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 > or =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.