NATURAL-HISTORY OF THE 1ST NON-Q-WAVE MYOCARDIAL-INFARCTION IN THE PLACEBO ARM OF THE BETA-BLOCKER-HEART-ATTACK-TRIAL

Despite extensive investigation, the prognostic significance of the first non-Q wave acute myocardial infarction (AMI), when compared with Q wave AMI, remains controversial. The placebo arm of the Beta-Blocker Heart Attack Trial (BHAT) provides a unique opportunity to compare the long-term cardiac events in patients suffering from their first and uncomplicated Q wave or non-Q wave AMI. Of a total 3837 patients enrolled in the BHAT, 3375 were classifiable in terms of appearance or absence of Q waves during the prerandomization period. Of these, 1444 patients with their first AMI were randomized to placebo. Of these, 1186 experienced a Q wave AMI; the remaining 258 suffered a non-Q wave AMI. At 36 months of follow-up, the mortality was 8.4% in the Q wave AMI group and 7.4% in the non-Q wave AMI group. Sudden death was 5.4% in the Q wave AMI group and 4.7% in the non-Q wave AMI group. The reinfarction rate was 5.5% in the Q wave AMI patients and 7.4% in the non-Q wave AMI patients. More patients developed angina (44.6%) in the non-Q wave AMI group compared with 35.2% in the Q wave AMI group. Despite similar long-term cardiac event rates within the two groups, the 1-year mortality rate for patients with Q wave AMI appeared higher than in the non-Q wave AMI group, 5.2% versus 3.1%, respectively. In contrast, the rate of reinfarction appeared higher at the 12-month follow-up period in the non-Q wave AMI group, 4.7% versus 3.4%, respectively. Although statistically not different, it appeared that initially the non-Q wave AMI group had a higher reinfarction rate and a lower mortality when compared with the Q wave AMI group. However, over time there was an attenuation of these differences, suggesting a different clinical course for the two types of AMI.