Significant Association Between Neutrophil Aggregation in Aspirated Thrombus and Myocardial Damage in Patients With ST-Segment Elevation Acute Myocardial Infarction

Background This study was designed to clarify the relationship between myocardial damage and platelet-neutrophil aggregation in patients with acute myocardial infarction (AMI). Methods and Results The study group comprised 107 patients with ST-segment elevation AMI, in whom aspiration catheter was used during emergency percutaneous coronary intervention. Patients were divided into 2 groups according to the cellular density of neutrophils in the aspirated sample: group L(n=53), <= 100 neutrophils/0.025 mm(2) thrombus; group H (n=54), > 100 neutrophils/0.025 mm(2) thrombus. Myocardial blush grade (MBG) ! I and ST-segment resolution (STR) <50% were more frequently found in group H than in group L. Peak creatine kinase level tended to be higher and left ventricular ejection fraction (LVEF) at 6 months after onset was lower in group H than in group L. Multivariate analysis showed that high neutrophil density in aspirated thrombus was an independent predictor of MBG <= 1, STR <50%, and low LVEF at 6 months after onset. Conclusions Platelet-neutrophil aggregates retrieved from ruptured plaque may be associated with impaired coronary microcirculation and resultant myocardial necrosis/dysfunction. These findings underscore the clinical importance of the interaction between thrombosis and inflammation in the pathogenesis of AMI.