ABSTRACT
BACKGROUND AND OBJECTIVES: Dual blood supply to the anterior interventricular septum (IVS), derived from the septal branches of the left anterior descending artery (LAD) and the conal branch of the right coronary artery (RCA), may prevent ST segment elevation in lead V1 during an anterior acute myocardial infarction (AMI), and predict a favorable in-hospital clinical course. SUBJECTS AND METHODS: The admission 12-lead electrocardiogram (ECG), and the coronary angiograms performed within 10 days of hospital admission, were evaluated in 67 patients with anterior wall AMI, as defined by a ST segment elevation > or =2mm in at least 2 of the V1 to 4 leads. The patients were divided into two groups according to the magnitude of the ST segment elevation in V1 lead: group 1 (ST or =1.5 mm, n=45). The conal branch types were classified into small (a diameter 0.5 mm), reaching the IVS. RESULTS: A large conal branch was found in 11 patients of each group 50 and 24%, respectively (p=0.04). There was no significant relation between the sites of the LAD lesion, whether proximal or distal to the first septal branch, and the presence of ST segment elevation in lead V1. The serum cardiac enzymes, Killip class and the incidence of in-hospital congestive heart failure, were not significantly different. CONCLUSION: The absence of ST segment elevation in lead V1 during an anterior AMI suggested that the IVS is protected by a large conal branch, in addition to the septal branch of the LAD, but this did not influence the in-hospital clinical course.