Importance of the conal branch of the right coronary artery in patients with acute anterior wall myocardial infarction: Electrocardiographic and angiographic correlation

Objectives. This study assessed prospectively the correlation between the conal branch of the right coronary artery and the pattern of ST segment elevation in leads V-1 and V(3)R during anterior wall acute myocardial infarction (AMI). Background. The traditional electrocardiographic (ECG) definition of anteroseptal AMI-ST segment elevation in leads V-1 to V-3-has recently been challenged, The significance of ST segment elevation in lead V-1 during anterior wall AMI is unclear. Methods. The admission 12-lead ECG with additional lead V(3)R and the coronary angiograms performed within 10 days of hospital admission were evaluated in 28 consecutive patients (mean age +/- SD 62 +/- 9 years) admitted to the coronary care unit with anterior wall AMI, Patients were classified into two groups according to the magnitude of ST segment elevation in lead V-1: group A (elevation greater than or equal to 1.5 mm, n = 12) and group B (elevation <1.5 mm, n = 16). Two types of conal branch mere identified: small (not reaching the interventricular septum [IVS]) and large (reaching the IVS). Results. ST segment elevation in lead V(3)R was found in 11 (92%) and 6 (37%) patients from group A and group B, respectively (p < 0.001); a small conal branch was seen in 10 (83%) and 3 (19%) patients, respectively (p < 0.001), Ten patients (all from group B) had a large conal branch. Conclusions. ST segment elevation in lead V-1 in the admission ECG of patients with anterior wall AMI is strongly related to ST segment elevation in lead V(3)R and is associated with a small conal branch, Our findings suggest that lead V-1 reflects the right paraseptal area supplied by the septal branches of the left anterior descending coronary artery (LAD), alone or together with the conal branch. The absence of ST segment elevation in lead V-1 during anterior AMI suggests that the IVS is protected by a large conal branch in addition to the septal branches of the LAD (double circulation). (C) 1997 by the American College of Cardiology.