Atrial amyloidosis identified by biopsy in atrial fibrillation: prevalence and clinical presentation

This study aimed to assess the prevalence of cardiac amyloidosis (CA) in patients with non-valvular atrial fibrillation (AF) and to test the hypothesis that early-stage CA can be identified through atrial biopsy.

Atrial biopsy was performed on 578 patients during AF ablation, with right ventricular (RV) biopsy conducted in 385 patients. The amyloid type was assessed using immunohistochemistry. Patients were classified into groups of atrial biopsy–detected CA (abio-CA) and non-CA, with an additional 58 patients clinically diagnosed with CA comprising the clinical CA group.

Amyloid deposits were identified in atrial samples from 40 patients (7%), including 25 amyloid transthyretin (ATTR) types. Prevalence increased to 20%–40% with advancing age, left ventricular (LV) hypertrophy, and the presence of low-voltage areas in the left atrium. The abio-CA group exhibited a thinner LV posterior wall (11.3 ± 2.2 vs 15.3 ± 4.6 mm, P < .001) compared with the clinical CA group. The abio-CA group displayed a thicker LV posterior wall (11.3 ± 2.2 vs 9.6 ± 1.4 mm, P < .001) and a higher frequency of low-voltage areas defined as <0.5 mV (45% vs 13%, P < .001) compared with the non-CA group. Right ventricular biopsy identified amyloid deposits in 13 patients (3%), comprising 11 ATTR and 2 light-chain types. Among the 26 patients in the abio-CA group who underwent RV biopsy, 13 had no amyloid deposits in RV samples, indicating confined atrial amyloidosis.

Atrial biopsy revealed amyloid deposits in 7% of patients undergoing AF ablation, identifying early-stage CA.