Background:
The arterial supply to the sinoatrial (SA) node shows marked anatomical variability, but its determinants and potential association with coronary atherosclerosis remain unclear. This study aimed to assess the prevalence and anatomical characteristics of large SA arteries (>1.5 mm) on coronary CT angiography (CCTA) and to explore their relationship with coronary calcification.
Methods:
We retrospectively analyzed 600 consecutive patients who underwent CCTA between April 2024 and November 2024. The origin, number of branches, and maximal diameter of the SA artery were assessed. Coronary dominance (right/left/co-dominant) and clinical variables were recorded. Coronary calcium scoring (Agatston score) was performed using a semiautomatic software (syngo.CT CaScoring, Siemens Healthineers) and validated by an experienced observer.
Results:
The mean age of the cohort was 61 ± 10 years; 57 % were male, and the median BMI was 27 kg/m² (IQR 24–30). Right coronary dominance was present in 88 %, left dominance in 8 %, and co-dominance in 4 %. The SA artery most commonly originated from the proximal right coronary artery (segment 1, 54 %) or proximal left circumflex coronary artery (segment 11, 16 %). The remaining SA arteries most frequently originated from the mid RCA (9%, segment 2), and in 13% of cases two SA arteries arose from segment 1 and segment 11. In cases with right coronary dominance, the SA artery originated from the RCA in 63%, from the RCX in 19%, and from both the RCA and RCX in 16%, with no significant correlation between dominance and SA artery origin (r = 0.014, p = 0.726). In co-dominant circulation, the SA artery arose from the RCA in 50%, from both the RCA and left coronary artery in 42%, and from the RCX in 8%, showing a weak but statistically significant correlation between co-dominant supply and the SA origin from the RCA and the left coronary artery (r = 0.133, p = 0.01).The median total Agatston score was 26 (IQR 0–162); the Agatston score per vessel were 0 (0–0.6) for the LM, 12.8 (0–98.9) for LAD, 0 (0–8.9) for RCX, and 0 (0–23.9) for RCA. The median number of identifiable SA arteries was 1 (IQR 1–1), both in the overall cohort and among patients with large SA arteries. A total of 365 (60.8 %) SA branches measured > 1.5 mm (median BMI 27 kg/m² (IQR 24-30), 68% male). In this subgroup, right dominance was most frequent (62 %), and most SA arteries originated from the RCA (67 %) or RCX (14 %). Patients with SA arteries > 1.5 mm had significantly higher total Agatston scores compared with those with SA arteries < 1.5 mm (38.7 [0–234.3] vs. 8.8 [0–116.5]; p = 0.001). This difference was consistent across regional scores for the LAD (23.9 [0–113.2] vs. 1.5 [0–86.8]; p < 0.001), RCX (0 [0–13.7] vs. 0 [0–4]; p = 0.015), and RCA (0 [0–36.9] vs. 0 [0–11.9]; p = 0.006).
Conclusion:
Sinoatrial nodal artery anatomy, including its origin from the right or left coronary artery, is not determined by coronary dominance. Large sinoatrial arteries (> 1.5 mm) are common, predominantly arise from the RCA in right-dominant systems, and are associated with higher coronary atherosclerotic burden.
