Evaluation of the Association Between AV Block and Initial ECG in Patients with Acute Inferior Myocardial Infarction

Presence of ischemic changes on the anterior surface of heart and AV block worsen the prognosis of acute Inferior Mycocardial Infarction (MI). The rate of mortality increases with the occurrence of AV block in inferior MI.The aim of this study was to predict and diagnose acute Inferior MI in patients with AV block based on ECG and clinical features.Patients and In this cross sectional study that was conducted retrospectively, we reviewed the medical records of 500 patients with acute Inferior myocardial infarction admitted in Ardabil Bu Ali hospital during 2006-2007.196 patients were excluded because of non ST segment elevation in the inferior leads and/or lack of substantial data. In the other patients presence of artrioventricular block, diabetes melitus, hypertension, smoking, thrombolytic therapy, initial ischemic pattern (J point / R wave < 50% - pattern 1, J point / R wave ≥ 50% - pattern 2 in inferior leads II, III, avF and ischemia in anterior leads) and gender were recorded. The Chi square test was applied to compare differences between discrete variables. P value < 0.05 was considered as statistically significant. The study population included 304 patients. AV block occurred in 75 patients (24.7%) and 299 patients (75.3%) were without AV block.AV block occurred in only 17 patients (11.5%) of 148 patients with initial pattern 1 compared to 58 patients (37.2%) of 156 patients with initial pattern 2 (Pv=0.0001). 50 patients (30.7%) of the 163 patients with ischemic changes, had AV block. While AV block occurred in 25 patients of the total 141 patients without ischemic changes (17.7%) (Pv=0.011).Therefore ECG pattern 2 and ischemic changes in anterior leads were associated significantly with AV block. However significant statistical association between AV block and hypertension, diabetes melitus, smoking, thrombolytic therapy and gender was not detected. In this study, it was demonstrated that the occurrence of atrioventricular block is associated with pattern 2 in the inferior leads and anterior ischemia on initial electrocardiogram. There- fore these patients need extensive care and monitoring.