PROGNOSTIC VALUE OF MYOCARDIAL VIABILITY IN MEDICALLY TREATED PATIENTS WITH GLOBAL LEFT-VENTRICULAR DYSFUNCTION EARLY AFTER AN ACUTE UNCOMPLICATED MYOCARDIAL-INFARCTION - A DOBUTAMINE STRESS ECHOCARDIOGRAPHIC STUDY

Background-Residual viable myocardium identified by dobutamine stress after myocardial infarction may act as an unstable substrate for furth er events such as subsequent angina and reinfarction. However, in pati ents with severe global left ventricular dysfunction, viability might be protective rather than detrimental. The aim of this study was to as sess the impact on survival of echocardiographically detected viabilit y in medically treated patients with global left ventricular dysfuncti on evaluated after acute uncomplicated myocardial infarction. Methods and Results-The data bank of the large-scale, prospective, multicenter , observational Echo Dobutamine International Cooperative (EDIC) study was interrogated to select 314 medically treated patients (271 men; a ge, 58+/-9 years) who underwent low-dose (less than or equal to 10 mu g . kg(-1) . min(-1)) dobutamine for the detection of myocardial viabi lity and high-dose dobutamine for the detection of myocardial ischemia (less than or equal to 40 mu g . kg(-1) . min(-1) with atropine less than or equal to 1 mg) performed 12+/-6 days after an acute uncomplica ted myocardial infarction and showing a moderate to severe resting lef t ventricular dysfunction (wall motion score index [WMSI] >1.6). Patie nts were followed up for 9+/-7 months. Low-dose dobutamine stress echo cardiography identified myocardial viability in 130 patients (52%). Do butamine-atropine stress echocardiography was positive for ischemia in 148 patients (47%) and negative in 166 patients (53%). During the fol low-up, there were 12 cardiac deaths (3.8% of the total population). W ith the use of Cox proportional hazards model, delta low-dose WMSI (th e variation between rest WMSI and low-dose WMSI) was shown to exert a protective effect by reducing cardiac death by 0.8 for each decrease i n WMSI at low-dose dobutamine (coefficient, -0.2; hazard ratio, 0.8; P <0.03); WMSI at peak stress was the best predictor of cardiac death in this set of patients (hazard ratio, 14.9; P<0.0018). Conclusions-In m edically treated patients with seven global left ventricular dysfuncti on early after acute uncomplicated myocardial infarction, the presence of myocardial viability identified as inotropic reserve after low-dos e dobutamine is associated with a higher probability of survival. The higher the number of segments showing improvement of function, the bet ter the impact is of myocardial viability on survival. The presence of inducible ischemia in this set of patients is the best predictor of c ardiac death.