P-wave indices predict efficacy outcomes in long-term flecainide treated patients with atrial fibrillation

Background/introduction
Flecainide is a commonly used efficient antiarrhythmic drug against atrial fibrillation (AF). P-wave indices reflect the atrial substrate and can predict incident AF, but their role as predictors of treatment outcomes for flecainide-treated AF patients are unknown.

Purpose
To assess if P-wave indices can predict efficacy outcomes in long-term flecainide treated AF patients.

Methods
Consecutive patients admitted for in-hospital flecainide initiation over a 5-year period were retrospectively included. Patient characteristics and baseline ECGs were collected (processed by the 12SL algorithm or manually measured). Echocardiographic measurements were collected up to 1.5 years before baseline. The study outcome was discontinuation of therapy due inadequate rhythm control (IRC). Cox regression analysis was adjusted for age, sex and left atrial volume index (LAVI).

Results
Sixty-seven patients in sinus rhythm were included and followed up for a median of 1.5 years (mean age 59 ± 13 years, 36% females, AF history duration median of 3.0 years, 56% had ≤34 ml left atrial volume index (LAVI) and 9% had a history of persistent AF). At end of follow up twenty patients (30%) had discontinued flecainide treatment; of these seven patients (11%) had discontinued due to IRC. P-wave duration ≥130 ms (HR = 8.4, 95% CI 1.5–46), peak negative P-wave amplitude in V1 ≤ -100 μV (HR = 10, 95% CI 2.0–50) were significantly associated with discontinuation due to IRC in the univariate analysis. However, after adjusted analysis only peak negative P-wave amplitude in V1 ≤ -100 μV (HRadj = 28.7, 95% CI 3.13–263) remained significant.

Conclusion
Peak negative P-wave amplitude in V1 ≤ -100 μV was a risk factor for discontinuation due to inadequate rhythm control in long-term flecainide treated AF patients.