Evaluation of myocardial viability and efficacy of reperfusion therapy by dual-SPECT using 99mTc-PYP and 201Tl in acute myocardial infarction

Dual SPECT using 99mTc-PYP and 201Tl was performed in 70 patients with acute myocardial infarction, and the ratio of overlap zone between 201Tl and 99mTc-PYP uptake in the infarcted area was determined (the Y-ratio). The Y-ratio was significantly higher in the group with redistribution in the infarcted area on exercise thallium myocardial scintigraphy in the chronic stage of infarction, as well as in the group with normal left ventricular wall motion. Thus, the Y-ratio value was apparently useful in the evaluation of myocardial viability. Patients from 60% of the Y-ratio upward are suggested that myocardial viability had been survived. When the Y-ratio was determined in 30 patients who underwent early reperfusion therapy (ICT or direct-PTCA), no significant difference was found between the ICT group and the direct-PTCA group. However, the Y-ratio was significantly higher when reperfusion was performed within 6 hours than when it was performed after 6 hours, and a significant positive correlation (r=0.63, p<0.01), was found between reperfusion time from cardiac event within 9 hours and the value of (100- the Y-ratio). In conclusion, the Y-ratio grateful appeared to be useful for the quantitative evaluation of myocardial viability in the acute stage of myocardial infarction. In addition, it appears to be important to perform reperfusion as soon as possible to improve myocardial salvage. (author)