Abstract
Four hundred and seventy-six patients with acute myocardial infarction (AMI) were
interviewed to evaluate the clinical features of angina before AMI. Two hundred and
sixty-six of the 476 patients had angina before AMI, of which 137 had new onset of
angina within 2 months before AMI, and 129 had chronic angina of more than 2 months
before AMI. Forty of the 129 chronic angina patients noted worsening of symptoms within
2 months before AMI. Of the 177 patients with new onset angina or worsening angina
such as unstable angina, the incidence of new onset angina was higher than that of
worsening angina. Twenty-eight (70%) of the 40 patients with worsening of symptoms
had started with effort angina, 16 of whom turned to resting angina from effort angina
at the onset of unstable angina in spite of the fact that 12 had worsening of effort
angina. Of the 137 patients with new onset angina, 65 (40%) started with resting angina
and 72 (53%) with exertional angina. In the former group, 43 (66%) developed AMI within
1 week after the onset of angina, which was greater than 19 (26%) in the latter group.
These results may suggest that the appearance of the resting angina would herald AMI
in both groups of unstable angina. The onset of resting angina in the group of new
onset angina could be the warning of AMI development within a shorter interval than
those of exertional angina.
