Non-invasive coronary flow reserve is correlated with microvascular integrity and myocardial viability after primary angioplasty in acute myocardial infarction

Objective: To test whether preserved coronary flow reserve (CFR) two days after reperfused acute myocardial infarction (AMI) is associated with less microvascular dysfunction (“ no-reflow” phenomenon) and is predictive of myocardial viability. Design: 24 patients with anterior AMI underwent CFR assessment in the left anterior descending coronary artery (LAD) with transthoracic echocardiography and myocardial contrast echocardiography (MCE) 48 h after primary angioplasty in the LAD (mean 4 (SD 2) and 3 (1) days, respectively). Low-dose dobutamine echocardiography was performed 6 (3) days after AMI and follow-up echocardiography at three months. Results: No-reflow extent was greater in patients with impaired CFR (< 2.5) than in those with preserved CFR (> 2.5) (55 (35)% v 11 (25)%, p < 0.001). MCE reflow was more common in patients with preserved CFR (8/12) than in those with reduced CFR (1/12, p < 0.05). Wall motion score index in the LAD territory (A-WMSI) was similar at the first echocardiography (2.14 (0.39) v 2.32 (0.47), NS), although it was better in patients with preserved CFR at dobutamine (1.38 (0.45) v 1.97 (0.67), p < 0.05) and follow-up echocardiography (1.36 (0.40) v 1.97 (0.64), p < 0.05). An inverse correlation was found between CFR and A-WMSI at dobutamine and follow-up echocardiography (r = −0.49, p = 0.016 and r = −0.55, p = 0.005) and between MCE and A-WMSI at dobutamine and follow-up echocardiography (r = −0.75, p < 0.001 and r = −0.75, p < 0.001). By multivariate analysis MCE reflow remained the only predictor of recovery at both dobutamine and follow-up echocardiography (odds ratio 1.06, 95% CI 1 to 1.1, p = 0.009). Conclusion: CFR is inversely correlated with the extent of microvascular dysfunction at MCE two days after reperfused AMI. CFR and MCE reflow early after AMI are correlated with myocardial viability at follow up.