Prolonged impairment of regional contractile function after resolution of exercise-induced angina: Evidence of myocardial stunning in patients with coronary artery disease

Background: Delayed recovery of contractile function in spite of normal perfusion (ie, 'stunning') has been described in animal models of exercise- induced myocardial ischemia. Therefore, we investigated whether stunning may result from effort angina in patients. Methods and Results: Patients with coronary artery disease underwent exercise testing combined with quantitative measurements of contractile function for up to 240 minutes after exercise determined by either measurement of regional ejection fraction (^99mTc radionuclide angiograpy; n=17, group A) or computer-assisted measurement of systolic wall thickening (n=14, group B). In the latter group, myocardial perfusion was also evaluated by ^99mTc-sestamibi tomographic imaging. Angina induced marked contractile dysfunction. Hemodynamic and ECG changes brought about by ischemia were promptly normalized. Furthermore, no perfusion defects could be detected in group B patients 30 minutes after exercise, yet contractile function remained impaired well after cessation of exercise. Thirty minutes into recovery, regional ejection function of previously ischemic areas was still 82.6±4.6% of baseline in group A (P<.05). Similarly, in group B patients, systolic thickening of previously ischemic segments was still significantly impaired 60 minutes after exercise, averaging 33.8±2.8% versus 40.5±2.7% at baseline (P<.05). Contractile impairment was fully reversible, as the functioning of previously ischemic segments normalized between 60 and 120 minutes of recovery. Conclusions: Prolonged yet ultimately reversible impairment of regional myocardial function may occur in patients after exercise-induced angina in the absence of perfusion abnormalities. These findings indicate that myocardial stunning may ensue after effort angina in patients with severe coronary artery disease.