Prognostic value of predischarge exercise testing, ejection fraction, and ventricular ectopic activity in acute myocardial infarction treated with streptokinase

Abstract

The relative importance of prognostic parameters that delineate left ventricular function, myocardial ischemia, and arrhythmogenic potential after thrombolytic therapy is not clear. This study investigated 112 patients with acute myocardial infarction who were treated with thrombolysis to determine the relative prognostic value of predischarge treadmill exercise testing, radionuclide ventriculography, and ambulatory electrocardiographic monitoring for ventricular ectopic activity. During a mean follow-up period of 18 months (range 6 to 30), 42 first cardiac events were recorded, consisting of 3 deaths, 6 reinfarctions, 16 bouts of unstable angina, 16 episodes of heart failure, and 1 arrhythmic event. Univariate analysis revealed ejection fraction, exercise time, and ventricular ectopic count of > or = 10/hour to be predictive of future cardiac events. Subsequent multivariate analysis showed ejection fraction (p <0.001) and exercise time (p=0.002 to have independent prognostic value, but ventricular ectopic activity did not provide additional information. Ventricular ectopic count > or = 10/hour was additionally predictive only when combined with either ejection fraction (R2=5.4%) or exercise time (R2=2.9%). Event-free survival analysis revealed hazard ratios for ejection fraction <40% and exercise time <7 minutes of 3.63 (p=0.001) and 2.16 (p=0.01), respectively. Although ejection fraction and exercise time were able to predict future episodes of heart failure, neither could adequately identify patients at risk of recurrent ischemic events.