LOW-DOSE DOBUTAMINE ECHOCARDIOGRAPHIC ASS ESSMENT OF REVERSIBLE CONTRACTILE DYSFUNCTION (MYOCARDIAL STUNNING) AFTER MYOCARDIAL-INFARCTION

Low dose (5 to 10 mu g/min) dobutamine echocardiography was used to pr edict the presence of reversible contractile dysfunction (myocardial s tunning) after myocardial infarction successfully revascularised in th e acute phase of primary angioplasty. The investigation was undertaken in 40 patients, 4 +/- 1 days after inaugural myocardial infarction. T he left ventricle was divided into 16 segments. Viable myocardium was diagnosed when the initial regional wall motion score decreased by at least 2. Resting echocardiography was performed at 2 months to evaluat e the effective recovery of regional wall motion (myocardial viability ). The presence of contractile reserve was documented by dobutamine ec hocardiography in 18 patients (45 %). The sensitivity, specificity and positive and negative predictive values of dobutamine echocardiograph y for the diagnosis of myocardial viability were 82, 83, 78 and 86 % r espectively. The negative predictive value was high in all dysynergic segments (86 %). The positive predictive value of the investigation wa s however higher in hypokinetic than in akinetic segments (73 vs 21 %; p < 0.05). The recovery of regional wall motion during follow-up was statistically related to higher initial left ventricular ejection frac tion (p < 0.04), the presence of angiographically documented collatera l circulation before revascularisation (p = 0.007), the contractile re sponse to dobutamine (p = 0.0001) and was observed more frequently in hypokinetic than in akinetic segments (p < 0.05). These results show t hat low-dose dobutamine echocardiography is a sensitive and specific i nvestigation for predicting irreversible myocardial damage after succe ssful primary angioplasty in acute myocardial infarction. However, eve n in the absence of residual coronary stenosis, the presence of viable myocardium is only identified specifically in hypokinetic segments.