CONTRACTILE RESERVE OF DYSFUNCTIONAL MYOCARDIUM AFTER REVASCULARIZATION - A DOBUTAMINE STRESS ECHOCARDIOGRAPHY STUDY

Objectives. We sought to investigate the effects of revascularization on the contractile reserve of dysfunctional myocardium. Background. Th e improvement in dysfunctional but viable myocardium after revasculari zation is frequently less than expected from the amount of contractile reserve detected on dobutamine stress echocardiography. The fate of t he contractile reserve, when it does not result in an adequate contrac tile recovery, is unknown. Methods. Basal contraction and contractile reserve of infarct zones were assessed by dobutamine stress echocardio graphy in 21 postinfarction male patients before and >3 months after r evascularization (30 infarct zones; mean +/-SD left ventricular ejecti on fraction 35 +/- 8%). An infarct zone wall motion score index (WMSI) was calculated. Results. Before revascularization, contractile reserv e was present in 14 infarct zones (12 patients) and absent in 16 (9 pa tients). After revascularization, ejection fraction increased by 5 +/- 4% (p < 0.01) in patients classified as positive for contractile rese rve and remained unchanged in those classified as negative. New York H eart Association classification improved in 58.3% and 22.2% of patient s, respectively, Basal contraction improved in eight zones with previo us contractile reserve (57.1%) and in one zone without (6.3%) (p < 0.0 1), Contractile reserve was still evident in 13 zones with previous co ntractile reserve (93%; 8 with contractile recovery), and it developed in 6 zones without (38%; none with contractile recovery). WMSI values after revascularization were decreased from values before revasculari zation during low dose dobutamine in zones with and without previous c ontractile reserve (p < 0.01 and < 0.05, respectively). Conclusions. A fter revascularization, contractile reserve is maintained or even incr eases in viable infarct zones that do not recover as expected. It may also develop in some infarct zones judged not to be viable before reva scularization. This increased contractile reserve may play a role in t he functional improvement of patients after revascularization. (C) 199 7 by the American College of Cardiology.