| Objectives:Recent clinical observations showed that compared to patients with permanent occlusion of infarct related artery, acute myocardial infarction (AMI) patients with spontaneous reperfusion (SR) have better prognosis. Although SR is an important clinical issue during percutaneous coronary intervention (PCI), which is vital during decision-making for an individualized reperfusion strategy in the catheter lab, few studies have evaluated the potential mechanisms underlying this phenomenon. Therefore, the present study was sought to investigate:1) general clinical characteristics of AMI patients with and without SR (NSR group); 2) endothelial function in these two groups; 3) inflammatory response, focusing on pregnancy-associated plasma protein-A (PAPP-A) and OX40 ligand (OX40L) levels in systemic and coronary circulation; 4) coronary plaque features in infarct related arteries revealed by gray scale and virtual histology (VH) intravascular ultrasound (IVUS).Materials and Methods:From Mar 2008 to Jun 2010, thirty ST segment elevation MI (STEMI) patients with a TIMI grade of 2-3 during coronary angiography (CAG) were consecutively enrolled to SR group. Another thirty age and sex matched STEMI patients with a TMI grade of 0-1 were enrolled to NSR group. All patients were provided with informed consent, and were scheduled for direct PCI. Flow mediated dilation (FMD) of brachial artery and echocardiography were evaluated at bedside. During direct PCI procedure, blood from infarcted related artery (IRA) was sucked with Zeek catheter, and then IVUS was performed. Nitric oxide (NO), endothelin (ET), PAPP-A and OX40L levels in coronary suctions were determined by ELISA. Total RNA was extracted from coronary suctions to determine PAPP-A and OX40L mRNA expression levels by real-time quantitative PCR. Major cardiovascular events (MACE) including death, re-MI and target vessel revascularization (TVR) and echocardiographic changes were followed up at six month after direct PCI.Results:Smoking rate, plasma levels of total cholesterol, cTnl and glucose in NSR group was higher than those in SR group (P＜0.05). Left ventricular ejection fraction (EF) in SR group was higher than that in NSR group at six month from PCI (P<0.05). SR group exhibited an improved left ventricular ejection fraction (LVEF,45.59±8.21 vs.40.30±7.06, P＜0.05) compared with NSR group in 6 month follow-up. Compared with NSR group, SR group had higher coronary NO concentration (50.65±13.67 umol/mL vs.28.83±12.19μmol/mL, P<0.05), lower coronary ET level (63.49±10.58 umol/mL vs.92.51±16.35μmol/mL, P＜0.05), and higher brachial artery FMD (8.49±2.36% vs.4.68±1.75%, P＜0.05). Coronary concentration of PAPP-A was significantly reduced in SR group (0.54±0.22 ng/mL vs.0.94±0.33 ng/mL, P<0.01) compared with NSR group. This change was paralleled with the change of mRNA level in coronary extractions (4.19±3.20 AU. Vs.8.10±3.48 AU., P＜0.05). No difference of OX40L protein and mRNA levels in SR and NSR group was noted. There is a striking difference between the structure of infarct related artery revealed by gray scale IVUS in SR and NSR groups, in terms of lumen area (LA), percent atheroma volume (PAV), eccentricity index (EI) and remodeling (RI) index (all P＜0.05). No difference of vessel area (VA) was observed between groups. Using VH-IVUS technique, compared with NSR group, coronary plaques of SR group is composed of less fibro-fatty (FF) tissue (P<0.01) and necrotic core (NC) (P＜0.01), more dense calcium (DC, P<0.05), and decreased NC/DC ratio of (P<0.01). Bivariate coefficient analysis revealed that FF (r=.42, P<0.05 for PAPP-A; r=0.31, P＜0.05 for OX40L), NC (r=0.28, P＜0.05 for PAPP-A; r=0.56, P＜0.01 for OX40L) and NC/DC ratio (r=0.33, P＜0.05 for PAPP-A; r=0.63, P＜0.01 for OX40L) were significantly correlated with PAPP-A and OX40L coronary levels.Conclusions:Our results showed that spontaneous reperfusion in infarct related artery after AMI may be ascribed to improved endothelial function, lower coronary PAPP-A level, and more stabilized coronary plaque morphology compared with patients without spontaneous reperfusion. |
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