Elevated brain natriuretic peptide level in patients undergoing atrial fibrillation ablation: is it a predictor of failed ablation or a mere function of atrial rhythm and rate at a point in time?

Background: Pre- and postablation atrial fibrillation (AF) brain natriuretic peptide (BNP) levels were shown to predict increased recurrence of AF following ablation.
Objective: Our objective was to assess whether elevated BNP levels merely represent the presence of AF at the time of measurement or indeed the true recurrence of AF.
Methods and Results: In a prospective study of 88 patients undergoing AF ablation, BNP levels were measured immediately before, after, 24 h, and 4-6 months postablation. BNP levels were stratified by presenting rhythm and ventricular rate at the time of measurement. Median BNP level preablation was higher in patients presenting in AF compared to sinus rhythm (SR) (54(44-79) pg/ml vs. 30(18-47) pg/ml, p < 0.001). Postablation restoration of SR in patients presenting in AF reduced median BNP levels from 54(44-79) pg/ml to 40(37-51) pg/ml, (p < 0.001). However, no change was noted in patients who presented in and maintained SR throughout the procedure (30(18-47) pg/ml to 27(16-40) pg/ml, p = 0.270). At 4-6 months, BNP measured in patients in SR was not significantly different from postablation BNP (35(22-53) pg/ml vs. 38(20-52) pg/ml, p = 0.656), although 35% of them had AF recurrence in 1-year follow-up. Median BNP level measured in five patients while in atrial arrhythmia was elevated compared to postablation BNP (464(421-464) pg/ml to 37(36-37) pg/ml, p = 0.043). BNP levels and ventricular rates are positively correlated at all times pre- and postablation.
Conclusions: BNP level rises acutely during AF and with rapid ventricular rates. BNP level seems to be a function of atrial rhythm and ventricular rate rather than short- or long-term predictor of AF ablation success.