Objective: Sinoatrial node (SAN) artery originates from proximal segment of right coronary artery (RCA) or from left circumflex artery. Sinoatrial node artery artery originating from posterolateral (PL) branch of RCA is very rare. Only several cases have been reported. The study was performed to seek the frequency of this variation, evaluate clinical relevance, and describe electrocardiographic, angiographic characteristics of patients.
Methods: Consecutive 1500 coronary angiography were screened to detect specifically SAN artery originating from PL branch of RCA. Patients with this variation were followed-up for one year regarding the arrhythmic events.
Results: The origin of SAN artery was proximal RCA in 1280 (85%), circumflex artery in 208 (14%), and PL branch of RCA in 12 (0.8%) patients (8 male, 4 female, mean age 64+/- 9 years). There was no history of arrhythmia in all patients. One patient presented with atrioventricular block. Indications of angiography were stable angina in 5, unstable angina in 5, and acute myocardial infarction in 2 patients. The patient with inferior myocardial infarction due to RCA total occlusion did not develop bradycardia or conduction defect. In four patients (33%) there was another artery originating from proximal RCA, ending at same territory with the variant artery suggesting dual blood supply. During one-year follow-up none of the patients experienced arrhythmic event.
Conclusions: Sinoatrial node artery originating from distal RCA is very rare. This variation, even in patients with severe RCA disease is not associated with severe arrhythmia. Dual blood supply may be a protective factor in this subgroup of patients from arrhythmic events. To be aware of the origin and course of variant SAN artery may provide safe approach to interventional cardiologist and cardiac surgeon during percutaneous and surgical coronary and atrial interventions.