AGE-RELATED INCREASE IN MORTALITY AMONG PATIENTS WITH 1ST MYOCARDIAL INFARCTIONS TREATED WITH THROMBOLYSIS

Background. The overall rate of mortality due to ischemic heart diseas e is known to increase progressively with age. We evaluated the relati on between the mortality rate and age in patients with first myocardia l infarctions treated with thrombolytic therapy. Methods. We studied 9 720 patients with first infarctions who had been enrolled in the GISSI -2 trial. (This trial compared the efficacy of tissue plasminogen acti vator with that of streptokinase in patients with myocardial infarctio n.) Of these, only 35 percent had a history of angina. The relation be tween age and mortality during hospitalization and during the six mont hs after discharge was determined by unadjusted and adjusted analyses. Results. The in-hospital mortality rate was 1.9 percent among patient s 40 years old or younger, but it increased to 31.9 percent among thos e more than 80 years old; however, values for indicators of infarct si ze did not increase with age. Autopsies were performed in 20 percent o f the 772 patients who died in the hospital; the findings showed that the frequency of cardiac rupture increased from 19 percent among patie nts 60 years old or younger to 86 percent among those more than 70 yea rs old. The mortality rate for the first six months after hospital dis charge also increased significantly with age. After adjustment for con founding variables, older age continued to be significantly associated with a higher risk of in-hospital and post-discharge death. When age was introduced into a multivariate model as a continuous variable, the risk of death was estimated to increase by about 6 percent per year f or both in-hospital and six-month mortality rates. Conclusions. In pat ients with first myocardial infarctions who received thrombolytic ther apy, age was a powerful independent predictor of both in-hospital and post-discharge mortality rates. The exponential, age-related increase in the mortality rate did not appear to be explained by larger infarct s.