Postexercise changes in ejection fraction associated with coronary artery disease.

Radionuclide measurement of left ventricular ejection fraction (LVEF) response to exercise has been proposed as a way to help identify patients with coronary artery disease (CAD). Previous studies were done using an exercise bicycle or a treadmill and showed that patients with CAD do not increase ejection fraction (EF) to the same extent as normal (control) subjects. The present studies were done using a coaxial Gamma Cor cardiac probe. Because radiocardiograms (RCG) obtained with the cardiac probe require 1/10 the dose required for a scintillation camera, serial measurements could be made before, during and following exercise. Although 3 of our 9 patients showed an unchanged and 3 showed a decreased EF at the time of maximal exercise, 3 others were able to increase their EF, and in 2 this increase occurred concomitantly with angina. Thus, not all the CAD patients could be identified by failure to increase EF in response to exercise. However, looking at the period just following exercise, one can see that most of our patients with CAD maintain or increase LVEF during the first 6 to 9 min after stopping exercise; normal (control) subjects rapidly return to the preexercise value. The normal pattern is an increase in EF during exercise followed by a prompt return toward normal after cessation of exercise. Changes of this normal pattern of EF increase and decrease occurred in all except 1 patient with CAD, and consequently provided a better indication of the presence of significant disease than the response during exercise alone.