Continuous monitoring of left ventricular function by an ambulatory radionuclide detector in patients with coronary artery disease.

Global left ventricular function and a modified V5 electrocardiographic (ECG) lead were continuously monitored by a radionuclide recorder in 12 normal subjects and 39 patients with coronary artery disease while the subjects were performing various daily activities. The ambulatory studies revealed that walking on a level surface caused 11 of 12 normal subjects and 18 of 32 patients to increase their left ventricular ejection fraction by greater than 6% units. A transient decrease in left ventricular ejection fraction (6 to 18%) lasting greater than or equal to 1 min was observed on 36 occasions in 16 patients with coronary artery disease; 12 episodes were accompanied by chest pain or shortness of breath and 24 were asymptomatic. Electrocardiographic ST segment depression suggestive of ischemia was recorded in 6 of the 12 symptomatic and 5 of the 24 asymptomatic episodes. In 10 of the 12 symptomatic episodes, left ventricular ejection fraction began to decrease 30 to 90 s before the onset of symptoms. These studies suggest that continuous monitoring of both left ventricular function and the ECG may permit stratification of episodes of ST depression suggesting ischemia by the degree of left ventricular dysfunction they produce.