The influence of clopidogrel on ischemia diagnosed by myocardial perfusion stress testing.

ABSTRACT

BACKGROUND: Clopidogrel is a platelet adenosine receptor antagonist which can influence coronary vascular tone and thus can potentially interfere with myocardial perfusion imaging. We investigated whether clopidogrel can hamper the diagnosis of ischemia in patients undergoing myocardial perfusion testing. METHODS: Data from a database of 6349 myocardial perfusion stress tests were analyzed. Using a propensity analysis, patients who were taking clopidogrel were compared with patients not taking clopidogrel for the presence of reversible perfusion defects on myocardial single-photon emission computed tomography scans. RESULTS: Of the 6349 tests, the stress technique was adenosine in 2713 patients and exercise in 3636. At the time of the stress test, 277 (4.3%) of the patients were taking clopidogrel. The odds ratio (OR) for patients taking clopidogrel to have a reversible perfusion defect was 2.75 (95% confidence interval [CI] 2.09-3.62; P < .01). After adjusting for the propensity to take clopidogrel, the OR was 1.06 (CI 0.76-1.49; P = .73) for patients undergoing adenosine stress tests and 1.60 (CI 0.85-3.00; P = .14) for patients undergoing exercise stress tests. CONCLUSIONS: We found no evidence that the use of clopidogrel decreases the likelihood of ischemia on adenosine or exercise stress myocardial perfusion scans.