Effects of antianginal therapy with a calcium antagonist and nitrates on dobutamine-atropine stress echocardiography. Comparison with exercise electrocardiography

Abstract

Background. Anti-ischaemic therapy with nitrates and/or calcium channel blockers profoundly affects the results of pharmacological stress echocardiography with coronary vasodilators but the influence on catecholamine stress testing remains unsettled. Aims. The present study aimed to assess the effects of non-beta-blocker antianginal therapy on dobutamine (up to 40 μg.kg-1. min-1)-atropine (up to 1 mg) stress echocardiography and to evaluate whether drug-induced changes in the dobutamine-atropine stress echocardiography response may predict variations in exercise tolerance. Methods. Twenty six patients with angiographically assessed coronary artery disease (seven patients with single-, 10 with double-, and nine with triple-vessel disease) performed a dobutamine-atropine stress echocardiography and an exercise electrocardiography test in random order both off and on antianginal drugs (nitrates and calcium antagonists). In dobutamine-atropine stress echocardiography, we evaluated: dobutamine time (i.e. the time from initiation of the dobutamine infusion to obvious dyssynergy), wall motion score index (in a 16-segment model of the left ventricle, each segment ranging from 1 = normal, to 4 =.dyskinetic), and rate-pressure product at peak stress. Results. Dobutamine-atropine stress echocardiography positivity occurred in 26 out of 26 patients off and in 23 patients on therapy (100 vs 88%, P = ns). Atropine coadministration was needed to evoke echo positivity in no patient off and in five out of 26 on therapy (0 vs 19%, P < 0.01). The achieved rate-pressure product during dobutamine-atropine stress echocardiography was comparable on and off therapy (17 ± 4 vs 19 ± 5 x 103mmHg x heart rate.min-1, P = ns). Therapy induced an increase in dobutamine time (on = 16 ± 3 vs off = 13 ± 3 min, P < 0.01) and a decrease in peak wall motion score index (on = 13 ± 0.2 vs off = 1.5 ± 0.3, P < 0.01). The therapy induced changes in exercise time during the exercise electrocardiography test were not significantly correlated to dobutamine-atropine stress echocardiography variations in either dobutamine time (r = 0.07, P = ns), or peak ratepressure product (r = 0.24, P = ns), or peak wall motion score index (r = 0.02, P = ns). Conclusions. (1) non-beta-blocker antianginal therapy only modestly reduces dobutamine-atropine stress echocardiography sensitivity, although atropine coadministration is more often requuired to reach stress echo positivity under therapy; (2) therapy reduces the severity of dobutamine-atropine stress echocardiography ischaemia stratified in the time and space domain, but these changes are only poorly correlated to variations in exercise tolerance.