Clinical Study of the Stunned Myocardium.

Clinical features of 37 cases of stunned myocardium were studied. Mean duration of asynergy was 22.6 +/- 15.7 days. In all 11 cases of unstable angina without any significant serum creatine kinase leakage, the duration of asynergy was within 14 days. Related coronary lesions were reperfused (spontaneously or by interventional therapy) to TIMI grade II or higher. Transient Q waves were observed in 39% of all cases. Negative T waves tended to be prolonged, and persisted after disappearance of asynergy in 74% of all cases. 201Tl uptake in the stunned area varied widely between individual cases (ranging from "absent" to "normal"), although it became normal in all cases in the chronic stage. Mal-distribution of 99mTc-pyrophosphate (PYP) to the endocardial side of the stunned area was observed in 33%. In 186 cases of acute coronary syndrome, we studied whether or not reversibility of ischemia-disturbed myocardium could be predicted by simultaneous dual isotope SPECT, and found that 201Tl-uptake in the chronic stage significantly improved in the region showing absence of 99mTc-PYP accumulation or maldistribution of 99mTc-PYP to the endocardial side, while reversibility of the region showing transmural 99mTc-PYP accumulation and a dought pattern was poor. Ischemia-associated myocardial damage recovered to various degrees, and dual isotope SPECT was useful in evaluating the reversibility of such damage already at the acute stage.