Long‐term observation of fibrillation cycle length in patients under angiotensin II receptor blocker therapy for chronic atrial fibrillation

Introduction The long‐term effect of angiotensin II receptor blockers (ARBs) on atrial fibrillation (AF) is unclear. In this study, we evaluated the change in the fibrillation cycle length (FCL) in patients under long‐term ARB therapy for chronic AF. Methods and results The study population consisted of 25 chronic AF patients who were prescribed the same medication for more than 6 years and in whom specific ECG recording for FCL evaluation could be performed before and after the 6‐year observation period. The patients were divided into 2 groups: those with and without ARB (ARB group and non‐ARB group and n =15 and 10, respectively). FCL was calculated by the spectral analysis of the fibrillation waves in the surface ECG. There was no significant difference in the clinical characteristics between the 2 groups. In the ARB group, the mean FCL was prolonged from 154±20 ms to 187±37 ms ( p =0.005), whereas it remained unchanged in the non‐ARB group (150±12 ms vs. 149±10 ms). In the comparison between patients with and those without FCL prolongation (>30 ms; n =6 and 19, respectively), a significant difference was observed only in those prescribed ARBs. Conclusion In cases of chronic AF, FCL might be prolonged under long‐term ARB treatment.