Presence of sigma shaped right coronary artery is an indicator of poor prognosis in patients with inferior myocardial infarction treated with primary percutaneous coronary intervention

Abstract

The effectiveness of primary percutaneous coronary intervention (PCI) in ST segment elevation myocardial infarction (STEMI) is well established. The clinical variables associated with poor prognosis in patients with STEMI have been extensively investigated. Right coronary artery (RCA) has two anatomical variations detected on coronary angiography namely C-shaped and sigma shaped RCA. The clinical importance of the shape of RCA in patients with STEMI has not been investigated before. To investigate the prognostic value of RCA shape in patients with inferior STEMI treated with primary PCI. Angiographic data of patients with inferior STEMI who were treated with primary PCI were retrospectively recruited. The differentiation of sigma and C-shaped RCAs was shown using single-frame angiograms, obtained during end-diastole of cardiac cycle in the left anterior oblique projection at 25° to 35° with no cranio-caudal angulation. Cardiovascular events at 30-days and on follow up were obtained through review of hospital records and telephone contact with the patient or the patient's relatives. Patients with C-shaped RCAs served as the control group. A total number of 824 patients with inferior STEMI who were treated with primary PCI for RCA were included. Sigma shaped RCA was observed in 15.1% of the subjects. In the sigma shaped RCA group, the door-to-balloon times were longer (32.5 ± 5.1 vs. 27.8 ± 4.6 min; P = 0.01) and TIMI 3 flow restoration rates were lower (76.8% vs. 94.1%; p=0.01) compared to the controls. Mean SYNTAX scores were significantly higher in patients with sigma shaped RCA. Four patients (3.2%) in the sigma shaped RCA group and 23 patients (3.3%) in the control group died by day 30. The incidence of stent thrombosis, recurrent MI, and target lesion revascularization, were similar between the groups. During the follow-up (mean 37.6 ± 13.4 months) 15 patients (12.3%) from the sigma shaped RCA group and 28 (4.1%) patients from the control group died (P = 0.01). The incidence of recurrent MI (27.2% vs. 13.7%; P = 0.01) and major adverse cardiovascular events (29.7% vs. 16.3%; P = 0.01) were significantly higher in the sigma shaped RCA group. In multivariate analysis, age, Killip class of >1, the presence of sigma shaped RCA, post PCI TIMI flow <3 and decreased left ventricular ejection fraction were the independent predictors of long term mortality. Presence of sigma shaped RCA is associated with more severe form of coronary artery disease and worse clinical outcome in patients with inferior STEMI.