was rapid and reached a plateau within 15-30 s after the bolus entered the kidneys. The derived K1 and k2 parameters were reproducible using input functions obtained from diverse vascular locations. K1 averaged 1.98 ± 0.14 mL/min/g. The average k2 was 0.35 ± 0.11/min. Correlation between K1 values obtained from the LVBP from different bed positions when the kidneys and abdominal aorta were in the same field of view was excellent (R = 0.95).
CONCLUSIONS: Non-invasive quantitative human kidney imaging with (82) Rb PET is feasible. Advantages of renal PET with (82) Rb include excellent image quality with high image resolution and contrast. (82) Rb has potential as a clinical renal imaging agent in humans.

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Patient- and clinician-reported satisfaction with pharmacological stress agents for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).

Patient- and clinician-reported satisfaction with pharmacological stress agents for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).
J Med Econ. 2013;16(6):828-34
Authors: Hudgens S, Breeze J, Spalding J

OBJECTIVE: The objective of this study was to compare clinician and patient measures of satisfaction with two pharmacological stress agents (PSA), regadenoson and dipyridamole, used in Single Photon Emission Computed Tomography (SPECT) Myocardial Perfusion Imaging (MPI).
METHODS: This observational study included patients who had undergone SPECT MPI with regadenoson or dipyridamole, as well as the clinician/clinical technologist who performed the test. Mean scores for individual item and domain scores of the main outcome measures were computed as well as the effect sizes (ES) of the mean difference in scores between treatment groups. Statistical significance of the mean item and domain score differences were assessed via Mann-Whitney tests. Main outcome measures: Two self-report questionnaires which had beeb previously developed and validated: Patient Satisfaction/Preference Questionnaire (PSPQ) and Clinician Satisfaction/Preference Questionnaire (CSPQ).
RESULTS: A total of 87 patients (68 received regadenoson, 19 received dipyridamole) and nine clinicians/clinical technologists took part in the study. Patients had a mean age of 66.8 ± 12.2 years, and 56.3% were male. Compared to dipyridamole, use of regadenoson was associated with greater clinician satisfaction on all items and domains of the CSPQ (p < 0.001 for all comparisons). Among patients, regadenoson was associated with less bother and greater satisfaction than dipyridamole for all items on the PSPQ. These patients reported less stinging at the injection site (ES = -0.66) and less nervousness during injection (ES = -0.60). The PSPQ found that regadenoson patients were more satisfied with their PSA than dipyridamole patients in all areas.
LIMITATIONS: This study utilized a relatively small sample size of dipyridamole patients and lacked an adenosine group. A broader sampling of professionals would also help demonstrate generalizability.
CONCLUSION: Both patients and clinicians reported higher satisfaction with regadenoson compared to dipyridamole for SPECT-MPI. Clinicians were particularly satisfied with the preparation and administration aspects of the drug, while patients rated it highly on convenience and reduced incidence of side-effects.

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Successful transcatheter closure of coronary artery fistula in a child with single coronary artery: a heavy load and a long road.

Successful transcatheter closure of coronary artery fistula in a child with single coronary artery: a heavy load and a long road.
Catheter Cardiovasc Interv. 2013 Jul 1;82(1):150-4
Authors: Phasalkar M, Thakkar B, Poptani V

Single coronary artery is an uncommon variation of the coronary circulation. After transposition of great arteries, coronary artery fistulas are the most common associated cardiac anomalies in these patients. Transcatheter closure of coronary artery fistula (CAF) involving single coronary artery is a challenging intervention. In the absence of contralateral coronary artery, a complex anatomy of the CAF and a large myocardial perfusion territory of the dominant circulation pose an additional risk during interventional procedure. We report our experience of a successful transcatheter closure of a coronary artery fistula in a patient with single coronary artery.

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'Warm-up Angina': harnessing the benefits of exercise and myocardial ischaemia.

'Warm-up Angina': harnessing the benefits of exercise and myocardial ischaemia.
Heart. 2014 Jan;100(2):106-14
Authors: Williams RP, Manou-Stathopoulou V, Redwood SR, Marber MS

The phenomenon of warm-up angina was first noted over 200 years ago. It describes the curious observation whereby exercise-induced ischaemia on second effort is significantly reduced or even abolished if separated from first effort by a brief rest period. However, the precise mechanism via which this cardio-protection occurs remains uncertain. Three possible explanations for reduced myocardial ischaemia on second effort include: first, an improvement in myocardial perfusion; second, increased myocardial resistance to ischaemia similar to ischaemic preconditioning; and third, reduced cardiac work through better ventricular-vascular coupling. Obtaining accurate coronary physiological measurements in the catheter laboratory throughout exercise demands a complex research protocol. In the 1980s, studies into warm-up angina relied on great cardiac vein thermo-dilution to estimate coronary blood flow. This technique has subsequently been shown to be inaccurate. However exercise physiology in the catheter laboratory has recently been resurrected with the advent of coronary artery wires that allow continuous measurement of distal coronary artery pressure and blood flow velocity. This review summarizes the intriguing historical background to warm-up angina, and provides a concise critique of the important studies investigating mechanisms behind this captivating cardio-protective phenomenon.

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Wednesday, February 19, 2014

Validation of an automated method to quantify stress-induced ischemia and infarction in rest-stress myocardial perfusion SPECT.

Validation of an automated method to quantify stress-induced ischemia and infarction in rest-stress myocardial perfusion SPECT.
J Nucl Cardiol. 2014 Feb 15;
Authors: Fransson H, Ljungberg M, Carlsson M, Engblom H, Arheden H, Heiberg E

BACKGROUND: Myocardial perfusion SPECT (MPS) is one of the frequently used methods for quantification of perfusion defects in patients with known or suspected coronary artery disease. This article describes open access software for automated quantification in MPS of stress-induced ischemia and infarction and provides phantom and in vivo validation.
METHODS AND RESULTS: A total of 492 patients with known or suspected coronary artery disease underwent both stress and rest MPS. The proposed perfusion analysis algorithm (Segment) was trained in 140 patients and validated in the remaining 352 patients using visual scoring in MPS by an expert reader as reference standard. Furthermore, validation was performed with simulated perfusion defects in an anthropomorphic computer model. Total perfusion deficit (TPD, range 0-100), including both extent and severity of the perfusion defect, was used as the global measurement of the perfusion defects. Mean bias ± SD between TPD by Segment and the simulated TPD was 3.6 ± 3.8 (R (2) = 0.92). Mean bias ± SD between TPD by Segment and the visual scoring in the patients was 1.2 ± 2.9 (R (2 )= 0.64) for stress-induced ischemia and -0.3 ± 3.1 (R (2) = 0.86) for infarction.
CONCLUSION: The proposed algorithm can detect and quantify perfusion defects in MPS with good agreement to expert readers and to simulated values in a computer phantom.

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CT-based attenuation correction in Tl-201 myocardial perfusion scintigraphy is less effective than non-corrected SPECT for risk stratification.

CT-based attenuation correction in Tl-201 myocardial perfusion scintigraphy is less effective than non-corrected SPECT for risk stratification.
J Nucl Cardiol. 2014 Feb 15;
Authors: Savvopoulos CA, Spyridonidis T, Papandrianos N, Vassilakos PJ, Alexopoulos D, Apostolopoulos DJ

BACKGROUND: Previous studies advocate the use of attenuation correction in myocardial perfusion scintigraphy (MPS) for patient risk stratification.
METHODS: Six-hundred and thirty-seven unselected patients underwent Tl-201 MPS by a hybrid SPECT/CT system. Attenuation-corrected (AC) and non-corrected (NAC) images were interpreted blindly and summed stress scores (SSS) were calculated. Study endpoints were all-cause mortality and the composites of death/non-fatal acute myocardial infarction (AMI) and death/AMI/late revascularization.
RESULTS: During a follow-up of 42.3 ± 12.8 months 24 deaths, 13 AMIs and 28 revascularizations were recorded. SSS groups formed according to event rate distribution across SSS values were: 0-4, 5-13, >13 for NAC and 0-2, 3-9, >9 for AC. Kaplan-Meier functions were statistically significant between NAC SSS groups for all study endpoints. AC discriminated only between SSS 0-2 and >9 for death/AMI and between 0-2 and 3-9 for death/AMI/revascularization. In the univariate Cox regression abnormal NAC (SSS > 4) was accompanied with much higher hazards ratios than abnormal AC (SSS > 2). In the multivariate model abnormal AC yielded no significance for either endpoint whereas abnormal NAC proved independent from other covariates for the composite endpoints.
CONCLUSION: Our results challenge the effectiveness of CT-based AC for risk stratification of patients referred for MPS.

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The effects of dobutamine stress on cardiac mechanical synchrony determined by phase analysis of gated SPECT myocardial perfusion imaging in a canine model.

The effects of dobutamine stress on cardiac mechanical synchrony determined by phase analysis of gated SPECT myocardial perfusion imaging in a canine model.
J Nucl Cardiol. 2014 Jan 9;
Authors: Salimian S, Thibault B, Finnerty V, Grégoire J, Harel F

BACKGROUND: Precise identification of left ventricular (LV) systolic mechanical dyssynchrony may be useful in optimizing the response to cardiac resynchronization therapy in heart failure (HF) patients. However, LV dyssynchrony is mostly measured at rest; patients often suffer from the HF symptoms during exercise.
OBJECTIVES: Our objective was to examine the impacts of stress on LV synchronism with phase analysis of gated SPECT myocardial perfusion imaging (GMPS) within a normal animal cohort.
METHODS: Stress was induced with different levels of dobutamine infusion in six healthy canine subjects. Hemodynamic properties were assessed by LV pressure measurements. Also, LV mechanical synchronism (coordination of LV septal and lateral wall at the time of contraction) was determined by phase analysis of GMPS using commercially available QGS software and in-house MHI4MPI software, with the thickening- and displacement-based method. Synchrony indexes in MHI4MPI included the septal-to-lateral delay and homogeneity index, derived from each of the two methods. Also, bandwidth, SD, and entropy (synchrony indexes) of the QGS software were assessed.
RESULTS: LVEF increased from 36.7% ± 8.7% at rest to 53.67% ± 12.34% at 20 μg·kg(-1)·minute(-1) (P < .001). Also, cardiac output increased from 3.67 ± 1.0 L·minute(-1) at rest to 8.4 ± 2.6 L·minute(-1) at 10 μg·kg(-1)·minute(-1) (P < .001). The same trend was observed for dP/dt max which increased from 1,247 ± 382.7 at rest to 5,062 ± 1,800 mm Hg·s(-1) at 10 μg·kg(-1)·minute(-1) (P < .01). Entropy decreased from 55.2% ± 8% at baseline to 43.5% ± 8.5% at 5 and 43.0% ± 3.7% at 10 μg·kg(-1)·minute(-1) dobutamine (P < .01). Thickening homogeneity index showed a difference from 91.7% ± 5.53% at rest to 98.2% ± 0.75% at 20 μg·kg(-1)·minute(-1) (P < .05).
CONCLUSIONS: Dobutamine stimulation could amplify the ventricular synchronism, and the thickening-based approach is more accurate than wall displacement for assessment of mechanical dyssynchrony in GMPS.

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Tuesday, February 18, 2014

Use of myocardial perfusion imaging and estimation of associated radiation doses in Germany from 2005 to 2012.

Use of myocardial perfusion imaging and estimation of associated radiation doses in Germany from 2005 to 2012.
Eur J Nucl Med Mol Imaging. 2014 Feb 12;
Authors: Lindner O, Bengel FM, Hacker M, Schäfer W, Burchert W, Working Group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine

PURPOSE: For several years the Working Group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine has been performing a regular survey to obtain information on technique, utilization and development of myocardial perfusion scintigraphy (MPS). Currently, data of six surveys from 2005 to 2012 are available. The aim of this paper is to deliver a general and comprehensive overview of all surveys documenting the course of patient doses over time and the development of the method.
METHODS: A one-page questionnaire with number of MPS patients, number of stress and rest MPS, referral structure and several technical issues was sent to all centres performing MPS in Germany and evaluated. With the data on protocol utilization, effective MPS patient doses were estimated.
RESULTS: MPS per million population (pmp) varied between 2,380 and 2,770. In 2012, MPS pmp showed a slight increase for the first time. From 2005 to 2009 the angiography to MPS ratio increased from 3.4 to 4.4, and the revascularization to MPS ratio decreased from 0.66 to 0.53. In 2012, both indices demonstrated an opposite trend for the first time (4.1 and 0.55). A total of 108 centres participated in all surveys. They showed an increase in MPS patients of 4.0 % over the reporting period. In 2012, more than 50 % of the centres experienced no change or an increase in MPS numbers. The leading single competitor was MRI, followed by angiography and stress echocardiography. (201)Tl studies have decreased since 2005 from 20 to 5 %. (99m)Tc MPS studies showed a mild increase in 2-day protocols. In 2012, the average effective dose per patient was estimated at 7.4 mSv. Due to the decreasing use of (201)Tl, a mild decline over the observation period can be documented. Dynamic exercise stress was the most common stress test and adenosine the leading pharmacological stress agent, with a growing percentage. In 2012, the regadenoson percentage was 9 %. Gated single photon emission computed tomography (SPECT) noted an increasing acceptance with >70 % in 2012. The segmental scoring of perfusion studies had a low acceptance. Ambulatory care cardiologists represented the major referral group.
CONCLUSION: Germany has a moderate to moderate-high MPS utilization rate. Nevertheless, coronary artery disease (CAD) diagnosis and disease management are dominated by angiography. The survey data reveal a positive trend in MPS and a decrease in average patient dose reflecting good practice with guideline adherence, the implementation of technical improvements and success in training.

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Sunday, February 16, 2014

Angiographic outcomes in the PLATO Trial (Platelet Inhibition and Patient Outcomes).

Angiographic outcomes in the PLATO Trial (Platelet Inhibition and Patient Outcomes).
JACC Cardiovasc Interv. 2013 Jul;6(7):671-83
Authors: Kunadian V, James SK, Wojdyla DM, Zorkun C, Wu J, Storey RF, Steg PG, Katus H, Emanuelsson H, Horrow J, Maya J, Wallentin L, Harrington RA, Gibson CM

OBJECTIVES: The PLATO (Platelet Inhibition and Patient Outcomes) angiographic substudy sought to compare the efficacy of ticagrelor versus clopidogrel with respect to angiographic outcomes before and after PCI in the setting of acute coronary syndrome.
BACKGROUND: Greater platelet inhibition has been associated with improved angiographic outcomes before and after percutaneous coronary intervention (PCI). Therefore, it was hypothesized that treatment with ticagrelor, which achieves more rapid, higher, and more consistent platelet inhibition, would be associated with improved angiographic outcomes when compared with those of clopidogrel treatment.
METHODS: The angiographic cohort consists of 2,616 patients drawn from the 18,624-patient PLATO trial. Clopidogrel naïve or pre-treated patients were randomized to 180 mg of ticagrelor or 300 mg of clopidogrel (75 mg for clopidogrel pre-treated patients). PCI patients were administered, as per treatment group: 1) an additional 90 mg of ticagrelor if >24 h following the initial loading dose; or 2) an optional further 300 mg of clopidogrel or placebo (total 600 mg) prior to PCI. The substudy primary endpoint was the incidence of post-PCI TIMI (Thrombolysis In Myocardial Infarction) myocardial perfusion grade 3 (TMPG 3) among patients who received a study drug prior to PCI.
RESULTS: In total, 21.3% of patients were pretreated with clopidogrel prior to randomization. There was a short time interval between randomization and PCI (median: 0.68 [interquartile range (IQR): 0.30 to 2.21] h) among all patients. Post-PCI TMPG 3 was similar between the ticagrelor and clopidogrel groups (47.1% vs. 46.9%; p = 0.96). Likewise, the following pre-PCI outcomes were similar in the ticagrelor and clopidogrel groups, respectively: TMPG 3 (30.5% vs. 31.2%), TIMI flow grade 3 (37.1% vs. 39.3%), corrected TIMI frame count (median: 100 vs. 71 frames), TIMI thrombus grade 0 (24.1% vs. 27.6%), minimum lumen diameter (median: 0.3 [IQR: 0.0 to 0.6] vs. 0.3 [IQR: 0.0 to 0.6] mm) and percentage of diameter stenosis (median: 89 [IQR: 78 to 100] vs. 89 [IQR: 77 to 100]).
CONCLUSIONS: Neither coronary flow nor myocardial perfusion, evaluated on coronary angiograms performed before or following PCI procedures within a few hours after the start of oral antiplatelet treatment in the setting of acute coronary syndromes, demonstrated a difference with ticagrelor versus clopidogrel. (A Comparison of Ticagrelor [AZD6140] and Clopidogrel in Patients With Acute Coronary Syndrome [PLATO]; NCT00391872).

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Friday, February 14, 2014

Is the diagnostic yield of myocardial stress perfusion MRI impaired by three-vessel coronary artery disease?

Is the diagnostic yield of myocardial stress perfusion MRI impaired by three-vessel coronary artery disease?

Acta Radiol. 2014 Feb 12;

Authors: Klumpp B, Miller S, Seeger A, May A, Gawaz M, Claussen C, Kramer U

BACKGROUND: Three-vessel coronary artery disease (CAD) comes along with globally reduced myocardial perfusion potentially restricting the demarcation of regional hypoperfusion in stress perfusion cardiac magnetic resonance imaging (MRI).
PURPOSE: To evaluate whether stress perfusion cardiac MRI is capable of detecting myocardial hypoperfusion in patients with 3-vessel CAD reliably.
MATERIAL AND METHODS: Two hundred and five patients with symptoms of CAD were included. The examination protocol comprised imaging of myocardial perfusion at stress (0.14 mg/kg/min adenosine for 4 min) using a 2D saturation recovery gradient echo sequence after administration of gadobutrol (0.1 mmol/kg body weight). Perfusion sequences were assessed qualitatively by two experienced observers. Coronary angiography served as standard of reference.
RESULTS: Sensitivity and specificity for hemodynamically relevant stenoses in patients with 0-, 1-, 2-, 3-vessel coronary artery disease were 100%/91%, 91%/73%, 90%/71%, 92%/64%; positive/negative predictive value, 67%/100%, 91%/73%, 83%/81%, 93%/58%; diagnostic accuracy, 93%/87%/83%/87%, respectively. The negative predictive value in patients with 3-vessel CAD was lower than in patients with 0- and 2-vessel CAD and the specificity lower than in patients with no CAD whereas the positive predictive value was higher than in patients with no CAD. The other proportions did not differ significantly between the groups.
CONCLUSION: The diagnostic value of stress perfusion cardiac MRI in patients with 3-vessel CAD is comparable to results in patients with 1- or 2-vessel CAD. In the rare event that stress perfusion images do not depict regional hypoperfusion in patients with severe 3-vessel CAD, myocardial ischemia could be identified by reduced semi-quantitative perfusion parameters.


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