Coronary sinus ostium anatomy in patients with atrioventricular nodal and atrioventricular reentrant tachycardia: a cardiac computed tomography study.

BACKGROUND: The coronary sinus (CS) is anatomically related to the atrioventricular node and the slow pathway region and may influence the mechanisms of supraventricular tachycardia. Differences in CS ostium dimensions have been suggested between atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT), but data derived from cardiac computed tomography (CT) are limited. METHODS: In this single-center observational study, patients who underwent successful catheter ablation for AVNRT or AVRT and subsequently had cardiac CT angiography between October 2022 and August 2024 were included. Coronary sinus ostium diameters were measured at the junction with the right atrium using multiplanar reformatted CT images. Anteroposterior and superoinferior diameters were recorded. Continuous variables were compared using the Mann-Whitney U test and categorical variables using the chi-square test. RESULTS: A total of 40 patients were analyzed (29 with AVNRT and 11 with AVRT). Baseline clinical characteristics were similar between groups. Both the anteroposterior and superoinferior diameters of the CS ostium were significantly larger in the AVNRT group compared with the AVRT group (12.1 [10.8-12.7] vs. 10.7 [9.5-11.6] mm, p = 0.041 and 14.6 [13.1-17.1] vs. 13.7 [11.6-14.1] mm, p = 0.029, respectively). CONCLUSIONS: Cardiac CT demonstrated significantly larger coronary sinus ostium dimensions in patients with AVNRT compared with AVRT. These findings support a potential anatomical contribution of the coronary sinus to the arrhythmogenic substrate of AVNRT and may have implications for electrophysiological evaluation and ablation strategies.