Time course of impaired coronary flow reserve after reperfusion in patients with acute myocardial infarction

To evaluate the time course of coronary flow reserve after reperfusion, 14 patients with a first anterior wall acute myocardial infarction who underwent successful coronary angioplasty within 6 hours after symptom onset were studied. After angioplasty, coronary flow reserve of the left anterior descending artery was measured with a coronary Doppler guidewire and intravenous dipyridamole (0.56 mg/kg over 4 minutes). Measurements were repeated at predischarge (16 ± 3 days, n = 12) and at follow-up (6 ± 3 months, n = 9). Patients with restenosis at the time of repeat catheterization were excluded. An additional 13 patients with normal angiograms served as reference patients. Coronary flow reserve was 1.33 ± 0.29 after angioplasty. It increased to 1.88 ± 0.36 at predischarge (p < 0.01) and further to 2.34 ± 0.38 at follow-up (p < 0.01 vs after angioplasty and at predischarge, respectively). However, compared with reference patients (3.15 ± 0.48), coronary flow reserve was significantly reduced in the infarct patients even at follow-up (p < 0.01). In infarct patients, the infarct region wall motion was initially −3.86 ± 0.67 SD/chord. It significantly improved to −2.07 ± 1.04 SD/chord at predischarge (p < 0.01) and to −1.67 ± 1.43 SD/chord at follow-up (p < 0.01). However, there was no significant relation between coronary flow reserve and region wall motion after angioplasty (r = 0.10), at predischarge (r = 0.35), and at follow-up (r = 0.28). Thus, coronary flow reserve is severely impaired early after reperfusion. Coronary flow reserve improves over 2 weeks, but the impairment persists at 6 months after acute myocardial infarction. The impairment of coronary flow reserve cannot be predicted by left ventricular function. Small sample size is a potential limitation of this study, and a larger study should be performed to confirm these findings.