Asymptomatic myocardial ischemia in patients with stable and typical angina pectoris.

Abstract

AbstractThe existence of transient myocardial ischemia (TMI) and the value of the serial dynamic electrocardiogram (DCG) in patients with variant or unstable angina pectoris are known. However, less information is available on the frequency and characteristics of TMI in patients with stable angina pectoris. For this study, we selected 40 patients with stable and typical angina pectoris. The presence of coronary artery disease and the ejection fraction were evaluated by means of angiocardiography. The DCG monitoring was performed with bichannel portable recorders for three 24‐h periods at 7‐day intervals. The patients were on optimal doses of beta blockers and isosorbidilate throughout the study. We detected 788 episodes of TMI in 22 of the 40 patients. The ejection fraction was poorer in the 22 patients with ST‐T changes than in the 18 without such changes. The repolarization changes were: (1) ST elevation (55 symptomatic and 87 asymptomatic episodes, (2) ST depression (138 symptomatic and 236 asymptomatic episodes, and (3) T‐wave changes (83 symptomatic and 164 asymptomatic episodes). All 22 patients with TMI presented a combination of the above changes. It appears, therefore, that ST‐T changes are more frequent in patients with stable angina pectoris than was hitherto suspected. The DCG is valuable in assessing these changes, especially when one considers that the asymptomatic episodes are almost twice as frequent as the symptomatic ones. The asymptomatic episodes lasted a mean of 1.8±1.3 min (mean±SD), while the symptomatic episodes lasted 3.8±2.7 min (p <0.02, by sign test). Heart rate was unchanged during the episodes of TMI, and did not show any significant difference between asymptomatic and symptomatic episodes. Additional investigation is necessary, however, to determine the clinical implications of these findings.