BACKGROUND: The coronary atrial circulation is the network of vessels that supply blood to the atria, originating from the left circumflex and right coronary arteries. Current descriptions of this arterial system are based on anatomical studies with a limited number of patients, predominantly male. In addition, there is a lack of consensus its angiographic nomenclature. AIMS: This study aimed to evaluate the anatomical variations of coronary atrial branches (CAB) and investigate sex-related differences in their distribution. METHODS: Consecutive patients with ST-elevation myocardial infarction who underwent primary PCI at a tertiary center between 2004 and 2013 were included. Angiographic anatomy of all visible CAB on index coronary angiography was systematically evaluated following a stepwise method, including type of branch
coronary artery of origin
segment of origin, branch course, and atrial dominancy. Specific differences between both sexes were analyzed. RESULTS: A total of 998 patients (age 61 ± 12, 79% male) were included. The sinus node artery was the dominant CAB in 916 (93%), originating in 37% from distal coronary segments. Different CAB anatomical patterns were identified in both sexes. Compared to females, males presented a higher prevalence of left-sided CAB (left circumflex CAB 459 [58%] vs. 96 [45%], p <
0.002
sigma-shaped CAB 267 [30%] vs. 39 [21%], p = 0.003) and of a left-balanced atrial circulation pattern-defined as the presence of at least two CAB originating from the LCx, with one of them being the dominant CAB-245 (31%) versus 45 (21%), p = 0.005. CONCLUSIONS: This study provides a systematic approach to the angiographic evaluation of CAB. Sex-related phenotypical differences of CAB distribution were found, with males presenting a higher presence of left-sided CAB and a left-balanced atrial circulation pattern.