Comparison and combination of dipyridamole and dobutamine during echocardiography with thallium scintigraphy to improve viability detection

The aim of this study was to investigate the relation between radioisotopic and echocardiographic markers of myocardial viability and their correlatio n with functional recovery after coronary revascularization. Myocardial via bility can be detected by techniques exploring various aspects of cell phys iology: thallium-201 scintigraphy and dobutamine and dipyridamole echocardi ography focus on cell membrane integrity, beta-l and adrenoceptor, and A2-a denosine receptor-mediated inotropic response, respectively. Fifty-seven pa tients (mean age 60 +/- 8 years) with previous myocardial infarction (>3 mo nths), angiographically assessed coronary artery disease, and resting regio nal dysfunction underwent rest-redistribution 201-thallium scintigraphy and low-dose pharmacologic stress echo with dobutamine (up to 10 mu g/kg/min), very low dose regimen of dipyridamole (0.28 mg/kg over 4 minutes), and com bined dipyridamole-dobutamine. Criteria for viability in a 13-segment model for both techniques were percent peak activity in redistribution images >5 5% for thallium-201 and a decrease in wall motion score >1 grade (1 [normal ] to 4 [dyskinetic]) for stress echo. Thirty patients underwent coronary re vascularization (bypass surgery in 8, angioplasty in 22) and were followed up at 4 weeks from intervention with a resting echocardiogram. The rate of agreement between thallium-201 and stress echo was 63% for dipyridamole, 66 % for dobutamine, and 74% for combined dipyridamole-dobutamine (p <0.05 vs dipyridamole and dobutamine). In the 30 patients who underwent revasculariz ation, a regional resting dyssynergy was observed in 225 segments, assuming that postrevascularization functional recovery (which occurred in 126 segm ents) was the gold standard; combined dipyridamole-dobutamine showed a high er sensitivity (90% confidence interval [CI] 85% to 95%) than thallium-201, dobutamine, or dipyridamole (87%, CI 81% to 92%; 82%, CI 76% to 89%; and 8 2%, CI 76% to 89%, respectively). Specificity was lower for viability recog nition with thallium-201 (61%, CI 51% to 71%) than with dobutamine (93%, CI 88% to 98%), dipyridamole (95%, CI 91% to 99%), and combined dipyridamole- dobutamine (92%; CI 87% to 97%). Combined adrenergic and adenosinergic stim ulation recruits an inotropic reserve in a significant proportion of segmen ts with preserved thallium uptake that were nonresponders after either dipy ridamole or dobutamine. When functional recovery after successful revascula rization is considered as the postoperative gold standard, thallium has a h igher sensitivity than dipyridamole or dobutamine; this sensitivity gap is filled with combined dipyridamole-dobutamine. The specificity of all forms of pharmacologic stress echo is better than thallium-201. (C)1999 by Excerp ta Medica, Inc.