Ischemia on effort is not a determinant of stunned myocardium in man: a radioisotopic study based on quantitative evaluation of ventricular dynamics.

To assess whether myocardial stunning occurs following brief episodes of effort ischemia, ventricular function was assessed by radionuclide angiography in 29 patients with coronary artery disease. No patient had evidence of previous myocardial infarction. Patients were divided into two groups according to presence of single (14 patients, Group 1) or multi-vessel (15 patients, Group 2) coronary artery disease. Equilibrium radionuclide angiocardiography was performed in the left anterior oblique projection by a small field-of-view gamma-camera. Acquisition were performed at baseline, at peak exercise, then again at 1 and 5 minutes of the recovery phase. For each acquisition, ejection fraction, peak filling rate and wall motion index were measured and compared. No difference in baseline and stress measurements was found between Group 1 and Group 2, except for the wall motion index that was more impaired during ischemia in patients of Group 2. Global and regional indexes of ventricular function did not show significant differences also in the two recovery periods when compared to the relative baseline values. Transient ischemia caused by an increase of oxygen demand did not reproduce the phenomenon of systolic and diastolic stunning observed in animal experiments, although in all patients the ischemia was of sufficient duration and severity to induce transient ventricular dysfunction.