Abnormal Responses of the Systolic Time Intervals to Exercise in Patients with Angina Pectoris

Abstract

The effects of a 4-min exercise on the duration of the systolic time intervals were determined in 20 patients with angina and 20 age-matched normal controls. The pre-ejection period was shortened 26 msec in normal subjects and 35 msec in angina patients. In normal subjects, total electromechanical systole corrected for heart rate (Q 2 2c ) decreased 24 msec, while the left ventricular ejection time corrected for heart rate (LVET c ) remained unchanged. In the angina group, by contrast, Q 2 2c failed to change, while LVET c lengthened 23 msec. The angina patients developed similar abnormalities, without pain, after 2 min of exercise. Changes in arterial pressure, cardiac output, and stroke volume failed to explain these systolic temporal abnormalities. Similar abnormalities occurred in 12 patients with primary myocardial disease and heart failure, but not in seven noncardiac patients with nonanginal chest pain. Owing to impaired left ventricular performance and increased afterload, mild exercise prolongs left ventricular ejection in patients with angina. This abnormal prolongation contributes to the development of angina and has value in its diagnosis.