Does the development of Q waves affect 1-year mortality and reinfarction rates in patients with acute myocardial infarction?
In patients with acute myocardial infarction, the absence of Q waves is associated with a higher reinfarction rate but is not independently associated with 1-year mortality.
In a totally nonselected group of patients with acute myocardial infarction (AMI) (n = 921) admitted from the emergency department to the coronary care unit or other hospital ward, the occurrence of non-Q-wave AMI and the prognosis in these patients was determined and compared with those in whom Q waves were developed. Fifty-two percent had AMI without new Q waves. Patients with a non-Q-wave AMI differed from patients with Q-wave AMI, more frequently having a previous history of AMI (p less than 0.001), angina pectoris (p less than 0.01), diabetes mellitus (p less than 0.05), congestive heart failure (p less than 0.001), and a higher mean age (p less than 0.001), whereas smoking was more common in Q-wave AMI. Patients with non-Q-wave AMI had a 1-year mortality of 31% compared with 26% in Q-wave AMI (p greater than 0.2) and a reinfarction rate of 20% compared with 12% for Q-wave AMI (p less than 0.01). Among patients aged less than 75 years without a previous history of AMI, congestive heart failure, and diabetes mellitus, the 1-year mortality rate was 16% for patients with Q waves versus 15% for those without Q waves (NS). Appearance of Q waves was not independently associated with death. We conclude that in a nonselected group of patients with AMI the occurrence of a non-Q-wave AMI is much higher than previously reported. The prognosis in AMI during one year of follow-up is not associated with development of Q waves.
Karlson et al. (Fri,) studied this question.