Value of lead V 4R for recognition of the infarct coronary artery in acute inferior myocardial infarction

Abstract

In 84 patients with an acute inferior wall myocardial infarction (MI) admitted within 10 hours after the onset of chest pain, a right precordial lead V 4R electrocardiogram was recorded in addition to the standard 12-lead electrocardiogram. The presence or absence of ST-segment elevation in lead V 4R was correlated with results of coronary angiography performed 2 to 26 weeks (mean 10) after MI. Patients were classified into 3 groups: (1) those with a critical stenosis or occlusion proximal to the first right ventricular (RV) branch (27 patients); (2) those with stenosis distal to the right ventricular branch of the right coronary artery (36 patients); and (3) those with stenosis in the left circumflex coronary artery (21 patients). The presence of ST-segment elevation ≥ 1 mm in lead V 4R has a sensitivity of 100% and a specificity of 87% for occlusion of the right coronary artery above the first RV branch; the predictive accuracy is 92%. Seven of 36 patients with a distal occlusion of the right coronary artery showed ST-segment elevation of 1 mm or more in lead V 4R. The absence of ST-segment elevation ≥ 1 mm in lead V 4R excluded proximal occlusion of the right coronary artery. ST-segment elevation in lead V 4R was not seen either in 29 of 36 patients with a distal occlusion of the right coronary artery or in all patients with an occlusion of the left circumflex artery. Recording of lead V 4R within 10 hours after onset of acute inferior wall MI can give information rapidly about the vessel responsible for MI. This could have implications when emergency procedures (streptokinase infusion, balloon dilatation and emergency surgery) are considered.