MYOCARDIAL VIABILITY ASSESSED WITH FLUORODEOXYGLUCOSE AND PET IN PATIENTS WITH Q-WAVE MYOCARDIAL-INFARCTION RECEIVING THROMBOLYSIS - RELATIONSHIP TO CORONARY ANATOMY AND VENTRICULAR-FUNCTION

In previously thrombolysed patients, we analysed residual myocardial v iability using the PET-FDG technique and correlated its presence and e xtent to the angiographic appearance of the infarct-related vessel and left ventricular function. Thirty-six patients who had undergone intr avenous thrombolysis for acute myocardial infarction 4.8 +/- 7.2 month s previously were studied. Coronary angiography, left ventriculography , and assessment of myocardial perfusion and metabolism were all perfo rmed within 1 week. All patients exhibited perfusion defects consisten t with the clinically identified myocardial infarction site. Residual viability, as assessed by the PET-FDG technique, was present in 53% of cases. The infarct-related coronary artery was patent in 19 (53%) pat ients (TIMI grade 3, 79%); of the remaining 17 with occluded infarct-r elated arteries, 11 had collaterals to the infarct area. Significant F DG uptake was observed in 63% of patients with a patent infarct-relate d artery and in 41% of those with an occluded infarct-related artery. The same study protocol was adopted in a control group of 30 patients with myocardial infarction who did not receive thrombolysis. The numbe r of infarct-related patent vessels was significantly lower in these p atients (30 vs 53%) (TIMI grade 3, 56%), but the overall percentage of PET viability was again 53%. Qualitative analysis of the regional per fusion pattern showed that the magnitude and severity of the perfusion defect was similar in the two groups, regardless of the presence or a bsence of FDG uptake. Global left ventricular function was also simila r in the two groups. However, regional wall motion was significantly b etter in the thrombolysed patients with a patent infarct-related arter y than in those who had not received thrombolysis and whose culprit ve ssel was also patent. In conclusion, the results of our study support the notion that early recanalization of the infarct-related artery is critical for preserving left ventricular function. Although the number of patent infarct-related coronary arteries is greater and left ventr icular function is better in successfully thrombolysed patients, the r egional metabolic pattern does not apparently correlate with the paten cy of the infarct-related artery. This suggests that, in 'chronic' myo cardial infarction, residual tissue viability as assessed by fluorodeo xyglucose uptake does not necessarily correlate with coronary recanali zation.