MARKERS OF LEFT-VENTRICULAR DYSFUNCTION INDUCED BY EXERCISE, DIPYRIDAMOLE OR COMBINED STRESS ON ECG-GATED MYOCARDIAL PERFUSION SCANS

An index of left ventricular contraction can be extracted from the cavitary time-activity curve of electrocardiographic (ECG)-gated myocardial perfusion scans. To assess the induction of stress-induced myocardial depression, we compared contraction indexes derived from immediate poststress and delayed Tl-201 images with indexes of ventricular dilation and lung uptake in the prediction of severe coronary artery disease (defined as two or more 90% stenoses). Stress procedures were performed in 93 patients with symptom-limited supine bicycle exercise alone, and in 227 with intravenous dipyridamole, combined where possible with exercise. The immediate and delayed contraction indexes reflected left ventricular dysfunction on ventriculography (P<0.0001), but additionally the immediate index was reduced (P<0.0001) in severe coronary disease. Stress-induced hypokinesis was seen frequently after each of the tes t modes. The relationship with angiographic findings was better defined for indexes of contraction than for lung uptake or ventricular dilation (P<0.01). The prediction of severe coronary disease was optimized by combining the poststress contraction index and lung uptake. These data support the use of ECG-gated myocardial scans in evaluating the functional consequences of stress/imaging procedures.