Posterior wall involvement attenuates predictive value of ST-segment elevation in lead V4R for right ventricular involvement in inferior acute myocardial infarction

Abstract

ST-segment elevation of ≥1.0 mm in the right precordial chest lead V4R (ST↑V4R) has been shown to be a reliable marker of right ventricular involvement (RVI) in inferior acute myocardial infarction (IMI). However, the impact of left ventricular posterior wall involvement (PWI) on the relation between ST↑V4R and RVI is unknown. We studied 267 patients with recanalized IMI due to the right coronary artery (RCA) occlusion within 6h after symptom onset. A 12-lead electrocardiogram, lead V4R, and leads V7-9 were recorded on admission. RVI was defined as occlusion proximal to the first major right ventricular branch of the RCA. The perfusion territory of the RCA was assessed by angiographic distribution score, and PWI was defined as a score of ≥0.7. Patients were stratified according to the presence or absence of PWI and RVI. RVI was associated with higher peak creatine kinase and a higher rate of impaired myocardial reperfusion, defined as a myocardial blush grade of 0 or 1 after recanalization, in the presence or absence of PWI, especially the former. RVI was associated with a higher rate of ST↑V4R in the absence, but not in the presence, of PWI. ST↑V4R identified RVI with sensitivities of 34% and 96% (p<0.001), and specificities of 83% and 82% (NS) in the presence and absence of PWI, respectively. In patients with recanalized IMI, RVI is associated with larger infarction and impaired myocardial reperfusion in the presence or absence of PWI, especially the former. However, the presence of PWI attenuates the predictive value of ST↑V4R for RVI.