Feasibility and Safety of Atrial Biopsy　- Evidence From 1,000 Cases.

Background: Atrial biopsy is technically challenging owing to the atria's thin walls and relatively thick endocardium. This study assessed the feasibility and safety of echocardiography-guided atrial biopsy in a consecutive cohort of 1,000 patients who underwent catheter ablation for atrial tachyarrhythmias or percutaneous left atrial (LA) appendage occlusion. Methods and Results: Atrial biopsy was performed at the limbus of the fossa ovalis through the femoral vein using a 5.5-Fr (n=233) or a 7.0-Fr (n=767) bioptome under intracardiac (n=963) or transesophageal (n=37) echocardiography guidance, alongside fluoroscopy. For histological analysis, 5 tissue samples were collected from the same site. Biopsy was successfully completed in 996 (99.6%) patients. Patients were divided based on histological depth into Group A (biopsy beyond the endocardium; n=885) and Group B (endocardial-only biopsy; n=111). Multivariable logistic regression identified larger LA volume, use of a 5.5-Fr bioptome, and amyloid deposition as independent predictors of Group B (P=0.009, P<0.001, and P=0.001, respectively). Moreover, biopsy-related complications were unrecorded. Conclusions: Echocardiography-guided atrial biopsy is a feasible and safe technique. However, atrial enlargement, smaller bioptome size, and amyloid deposition are associated with unsuccessful endocardial penetration and collection of myocardial tissue.