BIPHASIC RESPONSE TO DOBUTAMINE PREDICTS IMPROVEMENT OF GLOBAL LEFT-VENTRICULAR FUNCTION AFTER SURGICAL REVASCULARIZATION IN PATIENTS WITH STABLE CORONARY-ARTERY DISEASE - IMPLICATIONS OF TIME-COURSE OF RECOVERY ON DIAGNOSTIC-ACCURACY

Objectives. This study sought to evaluate the time course of improveme nt of left ventricular (LV) dysfunction in stable patients and its imp lications on the accuracy of dobutamine echocardiography for predictin g improvement after surgical revascularization. Background. Little is known about the optimal timing for evaluation of postrevascularization recovery of the contractile function of viable myocardium. Methods. S ixty-one patients with chronic ischemic LV dysfunction scheduled for e lective surgical revascularization were prospectively selected. They u nderwent dobutamine echocardiography (5 to 40 mu g/kg body weight per min) and radionuclide ventriculography both preoperatively and at 3 mo nth follow-up. At 14 months, another evaluation of LV function was obt ained. To analyze echocardiograms, a 16-segment model and a five-point scoring system were used. Dyssynergic segments were considered likely to recover in the presence of a biphasic contractile response to dobu tamine. Improvement of global function was defined as a greater than o r equal to 5% increase in LV ejection fraction (LVEF). Results. Of the 61 patients, LVEF improved in 12 at 3 months and in 19 at late follow -up (from 32 +/- 8% to 42 +/- 9%, p < 0.0001). The frequency and time course of improvement of LVEF were similar in patients with mild and s evere LV dysfunction. A biphasic response, identified in 186 of the 53 7 dyssynergic segments, was predictive of recovery in 63% at 3 months and in 75% at late follow-up. The positive predictive value was best i n the most severe dyssynergic segments (90% vs. 67%). Other responses were highly predictive for nonrecovery (92%). The sensitivity and spec ificity for improvement of global function on a patient basis (greater than or equal to 4 biphasic segments) were 89% and 81%, respectively, at late follow-up. Conclusions. Serial postoperative follow-up studie s demonstrate incomplete recovery of contractile function at 3 months. The diagnostic accuracy of dobutamine echocardiography for predicting recovery is dependent on three factors: the combining of low and high dobutamine dosages, the severity of regional dyssynergy and the timin g of evaluation. (C)1998 by the American College of Cardiology.