Effect of antianginal medication on resting myocardial perfusion and pharmacologically induced hyperemia

Background. Patients scheduled for myocardial perfusion imaging are often taking several antianginal drugs. There is presently no consensus concerning a regimen of discontinuation before either rest or pharmacologic stress myocardial perfusion imaging. Whether antianginal treatment affects diagnostic sensitivity and specificity is not well documented. Methods and Results. The effect of the three most commonly used antianginal drugs (nitroglycerin, 400 micro g [NTG]; metoprolol, 50 mg [MET]; and amlodipine, 5 mg [AML]) on myocardial perfusion was tested in 49 patients (age, 63 +/- 8 years; 43 men) allocated prospectively to one of the treatments (NTG, n = 25; MET, n = 14; and AML, n = 10). All patients had documented coronary artery disease and were scheduled for elective percutaneous coronary intervention. Patients were studied once on treatment and once off treatment with an interval of 1 to 3 weeks. For NTG, the measurements were performed on the same day with an interval of 1 hour. The MET and AML groups were also studied during dipyridamole-induced hyperemia (0.56 mg. kg(-1). min(-1) for 4 minutes). So that a quantitative value of myocardial perfusion in milliliters per gram per minute could be obtained, myocardial perfusion was quantified with nitrogen 13 ammonia positron emission tomography as an average of the midventricular perfusion in each of the 3 vascular territories. NTG treatment increased the overall resting perfusion (0.75 +/- 0.18 vs 0.86 +/- 0.22, P <.05), whereas resting perfusion was reduced after MET treatment (0.92 +/- 0.14 vs 0.82 +/- 0.17, P <.05). AML treatment did not alter resting perfusion (0.87 +/- 0.22 vs 0.87 +/- 0.23, P = NS). Dipyridamole-induced hyperemia was reduced after treatment with MET (2.02 +/- 0.66 vs l.57 +/- 0.52, P <.001), whereas the hyperemic response was unchanged after treatment with AML (1.54 +/- 0.49 vs 1.86 +/- 0.91, P = NS). Conclusions. Antianginal medication can alter both resting and hyperemic myocardial perfusion and might affect the ability to detect flow-limiting stenosis. NTG increases perfusion, MET reduces perfusion, and AML does not affect perfusion. Larger-scale trials are warranted to establish a consensus for optimal antianginal medication for patients undergoing perfusion imaging.