In-hospital myocardial infarction. Pre-infarction features and their correlation with short-term prognosis.

A retrospective study of 107 patients who sustained an acute myocardial infarction (AMI) during hospitalization was undertaken to assess the early prognosis of Q wave AMI (55 patients, group 1) and no-Q wave AMI (52 patients, group 2). Forty-one patients in group 1 and 31 in group 2 had documented ischaemia at rest in the period preceding AMI. The incidence of pre-infarction ischaemic attacks was similar in Q wave AMI compared with non-Q wave AMI (average daily incidence per patient 3.1 +/- 4.3 vs 3.0 +/- 4.3). A 'crescendo' pattern of pre-infarction angina was rarely observed in both groups. The incidence of post-infarction ischaemia (documented in 28 patients of group 1 and in 28 of group 2) was greater, but not significantly, in group 2 (average daily incidence per patient 1.0 +/- 2.6 vs 1.4 +/- 3.2). All patients with pre-infarction ischaemia sustained infarction in the same territory. AMI in group 1 was always symptomatic while 12 AMIs in group 2 were totally asymptomatic. Fifty patients from group 1 and 27 from group 2 were on therapy while AMI developed. Twenty-one patients from group 1 showed life threatening arrhythmias (ventricular tachycardia, ventricular fibrillation, third degree AV block or asystole) during AMI; of these, 14 did not survive the arrhythmias; they all had signs of left ventricular failure. Only one patient from group 2 had runs of ventricular tachycardia, unrelated to AMI but during pre- and post-infarction ischaemia. The overall mortality rate of Q wave AMI was 29% while no deaths occurred in the non-Q wave AMI.(ABSTRACT TRUNCATED AT 250 WORDS)