PET PERFUSION AND VASODILATOR FUNCTION AFTER ANGIOPLASTY FOR ACUTE MYOCARDIAL-INFARCTION

The aims of this study were to validate invasive coronary Doppler flow s against noninvasive PET assessments of myocardial perfusion and to e xamine the timing and degree of regional coronary vasodilator reserve recovery in patients who are successfully reperfused with primary angi oplasty (PTCA) for acute myocardial infarction. Methods: PTCA was perf ormed in 21 consecutive patients with acute myocardial infarction; the final diameter stenosis was 25% +/- 7%. After restoration of TIMI Gra de 3 flow, all patients underwent quantitative coronary angiography an d distal Doppler coronary blood flow studies (basal and after adenosin e-induced hyperemia) in the infarct and noninfarct vessels. Regional m yocardial perfusion and vasodilator function were quantitated after in travenous adenosine infusion PET in all patients at 26 +/- 9 hr after acute PTCA. These were repeated in 17 patients 9 +/- 3 days later. Res ults: Post-PTCA resting coronary flow was 35 +/- 15 ml/min in the infa rct-related vessels and 50 +/- 24 ml/min during peak hyperemia (p < 0. 05). Coronary flow reserve (CFR) was 1.48 +/- 0.34 and 2.08 +/- 0.62 i n the infarct and noninfarct vessels, respectively (p < 0.001). Early (<36 hr) PET myocardial perfusion reserves (MPR) in the infarct and no ninfarct regions were 1.59 +/- 0.33 and 2.03 +/- 0.62 (p < 0.01). Dopp ler CFR and PET MPR were correlated in the infarct (r = 0.61, p < 0.01 )and noninfarct (r = 0.77, p < 0.0001) regions. Follow-up PET studies demonstrated improved MPR in both infarct and noninfarct regions (1.93 +/- 0.52 versus 2.54 +/- 0.97, p < 0.01). The improvement in coronary vasodilator function from the time of acute PTCA to follow-up PET in the infarct region was significant (p = 0.005). Conclusion: After succ essful mechanical revascularization by PTCA after acute myocardial inf arction, intracoronary Doppler blood flows and noninvasive PET regiona l myocardial perfusion are correlated within the wide range of reperfu sion blood flows observed in patients with contrast angiographic TIMI Grade 3 flow. Serial PET studies demonstrated a trend towards continue d improvement in the vasodilator response in infarct-related myocardia l regions after the restoration of blood flow by PTCA. PET offers the potential for accurate noninvasive serial assessment of reperfusion bl ood flow after primary angioplasty for acute myocardial infarction.