Copyright © 2015 BMJ Publishing Group. We report a case of a patient admitted with an acute ST elevation myocardial infarction following occlusion of his right coronary artery, successfully treated with thrombectomy and percutaneous coronary intervention (PCI). Coronary angiography and multislice CT revealed a single right coronary artery with two anomalous branches (constituting the left coronary system); one branch passed between the pulmonary trunk and the aorta before dividing into three separate branches, while the other anomalous branch passed anterior to the pulmonary trunk, consistent with a Yamanaka R-IIIC classification. The course of this Yamanaka R-IIIC subtype is unusual as both anomalous branches combine to form a dual origin left anterior descending artery. The course of these anomalous branches places the patient at an increased risk of future myocardial ischaemia, infarction and sudden cardiac death. As symptoms typically develop on exertion, this cohort may benefit from exercise myocardial perfusion imaging to identify high-risk patients.