Seventy-eight consecutive patients (mean 63 +/- 10 years, 79.5% men) with a history of myocardial infarction and indication of coronary artery bypass grafting (CABG) were studied with low dose dobutamine stress echocardiography (DSE) before (DSE 1) and at 3-month follow-up (DSE 2) to evaluate its clinical utility in the detection of viable myocardium. We determined the expected utilities of global patients (P; n = 67) and coronary territories (T; n = 126) with the classic strategy: DSE 1 and results of a rest follow-up echocardiogram (REST 2) and applying them to a complementary strategy that submitted false positives (Fp) and false negatives (Fn) results to DSE 2. Assigned utilities in each node of the decision tree were maximal (1.0), submaximal ( 0.75), and intermedium (0.50) using the folding method as a mathematical model.
Results: Global P and T expected utilities when performing DSE 1 were 0.84 and 0.89, respectively for positive viability; 0.85 and 0.82, respectively; and for negative viability 0.83 and 0.82, respectively. The expected utilities with the decision of performing a DSE 2 to Fp were 0.74 and 0.76, respectively (viability was detected in 66% of P and in 58% of T) and 0.47 and 0.45, respectively, as applied to Fn.
Conclusions: Low dose DSE results in high clinical utility by finding viable or scar myocardium before CABG as well as when discordant results are found in follow-up, particularly with Fp.