Pressure-derived collateral flow index as a parameter of microvascular dysfunction in acute myocardial infarction

Objectives The goal of this study was to examine the implications of the pr essure-derived collateral flow index (CFIp) in acute myocardial infarction (AMI). Background Higher CFIp is associated with less severe myocardial ischemia d uring angioplasty in the non-infarcted heart. It remains unknown whether CF Ip also identifies collateral function in AMI patients with and without no- reflow phenomenon. Methods The study population included 48 patients with a first AMI. After s uccessful percutaneous transluminal coronary, angioplasty (PTCA) stent, we measured mean aortic pressure (Pa), central venous pressure (Pv) and corona ry wedge pressure (Pew) of the infarct-related artery to calculate: CFIp = (Pcw - Pv)/(Pa - Pv). Myocardial contrast echocardiography (MCE) was perfor med with the intracoronary, injection of microbubbles to assess myocardial perfusion. Left ventriculograms at days 1 and 28 were provided for the meas urement of the regional wall motion (RWM, SD/chord). Results There was no difference in CFIp among subsets based on angiographic collateral grades (grade 0, 1, 2, 3; 0.28 +/-0.07, 0.27 +/-0.09, 0.27 +/-0 .08, 0.23 +/-0.08, p=NS). The CFIp was significantly higher in patients wit h NICE no-reflow (n=16) than in those with MCE reflow (n=32) (0.34 +/-0.07 vs. 0.23 +/-0.06, p<0.01). There was a significant inverse correlation betw een the extent of functional improvement (<Delta>RWM[28 d-1 d]) and CFIp (r =0.56, p<0.01), implying that higher CFIp is associated with worse function al improvement. Conclusions In AMI, CFIp is unlikely to reflect collateral function but see ms to increase with the severity of microvascular dysfunction. Because high er CFIp was associated with poorer functional recovery, it provides a simpl e and useful estimate of clinical outcomes in AMI. (J Am Coll Cardiol 2001; 38:1383-9) (C) 2001 by the American College of Cardiology.