Background—Although proximal right coronary artery (RCA) occlusion is the culprit commonly responsible for acute right ventricular (RV) infarction (RVI), the severity of RV dysfunction ranges broadly. This study was designed to delineate the patterns of coronary compromise that determine the magnitude of RV ischemic dysfunction.

Methods and Results—In 125 patients with acute inferior myocardial infarction undergoing emergency angiography, the culprit infarct lesion was identified, RV branch flow assessed (TIMI flows and frame counts), and individual patient RV perfusion indices calculated by separately averaging the branch flows and frame counts, which were correlated with RV wall motion by ultrasound. RVI occurred in 53 (42%) patients, with the RCA as the culprit vessel and the lesion sufficiently proximal to compromise flow in at least one RV branch in all cases, thereby resulting in depressed RV perfusion (flow index, 0.7±0.2). In patients without RVI, the RCA was the culprit in 89%; the circumflex, in 11%. RCA culprits were proximal in 19% of such cases, with lack of RVI explained by preserved RV perfusion (flow index, 2.7±0.3; P=0.001) attributable to at least 1 patent RV branch, spontaneous reperfusion, or prominent collaterals. Overall, there was a strong correlation between RV perfusion and wall motion (Spearman correlation coefficient=0.79).

Conclusions—Proximal RCA occlusion compromising RV branch perfusion commonly results in RV ischemic dysfunction. In some cases with proximal RCA culprits, collaterals or spontaneous reperfusion preserve RV performance.