Long-term outcome after cardioversion of atrial fibrillation: Prediction of recurrence with P wave signal averaged ECG and chemoreflexsensitivity

Abstract

Aim The recurrence of atrial fibrillation after cardioversion was a general problem in medical practice. Methods We wanted to test the hypothesis that the recurrence of atrial fibrillation could be predicted by measurements of P wave triggered P wave signal averaged ECG and chemoreflexsensitivity (CHRS) in 118 consecutive patients one day after successful electrical cardioversion. We measured the filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20) with P wave triggered P wave signal averaged ECG. The CHRS was calculated of a ratio between the difference of RR intervals in ECG and venous pO 2 before and after 5-min oxygen inhalation. The pathologic CHRS was predefined as a CHRS below 3.0 ms/mm Hg. Results A recurrence of atrial fibrillation was observed in 57 patients (48%) during a 9.3-month follow-up. The left atrial size (41.9 ± 4.0 vs. 39.3 ± 3.1 mm, P < 0.0003) was larger, the FPD (139.6 ± 16.0 vs. 118.2 ± 14.1 ms, P < 0.0001) was longer, the RMS 20 (2.57 ± 0.77 vs. 3.90 ± 0.99 μV, P < 0.0001) and the CHRS (2.66 ± 1.18 vs. 4.01 ± 1.66 ms/mm Hg, P < 0.0001) were lower in patients with recurrence of atrial fibrillation. A cut-off point was defined with FPD ≥ 126 ms and RMS 20 ≤ 3.1 μV and could predict atrial fibrillation with a specificity of 77%, a sensitivity of 72%, a positive value of 75%, a negative predictive value of 75% and an accuracy of 75%. Patients with FPD ≥ 126 ms and RMS 20 ≤ 3.1 μV had nearly a 7-fold increase risk for recurrence of atrial fibrillation. Conclusion The recurrence of atrial fibrillation after cardioversion could be detected by P wave signal averaged ECG and an analysis of CHRS. These methods seem to be appropriate to show a delayed atrial conduction and a neurovegetative imbalance which might be possible trigger mechanisms of reinitiating of atrial fibrillation.