Role Of Early Collateral Circulation In The Acute Phase Of ST-segment-elevation Anterior Myocardial Infarction Treated With Primary Coronary Intervention

BackgroundAmong patients with acute myocardial infarction(AMI), infarct size is a major determinant of subsequent left ventricular remodeling and subsequent mortality. Infarct size is directly related to myocardial area at risk which can be influenced by the presence of collateral circulation to the infarct-related artery (IRA). Collatera flow can also prolong the maximal time of coronary occlusion before reperfusion when irreversible transmural myonecrosis develops. Collateral circulation may predate or develop early (within minutes) after loss of arterial patency and is more common in younger patients and those with a history of preinfarction angina and nonanterior myocardial infarction.The role of collateral circulation to the myocardium at risk in the setting of acute coronary occlusion has been of special interest in the last decades. The coronary collateral circulation has long been recognized as an alternative source of blood supply to a myocardial area jeopardized by ischemia. Well-grown versus poorly grown collateral arteries in humans have been suggested to exert a beneficial effect on infarct size, ventricular aneurysm formation, and ventricular function. A reduction in nonfatal cardiovascular events during various follow-up durations has been demonstrated among patients with versus those without angiographic coronary collaterals in the setting of chronic stable coronary artery disease.Animal studies have shown that collateral flow has a protective effect on infarct size in terms of reducing the area at risk.In humans, angiographic studies after thrombolytic therapy has shown better preserved left ventricular function in patients who responded to failure of reperfusion therapy with early collateral flow. In a selected population of patients with anterior myocardial infarction, angiographic evidence of collateral circulation was associated with better haemodynamics at presentation and lower in-hospital mortality.Other studiesshowed no clinical benefit of early collateral circulation in acute myocardial infarction treated with primary percutaneous coronary intervention (PCI).Coronary collateral flow may be identified by several different techniques. We studied coronary collateral flow as detected by angiography because it is easy to incorporate into the routine clinical practice of acute myocardial infarction treatment with PCI. Our aim was to determine whether early angiographic evidence of collateral circulation is related to infarct size, prognosis in patients in the acute phase of ST-segment-elevation anterior myocardial infarction treated with PCI within12h of the onset of symptoms.ObjectiveWe try to study the role of early collateral circulation in the acute phase of ST-segment-elevation anterior myocardial infarction treated with primary percutaneous coronary intervention, thus providing clinical evidence for the application of coronary collateral circulation.Method1.Clinical dataA total of132patients with ST-segment-elevation anterior myocardial infarction were enrolled from September2008to September2012, which meet the following criteria. All the patients were treated with PCI. According to the Rentrop grade we divided these patients into2groups:A group(non-collateral circulation group---Rentrop0grade, n=91)and B group(collateral circulation group---Rentrop1,2,3grade, n=41). All the operations were done by sophisticated cardiologist of Zhujiang Hospital of Southern Medical University with good experience in PCI to attenuate deviations of different operators. In each group, we collect clinical information detailed included:detailed medical records, major adverse cardiac events, complication and clinical outcome.1.1Inclusion criteria(1) Meet the diagnostic criteria of ST-segment-elevation anterior myocardial infarction:①symptoms of acute myocardial infarction lasting more than30min, not relieved by taking nitroglycerin;②with more than1mm (0.1mV) ST-segment elevation in two or more contiguous electrocardiographic chest leads;③abnormal myocardial injury marker with a dynamic process;(2) Coronary angiography confirmed to be anterior descending branch related infarction with TIMI0-1.(3) Treated with PCI within12hours.1.2Exclusion criteria(1) Patients with advanced neoplastic disease;(2) On end-stages of disease such as multiple organ dysfunction syndrome, uremia and so on;(3) The history of old myocardial infarction;(4) Severe valvular hear disease, dilated and hypertropic cardiomyopathy;(5) Treated with thrombolysis before PCI.1.3Evaluation indexThe evaluation index includes:Killip classification, postoperative LVEF, major adverse cardiac events, Complications of myocardial infarction, postoperation hospitalization duration.2. Statistical methodAll the data underwent statistics test by SPSS19.0software. Continuous baseline and outcome variables are presented as mean±SD, the differences between groups have been compared by means of the T-test, whereas discrete variables are expressed as absolute values and percentages, compared by means of the chi-square test. Differences for the main effects were considered statistically significant at p<0.05(two-sided test).3.Results1.General conditions of two groups:age(62.13±14.39VS64.76±13.68)years, triglyceride (1.54±0.85VS1.26±0.72) mmol/L,LDL(3.25±1.18VS3.10±1.09)mmol/L, ischemic time (6.99±3.56VS7.72±2.08) h, time of operation(69.10±20.90VS66.34±27.46)min, creatinine (64.87±15.85VS67.93±14.58)mmol/L, blood glucose level (9.14±4.41VS8.22±3.54) mmol/L, The percentage of males(80.2%VS85.4%), DM(16.5%VS12.2%), smoking history(44.0%VS43.9%), slow reflow during PCI(8.8%VS9.8%). These data are comparative without statistical significance (P>0.05).2.The data with a remarkable difference (P<0.05):The proportions of hypertension, preinfarction angina, multivessel disease, MACE/Complication and Killip classification≧2were Respectively45.1%VS26.8%(x2=3.933, P=0.047),41.8%VS61.0%(x2=4.184,P=0.041),37.4%VS56.1%(x2=4.044,P=0.044),44%VS24.4%(x2=4.598, P=0.032),67.0%VS42.9%(x2=3.972, P=0.046), total cholesterol (5.24±0.99VS4.44±1.31) mmol/L (t=3.849, P=0.000), postoperation hospitalization duration (7.97±2.59VS6.59±1.87) d (t=3.080, P=0.003), LVEF (40.34%±8.54%VS44.71%±8.12%)(t=-2.760, P=0.007)ConclusionsFor the patients in the acute phase of ST-segment-elevation anterior myocardial infarction treated with PCI:1. There was no significant difference between A and B group about age, sex, DM and smoking history.2. The history of hypertension means a poor collateral circulation, while preinfarction angina suggests well-developed collaterals.3. Total cholesterol may inhibit the development of collaterals, while LDL and TG had no effect. 4. Severity of coronary artery disease is more complicated in STEMI patients with collateral circulations.5. The AMI patients who have collateral circulation are inclined to suffer multivessel lesions and complicated lesions, while collateral circulation have benefit on infarction area and left ventricular function.