Exercise-induced stunning continues for at least one hour: evaluation withquantitative gated single-photon emission tomography

To elucidate the after-effect of exercise on left ventricular (LV) function , end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fracti on (LVEF) were evaluated at 1 h after exercise and at rest by technetium-99 m tetrofosmin gated myocardial single-photon emission tomography (SPET) usi ng an automated program in 53 subjects. The subjects were grouped as follow s: normal scan (n = 16), ischaemia (n = 19) and infarction (n = Is), based on the interpretation of perfusion images. Postexercise LVEF did not differ from resting LVEF in the groups with normal scan and infarction. In patien ts with ischaemia, postexercise EDV (90+/-17 mi, mean +/-SD) and ESV (44+/- 15 mi) were significantly higher than EDV (84+/-15 mi, P = 0.001) and ESV ( 36+/-14 mi, P<0.0005) at rest, LVEF was si,significantly depressed 1 h afte r exercise (53%+/-9% vs 58%+/-9%, P<0.0001). In ischaemic patients with dep ressed postexercise LVEF LVEF difference between rest and postexercise show ed a significant correlation with the sum of defect scores, which were reve rsible from exercise to rest perfusion images (r = 0.92, P<0.0001). These r esults indicate that exercise-induced LV dysfunction (myocardial stunning) continues for at least 1 h in ischaemic patients and that the extent of LVE F depression is determined by the severity of ischaemia.