The Relation Between Coronary Arterial Stenosis And Acute Myocardial Infarction

Acute myocardial infarction (AMI) is due to coronary occlusion on the basis of vulnerable plaque rupture and secondary thrombosis. It is widely believed that mild or moderate luminal stenosis represents a higher risk for AMI than anatomically and physiologically severe lesions. This, however, is in contradiction with experience from interventional practice in primary PCI.Objective:To access the underlying stenosis severity of the culprit lesion in patients with AMI.Methods:From Jan 2003 to Aug 2009,171 hospitalized patients with AMI were analyzed retrospectively and the following criteria were met:(1) onset of symptoms >30 minutes and nitroglycerin can't relieve it; (2) ST elevation>≥2mm in 2 contiguous precordial leads or≥1mm in 2 contiguous limb leads or new left branch bundle block; (3)full doses of antithrombotic drugs immediately after admission (chew aspirin 300mg and take clopidogrel 300-600mg) and essential drug therapy for at least 6 days before angiography (aspirin, clopidogrel, low molecular weight heparin, statins, etc); (4) angiography was performed within 6-30 days after the onset of symptoms of AMI; (5) with electrocardiographic and coronary angiogram, there is evidence that all patients reflowed the culprit lesion, involving both spontaneously and after passage of guidewire or balloon, but pre-balloon expansion. Moreover, Judkins, a conventional positioning projection, was taken and quantitative coronary angiography (QCA) was performed to estimate the stenosis severity by two experienced experts. Statistical analysis was performed using Graphpad Prism 5.0 Software. Continuous variables were presented as mean±SD. Categorical variables were expressed as frequencies and percentages. One-way analysis of variance and post hoc analysis using Bonferroni's test were applied to assess statistical significance in continuous variables. A p values<0.05 was considered statistically significant.Results:171 AMI patients were divided into three groups by QCA:mild, moderate and severe group (coronary artery diameter stenosis severity was<≤50%, 50～70%,>70% respectively). Of these patients,160 (93.57%) presented with a stenosis>70%. The average diameter stenosis percentage of left anterior descending (LAD), left circumflex (LCX) and right coronary artery (RCA) was (84±21)%, (82±31)% and (81±32)% respectively, and there were no significant differences among them (P>0.05).Conclusion:The majority of acute myocardial infarctions occur in severe coronary stenosis. Diameter stenosis severity was≤70% in a minority of cases.