CARDIAC OUTCOMES IN CORONARY PATIENTS WITH SUBMAXIMUM DOBUTAMINE STRESS ECHOCARDIOGRAPHY

This study evaluated the prediction of cardiac events (cardiac death, myocardial infarction, unstable angina, or late myocardial revasculari zation) in patients with submaximum responses to dobutamine stress, de fined by attainment of <85% age-predicted heart rate. Of 1,772 patient s undergoing dobutamine echocardiography over a 2-year period, 425 had a submaximum heart rate response. After exclusion of patients treated with p-adrenoceptor blocking agents, 255 patients formed the study gr oup. In these patients, the test was terminated after administration o f the maximum dose of 40 mu g/kg/min of dobutamine with atropine (end of protocol, n = 186), severe angina, ischemic ST-segment changes, or intolerable side effects (n = 69). Dobutamine-induced changes (ischemi a, viability, or both) were deleted in 46 patients, involving ischemia in 133 segments, viability in 23, and ischemia and viability in 16 se gments. Patients were followed for an interval of 28 +/- 17 months; 5 (1.2%) were lost to follow-up. Of the medically treated patients, card iac events occurred in 73 of 228 (31%), including cardiac-death in 25 (11%), nonfatal myocardial infarction in 11 (4.8%), severe unstable an gina in 35 (15%), and late revascularization in 2 (0.9%). Cardiac even ts occurred in 11 of 30 (36%) with inducible abnormalities, and 62 of 198 without inducible abnormalities (31%, p = NS). Thus, cardiac event rates are high in patients with inadequate chronotropic responses to dobutamine stress, irrespective of whether stress-induced changes are detected. A negative dobutamine echocardiogram at submaximum heart rat e should be considered nondiagnostic. (C) 1997 by Excerpta Medica, Inc .