Infarct size as a determinant of acute and long-term prognosis.

Enzymatic estimates of infarct size based on the analysis of either plasma total or CK-MB activity are substantially larger in patients who succumb to myocardial infarction compared with survivors. Similarly, if patients are stratified according to infarct size calculations, mortality increases as infarct size increases. Enzymatic markers of infarction are closely related to other indicators of prognosis, including infarct type (transmural versus nontransmural), infarct location (anterior versus inferior), the degree of left and right ventricular dysfunction, and the frequency of ventricular dysrhythmia. Hence, at least some of the prognostic impact of these variables may be due to the initial extent of infarction sustained. Multivariate analysis has been employed by several groups to analyze the independent contribution of these clinical descriptors to prognosis after infarction. These analyses have consistently indicated a substantial independent impact of enzymatic estimates of infarct size on prognosis. In studies of patients with initial myocardial infarction, infarct size index calculated from total plasma CK time activity curves had the greatest independent influence on survival. Unfortunately, the utility of enzymatic estimates of infarction as prognostic indicators in individual patients is attenuated by alterations in the strength of the apparent association between CK infarct size and prognosis in specific clinical situations. Thrombolytic therapy is now employed with increasing frequency during acute myocardial infarction. It has become abundantly clear that plasma CK release kinetics are profoundly modified by this procedure. Peak plasma total and CK-MB activity is markedly increased compared with that of patients undergoing routine therapy for infarction, with a profoundly altered CK time activity curve.(ABSTRACT TRUNCATED AT 250 WORDS)