Ventricular response as a predictor of the termination of sustained paroxysmal atrial fibrillation

Background: Atrial fibrillation (AF) is the most common sustained atrial arrhythmia. Accurate detection of the timing and possibility of AF termination is vital for optimizing rhythm and rate control strategies. The present study evaluated whether the ventricular response (VR) in AF offers a distinctive electrocardiographic indicator for predicting AF termination. Methods: Patients experiencing sustained paroxysmal AF for more than 3 h were observed using 24-h ambulatory Holter monitoring. VR within 5 min before AF termination (VR _{0–5 min, BAFT}) was compared with VR observed during the 60th to 65th min (VR _{60–65 min, BAFT}) and the 120th to 125th min (VR _{120–125 min, BAFT}) before AF termination. Maximum and minimum VRs were calculated on the basis of the average of the highest and lowest VRs across 10 consecutive heartbeats. Results: Data from 37 episodes of paroxysmal AF revealed that the minimum VR_{0–5 min, BAFT} (64 ± 20 bpm) was significantly faster than both the minimum VR_{120–125 min, BAFT} (56 ± 15 bpm) and the minimum VR_{60–65 min, BAFT} (57 ± 16 bpm, p <.05). Similarly, the maximum VR_{0–5 min, BAFT} (158 ± 49 bpm) was significantly faster than the maximum VR_{120–125 min, BAFT} (148 ± 45 bpm, p <.05). In the daytime, the minimum VR_{0–5 min, BAFT} (66 ± 20 bpm) was significantly faster than both the minimum VR_{60–65 min, BAFT} (58 ± 17 bpm) and minimum VR_{120–125 min, BAFT} (57 ± 15 bpm, p <.05). However, the mean and maximum VR_{0–5 min, BAFT} in the daytime were similar to the mean and maximum VR_{120–125 min} in the daytime, respectively. At night, the minimum, mean, and maximum VR_{0–5 min, BAFT} were similar to the minimum, mean, and maximum VR_{120–125 min}, respectively. Conclusions: Elevated VR rates during AF episodes may be predictors for the termination of AF, especially during the daytime and in patients with nondilated left atria. These findings may guide the development of clinical approaches to rhythm control in AF.