Clinical anatomy of the right intercostal arteries: Another neighbor to know before pulmonary vein isolation.

Background: Hemothorax caused by a right intercostal artery (ICA) injury behind the left atrium (LA) is a potentially fatal complication during pulmonary vein isolation. However, their anatomical relationship has not been fully elucidated.

Objective: This study aimed to investigate the clinical anatomy of the right ICA in relation to the LA.

Methods: This retrospective study included 100 patients (70.2 ± 10.6 years, 39.0% female) who underwent cardiac computed tomography. The patients were divided into sinus rhythm (SR) and atrial fibrillation (AF) groups. We focused on the distance between the LA and right ICAs and its predictive factors.

Results: On average, 3.7 ± 0.7 right ICAs were found behind the LA. Among these, the eighth ICA was the closest in 54% of the cases, followed by the seventh ICA in 29%, and the ninth ICA in 14%. The average closest distance between them was 3.8 ± 3.8 mm, which was significantly shorter in the AF group than in the SR group (3.0 ± 3.2 mm vs. 4.7 ± 4.2 mm, p = 0.006). Multivariate analysis revealed that a thinner chest cavity (β = -0.512, p = 0.002) and LA dilatation (β = -0.432, p = 0.001) were predictors of shorter distance. The closest points distributed along the vertebral column, generally near the inferior pulmonary vein orifices.

Conclusions: Right ICA-LA proximity was systematically clarified. Particularly in cases with an enlarged LA and/or thin chest cavity, operators should be aware of the potential risk of injuring the right ICA during pulmonary vein isolation.