Is hypertension a cause of atrial cardiomyopathy in patients with atrial fibrillation? -evidence from atrial biopsy-

Objective: Hypertension is considered to be associated with the development of ventricular cardiomyopathy, however, little is known about its impact on atrial cardiomyopathy. The purpose of this study is to investigate the relationship between hypertension and atrial cardiomyopathy 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 from the limbus of fossa ovalis under the guidance of intracardiac echocardiography during catheter ablation for AF. High-density bipolar voltage mapping was also performed using a grid mapping catheter during high right atrial pacing. Atrial cardiomyopathy was evaluated based on quantitative histological analyses including the extent of fibrosis (%Fibrosis), extent of intercellular space (%Intercellular-space), severity of myofibrillar loss (%Myofibrillar-loss), extent of adipocyte (%Adipocyte), myocyte size, and nuclear density were quantified using a digital image platform based on the Masson Trichrome and Hematoxylin and Eosin staining (Figure A). Mean voltage at the biopsy site and the whole left atrium (LA) was evaluated (Figure B). Univariate analyses were performed on these histological factors between patients with hypertension and those without. Covariate correction for age and gender was also performed. Results: A total of 132 patients had hypertension. Univariate analysis showed no significant difference in %Fibrosis, %Intercellular-space, %Myofibrillar-loss, %Adipocyte, Myocyte size, mean voltage at the biopsy site and of the whole LA, LA volume/body surface area, and LA diameter between patients with and without hypertension. Nuclear density was significantly lower in patients with hypertension than those without hypertension (368 ± 128 vs. 409 ± 151/mm2, p = 0.006) (Figure C). After adjusting for age and gender, there was no significant difference in the nuclear density (p = 0.129). Conclusions: Arterial hypertension is not associated with the severity of atrial cardiomyopathy in patients with AF.