Pressure-derived collateral flow index: a strong predictor of late left ventricular remodeling after thrombolysis for acute myocardial infarction

Despite proved efficacy of pressure-derived collateral flow index in determining microvascular dysfunction in patients with acute myocardial infarction, its role in prediction of left ventricular remodeling at long term has yet to be demonstrated. In this study, we investigated the relationship between quantitatively assessed microvascular dysfunction by using intracoronary pressure wire and late left ventricular remodeling. The study population consisted of 28 patients with first acute myocardial infarction. They were treated with fibrinolytic therapy. The inclusion criteria were thrombolysis in myocardial infarction grade II-III flow in infarct-related artery and all destined for stent implantation. Cardiac catheterization and stent implantation were performed in mean of 3.3 days after acute myocardial infarction. During the stent implantation procedure, the pressure-derived collateral flow index was measured by using intracoronary pressure wire. Control angiograms were performed at 6 +/- 2 months. Echocardiographic left ventricular volume indexes were measured at discharge, at 6 months and at 1 year. Changes in left ventricular volumes from baseline to 1 year were followed. Left ventricular end-diastolic volume index at 1 year correlated significantly with the pressure-derived collateral flow index (r = 0.69, P < 0.01). A significant correlation was also observed between the change in left ventricular end-diastolic volume index from baseline to 1 year and the pressure-derived collateral flow index (r = 0.65, P < 0.01). The most important predictor of 1-year left ventricular remodeling was the pressure-derived collateral flow index (P < 0.0001), and collateral circulation (P = 0.03). The pressure-derived collateral flow index is a powerful independent predictor of 1-year left ventricular dilatation. Given its simplicity of measurement, and correlation with microvascular obstruction and left ventricular outcome at long term, the pressure-derived collateral flow index may provide useful and valuable estimates of clinical outcomes after acute myocardial infarction.