Abstract 13784: Impact of the Variation of Aortomitral Positional Anatomy for the Atrioventricular Conduction Disorder in the Mitral Valve Surgery

Introduction: Advances in cardiac imaging have provided detailed anatomical information, including the variation of the aortic root rotation. This variation affected the distance between membranous septum and right fibrous trigone, that might be synonymous with variation of the conduction system location. However, clinical significance has been unknown. We aimed to analyze the variation of the aorto-mitral position and its relationship of conduction disorder in the mitral valve surgery. Methods: This study included 180 patients underwent simple mitral valve surgery (valve repair: n=159, replacement: n=21). The anatomical variations were classified by preoperative three-dimensional transesophageal echocardiography (3D-TEE), and postoperative occurrence of new conduction disorder was analyzed. Results: As in the image, the variations in the aorto-mitral position were classified into Lateral (14%) or Center appearance (86%) groups, which was further classified to Center (83%), Lateral (14%), or Medial rotation (3%) groups. Atrioventricular conduction disorder was observed as first-degree block (n=24 (13%)) including complete right bundle branch block (n=1 (0.6%)). This disorder newly occurred more in the Lateral appearance compared to the Center (36% vs 10%, p=0.0003). The prolongation of the PR interval (msec) between the pre and postoperative period (ΔPR) was greater in the Lateral appearance than the Center (+17 vs +14, p=0.02). Regarding the aortic root rotation, the conduction disorder occurred in 6%, 27% and 20% patients, and each ΔPR was +2, +16 and +22 of the Center , Lateral , and Medial rotation respectively. Conduction disorder occurred more in the Lateral rotation than the Center (p=0.0017), persisting one year after the surgery (19% vs 2%, p=0.0059). Conclusion: The variation of the aorto-mitral position could be classified by 3D-TEE. The Lateral rotation would be a risk of atrioventricular conduction disorder in the mitral valve surgery.