Determinants of 6-month mortality in survivors of myocardial infarction after thrombolysis. Results of the GISSI-2 data base. The Ad hoc Working Group of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-2 Data Base

Abstract

Background: Current knowledge of risk assessment in survivors of myocardial infarction is largely based on data gathered before the advent of thrombolysis. It must be determined whether and to what extent available information and proposed criteria of prognostication are applicable in the thrombolytic era.

Methods and results: We reassessed risk prediction in the 10,219 survivors of myocardial infarction with follow-up data available (ie, 98% of the total) who had been enrolled in the GISSI-2 trial, relying on a set of prespecified variables. The 3.5% 6-month all-cause mortality rate of these patients compared with the higher value of 4.6% found in the corresponding GISSI-1 cohort, originally allocated to streptokinase therapy, indicates a 24% reduction in postdischarge 6-month mortality. On multivariate analysis (Cox model), the following variables were predictors of 6-month all-cause mortality: ineligibility for exercise test for both cardiac (relative risk [RR], 3.30; 95% confidence interval [CI], 2.36-4.62) and noncardiac reasons (RR, 3.28; 95% CI, 2.23-4.72), early left ventricular failure (RR, 2.41; 95% CI, 1.87-3.09), echocardiographic evidence of recovery phase left ventricular dysfunction (RR, 2.30; 95% CI, 1.78-2.98), advanced (more than 70 years) age (RR, 1.81; 95% CI, 1.43-2.30), electrical instability (ie, frequent and/or complex ventricular arrhythmias) (RR, 1.70; 95% CI, 1.32-2.19), late left ventricular failure (RR, 1.54; 95% CI, 1.17-2.03), previous myocardial infarction (RR, 1.47; 95% CI, 1.14-1.89), and a history of treated hypertension (RR, 1.32; 95% CI, 1.05-1.65). Early post-myocardial infarction angina, a positive exercise test, female sex, history of angina, history of insulin-dependent diabetes, and anterior site of myocardial infarction were not risk predictors. On further multivariate analysis, performed on 8315 patients with the echocardiographic indicator of left ventricular dysfunction available, only previous myocardial infarction was not retained as an independent risk predictor.

Conclusions: A decline in 6-month mortality of myocardial infarction survivors, seen within 6 hours of symptom onset, has been observed in recent years. Ineligibility for exercise test, early left ventricular failure, and recovery-phase left ventricular dysfunction are the most powerful (RR, > 2) predictors of 6-month mortality among patients recovering from myocardial infarction after thrombolysis. Qualitative variables reflecting residual myocardial ischemia do not appear to be risk predictors. The lack of an independent adverse influence of early post-myocardial infarction angina on 6-month survival represents a major difference between this study and those of the prethrombolytic era.