Comparision of coronary angiographic findings of ST-segment elevation and non-ST elevation myocardial infarction patients with totally occluded infarct related artery

Acute myocardial infarction is one of the leading causes of death in our country and in the world. Current myocardial infarction classification is based on ST-segment elevation seen on electrocardiography and introduces two types of myocardial infarction as ST-segment elevation myocardial infarction(STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI). It?s generally assumed that infarct related artery (IRA) is totally occluded in STEMI and subtotally occluded in NSTEMI patients. However, some patients develop NSTEMI instead of STEMI despite having a totally occluded IRA. Presence of good collateral circulation and myocardial infarctions in electrocardiographic silent areas are suggested as possible causes of this situation but the exact cause was not established clearly.The aim of this study was to compare coronary angiographic findings of acute myocardial infarction patients with totally occluded IRA which developed NSTEMI and STEMI.Coronary angiographic findings of patients diagnosed as first myocardial infarction between May 2004 and April 2010 were retrospectively analysed. Patients who have a diagnosis of NSTEMİ with a totally occluded IRA were selected. Patients with indeterminate IRA on coronary angiography, history of coronary artery by-pass graft surgery or percutaneous coronary intervention were excluded from the study. Fifty NSTEMI patients were found to meet these criteria. For each NSTEMI patient a STEMI patient was selected according to age, gender, coronary artery disease risk factors and serum creatinin level. Coronary angiography films were seen, coronary segments with atherosclerotic lesions were recorded and Gensini scores were calculated for every patient. Collateral circulation were also evaluated. Rentrop?s collateral grade 0 and 1 were regarded as poor collateral growth while Rentrop 2 and 3 were regarded as good.18,9 percent of NSTEMI patients were found to have a totally occluded IRA.Eighty percent of patients were male and mean age was 61,2 in both NSTEMI and STEMI groups. Rates of diabetes mellitus, hypertension, smoking and family history for coronary artery disease were similar between groups becaouse of the coupling made during patient selection. Serum LDL and HDL levels were also similar. Leucocyte count, CK, CK-MB and BUN levels were significantly higher and left ventricular ejection fraction were significantly lower in STEMI group, possibly due to bigger infarct size and more frequent transmural infarction in this group. New onset pathological Q waves were found in 12 percent of NSTEMI patients and 96 percent of STEMI patients.Right coronary artery was the most frequent infarct related artery in both NSTEMI and STEMI groups. Circumflex coronary artery was found significantly more frequently as IRA in NSTEMI group than STEMI group. Mean Gensini score was found signigicantly higher in NSTEMI group. Patients with good collateral circulation (Rentrop?s collateral grade 2 and 3) were found significantly more frequent in NSTEMI group (% 78 vs. % 36).In our study, the most important difference between NSTEMI and STEMI patients was good collateral growth seen in NSTEMI patients. It also seems that total occlusions in circumflex coronary artery more likely to cause NSTEMI instead of STEMI. Good collateral circulation possibly protects myocardium and a non-transmural infarction develops instead of a transmural one. Larger studies are required to clarify the importance of total occlusions in NSTEMI patients