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