Frequency of transient reductions in left ventricular ejection fraction at rest in coronary artery disease

Abstract

To determine the prevalence of decreases in left ventricular (LV) ejection fraction (EF) at rest in patients with coronary artery disease (CAD), including those with stable angina (n = 21), unstable angina (n = 13), and recent myocardial infarction (n = 11), continuous assessment of LV function for 162 ± 136 minutes was performed using a new nuclear device. The results were compared with those of a group of normal subjects (n = 10) monitored for 80 ± 28 minutes. Episodes of EF reduction of >7% from baseline for a total duration of >5% monitored time occurred in 0 of 10 normal subjects; episodes were more frequent in patients with stable angina (10 of 21, 48%; p = 0.01), with recent myocardial infarction (7 of 11, 64%; p = 0.004), and with unstable angina (11 of 13, 85%; p = 0.0001). The number of EF decreases per hour in patients after myocardial infarction (1.7 ± 2.5 [SD]) and unstable angina (1.2 ± 0.7) was significantly more frequent than in normal subjects (0.3 ± 0.4), but was not different from that in patients with stable angina (0.8 ± 1.0), The duration of the decrease in EF, expressed as minutes per hour of monitored time in normal subjects (0.7 ± 1.0%), was significantly less than in patients with unstable angina (10 ± 8%). Patients with stable angina (6 ± 9%) and recent myocardial infarction (6 ± 6%) were not significantly different from normal subjects. EF decrease in normal subjects was distinguished by an increase in heart rate with a decrease in end-diastolic volume but no change in end-systolic volume, whereas patients with CAD had a lesser increase in heart rate, no change in end-diastolic volume, and a significant increase in end-systolic volume. It is concluded that transient asymptomatic episodes of LV dysfunction often occur at rest in patients with CAD and are longest in patients with unstable angina.