Abstract

Elevation of ST segment in right sided chest leads V3R/V4R, which is commonly encountered in right ventricular myocardial infarction during acute inferior wall myocardial infarction, may also occur in patients with anterior STEMI. However, the clinical impact of this finding in the setting of anterior myocardial infarction has not been thoroughly investigated. This study aimed to investigate the correlation between the conus branch of right coronary artery and the pattern of ST-segment elevation in lead V1 and right sided chest leads V3R and/or V4R during acute anterior wall myocardial infarction and the in hospital outcome of this finding. Objectives: This study aimed to investigate the impact of the size and course of the right coronary artery conus branch and the pattern of ST segment elevation in leads V1 and V3R in patients with acute anterior myocardial infarction and also the prognostic value of the conus branch was assessed by the in hospital outcome of those patients. Methods: Patients with acute anterior myocardial infarction, upon admission, a standard 12 leads ECG with additional right sided chest leads V3R and V4R were obtained and coronary angiography performed within 48 hours of onset of chest pain. Patients were selected purposively after meeting the inclusion and exclusion criteria. A total ninety patients were selected and were allocated into two groups, 45 patients in each group based on the size and course ofthe conus branch; either large (≥0.5mm, reaching IVS) or small (<0.5mm, not reaching IVS). ECG and angiographic findings, as well as in hospital clinical outcome including heart failure, arrythmia, conduction disturbances, death and MACEwere compared between two groups. The statistical tests of significance including chi-square, fisher’s exact and unpaired t- test were done as appropriate. Results: ST segment elevation in right-sided leads and heart failure were significantly higher inthe small conus branch group than the large conus branch group (91.1% vs24.4%, P<0.001 and 64.4%vs 20.0%, P<0.001 respectively). The presence of small conus branch was associated with significantly lower LVEF than large conus branch (43.62±3.31vs 46.02±4.03, P=0.003). There was no significant difference in mortality, arrythmia and conduction disturbance between the two groups. There was a significant difference in MACE between the two groups (64.4% in small conus group vs22.2% in large conus group, P<0.001). Conclusion: In patients with anterior MI, small conus branch was associated with higher rates of major adverse cardiac events mostly because of increased rate of acute heart failure. The presence of a large conus branch can protect the right side of the interventricular septum during left anterior descending artery occlusion in acute anterior myocardial infarction

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