LAW-DOSE DOBUTAMINE ECHOCARDIOGRAPHY PREDICTS THE EARLY RESPONSE OF DYSFUNCTIONING MYOCARDIAL SEGMENTS TO CORONARY-ARTERY BYPASS-GRAFTING

Dobutamine echocardiography has recently been introduced for use in id entification of viable myocardium in patients with acute myocardial in farction and prediction of the response of dysfunctioning myocardial s egments to coronary angioplasty. The aim of this study was to evaluate whether this test may be used to predict the early response of dysfun ctioning myocardial segments to surgical revascularization. We studied 30 patients with three-vessel disease and chronic, stable angina pect oris during coronary artery bypass grafting (CABG). Patients were moni tored by intraoperative transesophageal echocardiography in the transg astric short-axis view at the papillary muscle lever. The left ventric le was divided into eight segments; and 240 myocardial segments were a nalyzed. Percentage of systolic wall thickening (PSWT) was calculated in each segment at baseline (early after pericardiectomy), before bypa ss during dobutamine infusion (5 mu g/kg/min), and after separation fr om cardiopulmonary bypass. Segments showing PSWT <30% at baseline were considered dysfunctional. Segments showing an increase in PSWT >10% d uring dobutamine infusion were considered responders. Segments showing an increase in PSWT <10% during dobutamine infusion were considered n onresponders. At baseline, 161 (67%) of 240 segments had PSWT <30% (dy sfunctioning segments). During dobutamine, 98 (60%) of these segments increased PSWT >10% (from 11.3% +/- 7.6% to 24.2% +/- 12.0%, p < 0.01; responder segments), and 63 (40%) increased PSWT <10% (from 10.2% +/- 4.9% to 8.3% +/- 5.5%, p value not significant [NS]; nonresponder seg ments). After CABG, responder segments showed a significant increase i n PSWT in comparison with baseline values (from 11.3% +/- 7.6% to 24.4 % +/- 14.0%; p < 0.01). Segments not responding to dobutamine showed n o significant changes in PSWT after CABG (from 10.2% +/- 4.9% to 9.3% +/- 6.6%; p = NS). Seventy-nine normal segments (PSWT 43.9% +/- 12.6%) showed a slight but significant reduction in wall thickening both dur ing dobutamine (PSWT 33.6% +/- 14.0%, p 0.01 vs baseline) and after CA BG (PSWT 32.8% +/- 14.6%; p < 0.01 vs baseline), suggesting that compe nsatory hyperfunction was present at baseline. Estimation of clinical accuracy for transesophageal echocardiography dobutamine-stress test y ielded to 91% sensitivity, 93% specificity, 97% positive predictive va lue, 79% negative predictive value, and 92% overall accuracy. In respo nder segments there was a correlation between PSWT during dobutamine i nfusion and after CABG (r = 0.62).