Comparison of clinical outcomes between proximal and non-proximal right coronary artery occlusion in patients with inferior ST-segment elevation myocardial infarction.

Background: The clinical outcomes of ST-segment elevation myocardial infarction (STEMI) due to the occlusion of left coronary artery are worse in patients with proximal occlusion than in those with non-proximal occlusion. However, there are few reports that focus on the comparison of clinical outcomes in patients with STEMI between proximal and non-proximal right coronary artery (RCA) occlusions.

Methods: We included 356 patients with STEMI whose infarct-related artery is RCA and divided them into the proximal group (n = 129) and the non-proximal group (n = 227). We defined segment 1 of RCA as proximal, and segments 2, 3, and 4 as non-proximal according to the reporting system of the American Heart Association. The primary endpoint was major cardiovascular events (MACE), which was defined as the composite of all-cause death, non-fatal myocardial infarction, readmission for heart failure, and ischemia-driven target vessel revascularization.

Results: Incidence of shock at admission, requirement for catecholamine during percutaneous coronary intervention (PCI), or mechanical support during PCI tended to be higher in the proximal group (42.6 %) than in the non-proximal group (33.5 %) (p = 0.088). Although the incidence of right ventricular infarction tended to be higher in the proximal group (17.8 %) than in the non-proximal group (10.6 %) without reaching statistical significance (p = 0.072), the incidence of in-hospital death was similar between the 2 groups (1.6 % versus 1.8 %, p = 1.000). The MACE-free survival curves were not different between the 2 groups (p = 0.400). Multivariate Cox hazard analysis revealed that proximal RCA occlusion was not associated with MACE (HR 1.095, 95%CI 0.691-1.737, p = 0.699).

Conclusions: Although the acute phase conditions such as shock or right ventricular infarction tended to be more severe in patients with proximal occlusion, overall clinical outcomes including long-term outcomes were comparable between the proximal and distal RCA occlusions. Furthermore, multivariate analysis showed that the proximal RCA occlusion was not associated with MACE after hospital discharge.