Impact of microvascular dysfunction on left ventricular remodeling and long-term clinical outcome after primary coronary angioplasty for acute myocardial infarction

Background - We hypothesized that preserved microvascular integrity in the area at risk would favorably influence left ventricular (LV) remodeling and long-term outcome after acute myocardial infarction. Methods and Results - Before and after successful primary angioplasty ( percutaneous transluminal coronary angioplasty [ PTCA]), 124 patients with acute myocardial infarction underwent intracoronary myocardial contrast echo (MCE). An MCE score index (MCESI) was derived by averaging the single-segment score ( 0 = not visible, 1 = patchy, 2 = homogeneous contrast effect) within the area at risk. An MCESI greater than or equal to 1 was considered adequate reperfusion. Mean follow-up was 46 +/- 32 months. After PTCA, 100 patients showed adequate reperfusion ( no microvascular dysfunction, NoMD), whereas 24 did not ( MD). MD patients had a higher mean creatine kinase ( 4153 +/- 2422 versus 2743 +/- 1774 U/L; P = 0.002) and baseline wall-motion score index ( 2.61 +/- 0.31 versus 2.25 +/- 0.42; P < 0.001) and a lower baseline ejection fraction ( 33 +/- 8% versus 40 +/- 7%; P < 0.001). From day 1 on, LV volumes progressively increased in the MD patients ( n = 19) and were larger than those of NoMD patients ( n = 85) at 6 months (end-diastolic volume 170 +/- 55 versus 115 +/- 29 mL; P < 0.001). MCESI was the most important independent predictor of LV dilation ( OR 0.61, 95% CI 0.52 to 0.71, P < 0.000001). By Cox analysis, MD represented the only predictor of cardiac death ( OR 0.26, 95% CI 0.09 to 0.72, P = 0.010) and combined events ( cardiac death, reinfarction, and heart failure; OR 0.44, 95% CI 0.23 to 0.85, P = 0.014). MD patients showed worse survival in terms of cardiac death ( P < 0.0001) and combined events ( P < 0.0001). Conclusions - In reperfused acute myocardial infarction, MD within the risk area is an important predictor of both LV remodeling and unfavorable long-term outcome.