Hypertension is not a predictor of atrial fibrosis in patients with atrial fibrillation - evidence from atrial biopsy

Objective: Hypertension is considered to promote atrial fibrosis and contribute to the development of atrial fibrillation. The purpose of this study is to investigate the effect of arterial hypertension on atrial fibrosis in patients with atrial fibrillation (AF). Design and method: We examined 234 patients (67 ± 12 years old, 72 female genders, 145 non-paroxysmal AF type) who underwent right atrial septum biopsy under the guidance of intracardiac echocardiography and fluoroscopy (Figure A) during catheter ablation for AF. The extent of histological fibrosis (%Fibrosis) was quantified using digital imaging platform based on the Masson trichrome staining (Figure B). Clinical factors possibly associated with %Fibrosis were evaluated using simple and multiple linear regression analysis. Results: A total of 132 patients had hypertension. The mean %fibrosis was 7 ± 4% (range 1–20%). There was no significant difference of %Fibrosis in patients with and without hypertension (Figure C). Univariate analyses identified age, female gender, smaller body surface area (BSA), decreased eGFR, non-paroxysmal AF type, larger left atrial volume/BSA, and higher E/e were associated with increase in %Fibrosis. Multivariate analysis showed that only non-paroxysmal AF type and left atrial volume/BSA were identified as significant clinical factors associated with %Fibrosis (Figure D). Conclusions: Our data suggest that hypertension is not an independent predictor of atrial histological fibrosis in patients with AF. The mechanism of atrial fibrosis would not be directly related to arterial hypertension contrary to previous hypotheses.