Effects of thrombolytic therapy on evolution of left ventricular function in acute myocardial infarction

Use of thrombolytic therapy in the early hours of acute myocardial infarction (AMI) has gained widespread acceptance. One potential benefit of early reperfusion could be improved left ventricular (LV) function. Experimental animal studies have demonstrated that duration of coronary occlusion determines ultimate infarct size and have also raised the issue of reperfusion injury. The evolution of LV function after AMI in man where there is no attempt at early reperfusion is discussed. Studies of LV function following thrombolytic therapy in man have illustrated the following points. Time to successful reperfusion appears to be a critical determinant for potential for LV functional recovery. If reperfusion is achieved within 2.5 hours after onset of symptoms, consistent recovery of function within the infarct zone appears to be possible. With reperfusion from 2.5 to six hours after onset of symptoms, there is no predictable, substantial improvement in either global or regional LV function. Within the framework of this general conclusion, there are three potential exceptions: Successful reperfusion up to six hours after onset of symptoms may prevent infarct expansion. Patients with subtotal occlusion of the infarct vessel prior to therapy in this time period may have more potential for recovery of LV function than those with initial total occlusion. A tight residual stenosis following thrombolytic therapy may mask potential for functional recovery in the infarct zone. Earlier diagnosis and treatment of AMI is one obvious solution for the overall lack of beneficial results on evolution of LV function seen in most studies to date.(ABSTRACT TRUNCATED AT 250 WORDS)