DOBUTAMINE VERSUS DIPYRIDAMOLE-MAGNETIC R ESONANCE IMAGING - SAFETY AND SENSITIVITY FOR THE DIAGNOSIS OF CORONARY-ARTERY STENOSES

Safety and sensitivity of gradient-echo magnetic resonance imaging (MR I) for the identification of significant coronary artery stenoses usin g pharmacologic stress testing was assessed in 61 patients with greate r-than-or-equal-to 70 % stenosis of a major coronary artery and a norm al left ventricle. After MRI at rest 28 patients underwent dobutamine- MRI during steady-state dobutamine infusion (5, 10, 15 and 20 mug/kg/m in) and 33 patients had dipyridamole-MRI after high-dose dipyridamole infusion (0.75 mg/kg over 10 min). All patients additionally performed standard ECG exercise stress testing (EST). Segmental wall motion ana lysis was performed in basal and midventricular short axis tomograms b y two observers. A segment was graded pathologic if transient dobutami ne or dipyridamole induced wall motion abnormalities could be detected . For comparison to coronary angiography findings, each segment was as signed to one of the coronary artery perfusion territories. There were no serious side-effects during dobutamine and dipyridamole infusion l eading to termination of the study protocol. Peak double product durin g dobutamine infusion was significantly higher (p < 0.001) than after dipyridamole infusion (18.493 +/- 4.311 versus 12.799 +/- 2.694 mm Hg/ min). Overall sensitivity of dobutamine and dipyridamole-MRI for coron ary artery disease (CAD) was 85 % and 84 %. Regional asynergy by dobut amine and dipyridamole-MRI was observed in 73 % versus 79 % patients w ith single- and 100 % versus 92 % with multi-vessel disease. Individua l coronary artery stenoses were correctly identified by segmental wall motion abnormalities in 87 % versus 81 % for left anterior descending , 62 % versus 86 % for left circumflex and 78 % versus 92 % for right coronary artery stenoses. In conclusion, dobutamine and dipyridamole-M RI are well tolerated and safe non-exercise dependent tests for detect ion and localization of hemodynamically significant coronary artery st enoses with a similar diagnostic accuracy but with a better control of stress intensity and duration provided by dobutamine.