Non-Q wave myocardial infarction: recent changes in occurrence and prognosis--a community-wide perspective

A community-wide study of patients hospitalized with validated acute myocardial infarction (MI) in all 16 hospitals in the Worcester metropolitan area, during the calendar years 1975, 1978, and 1981, is examining time trends in the incidence rates, in-hospital case fatality rates, and long-term survival rates of 2451 patients hospitalized with acute MI further classified into those with Q wave and those with non-Q wave MI. The age-adjusted hospital attack rates (per 100,000) of initial events of Q wave MI increased from 153 in 1975 to 197 in 1981 (p less than 0.05), while the attack rates of non-Q wave MI increased from 46 in 1975 to 89 in 1981 (p less than 0.001). Patients with non-Q wave MI were at significantly decreased risk of dying during hospitalization (12.0%) as compared to those with Q wave MI (25.2%), overall as well as for each of the three time periods studied (p less than 0.05). For patients discharged alive from the hospital, however, there were no significant differences in long-term survival rates according to MI type over an 8-year follow-up period. These results, obtained from a community-wide sample of patients with validated acute MI, indicate a significant change in the occurrence rates and/or recognition of non-Q wave MI, a significantly lower in-hospital case fatality rate for patients with non-Q wave MI, and comparable long-term prognosis for patients with Q wave and non-Q wave acute MI.