Abstract 4103: The Effects of Angiotensin II Receptor Blockade on Atrial Late Potential in Paroxysmal Atrial Fibrillation Patients with Hypertension
P-wave signal-averaged ECG (P-SAE) has been used to characterize atrial conduction delay, which is atrial late potential. In previous study, we have demonstrated that P-SAE is useful for detection of patients with symptomatic paroxysmal atrial fibrillation (AF) and prediction of transition to chronic AF in patients with paroxysmal AF. Several studies have shown that atrial late potential is highly related to atrial fibrosis, and that angiotensin II receptor blockade (ARB) might inhibit the development of atrial fibrosis. The purpose of this study is to investigate the effects of ARB on atrial late potential in paroxysmal AF patients with hypertension. ARBs (Olmesartan or Candesartan) were administered to 26 outpatients with clinically diagnosed paroxysmal AF and hypertension for three months. Before and after ARB administration, P-SAE was recorded. Total P-wave duration (Ad) and root mean square voltage for the last 20ms of filtered P-wave (Lp20) were measured. Lp20/Ad was calculated as an index of atrial late potential. Ad showed a significant decrease (145±17→138±14ms: p<0.001) and Lp20 showed a tendency to increase (2.4±0.9→2.8±1.0 μV). Lp/Ad increased significantly (0.017±0.009→0.021±0.009μV/ms: p<0.001). These results strongly suggested that ARBs might reduce the arrhythmic substrate for AF by the reverse remodeling based on inhibition of atrial fibrosis, consequently the improvement of atrial late potential.