Coronary flow reserve is impaired in infarcted as well as normal myocardium following successful PCI in patients with acute myocardial infarction

Abstract

Purpose: Data about evolution of microvascular function in the myocardium after successful percutaneous coronary intervention (PCI) are scarce. This holds true not only for the infarcted area but also for the remote zone. Insight in such data would lead to better understanding of the recovery of left ventricular function (LVF) after acute myocardial infarction (AMI). Also, it will guide interpretation of perfusion imaging early after myocardial infarction. Methods: We studied 25 patients (mean age 58±8 years, 21 men) presenting with an acute ST-elevation myocardial infarction (STEMI) after they were treated successfully by primary PCI. Using a hybrid positron-emission tomography/computed tomography (PET/CT) scanner, myocardial blood flow (MBF) was measured in the infarcted and normal remote area using [15O]H2O (at rest and during adenosine-induced hyperemia). To investigate the evolution of myocardial microvascular function, we performed scans at 5±3 days (1-week study) and 3±1 months (3-month study) after successful PCI. Results: At one week, baseline MBF was 0.95±0.18 ml/min/g in the infarct-related artery and 1.01±0.29 in the remote region (P=0.130), hyperemic MBF was 1.70±0.53 vs. 2.20±0.47 (P<0.001) and the coronary flow reserve (CFR; the ratio of the MBF after induction of hyperemia to basal blood flow) was 1.80±0.62 vs. 2.29±0.65 (P=0.001). At three months, baseline MBF was 0.80±0.16 ml/min/g in the infarct-related artery and 0.95±0.20 in the remote region (P=0.003), hyperemic MBF was 2.10±0.80 vs. 2.62±0.75 (P<0.001) and CFR was 2.68±0.96 vs. 2.86±0.87 (P=0.181 for the comparison with the infarcted region; P<0.001 for the comparison with the infarcted region at 1 week; P=0.004 for the comparison with the remote region at 1 week). Conclusion: Following successful PCI in patients with acute myocardial infarction, the coronary flow reserve is severely affected. Our findings show a transient microvascular coronary dysfunction in remote myocardium following acute myocardial infarction. This observation may have implications for imaging in an early stadium following myocardial infarction.