Predicting the Efficacy of Antiarrhythmic Agents for Interrupting Persistent Atrial Fibrillation According to Spectral Analysis of the Fibrillation Waves on the Surface ECG

BACKGROUND: Spectral analysis of the fibrillation waves was performed in patients with persistent atrial fibrillation (PAF) to clarify the usefulness of this method of predicting the efficacy of antiarrhythmic agents. METHODS AND RESULTS: The 59 patients with PAF were randomly assigned to pilsicainide (150 mg/day) or bepridil (200 mg/day) therapy for 4 weeks under optimal anticoagulation therapy. When the first therapy did not interrupt PAF, the drugs were changed in a cross-over manner. The fibrillation cycle length (FCL) was calculated using spectral analysis of the fibrillation waves on the body-surface ECG every 2 weeks. Pilsicainide and bepridil were effective in 19 and 20 patients, respectively. The FCL at the basic state was longest in the pilsicainide-effective group, moderate in the bepridil-effective group and shortest in the failure group (P<0.05). The change in FCL with drug administration (DeltaFCL) was larger in the effective than in the ineffective cases (P<0.01). Successful interruption of the atrial fibrillation (AF) with pilsicainide could be expected for patients with a FCL >148 ms (sensitivity =0.917, specificity =0.612, P=0.007) and DeltaFCL >41 ms (sensitivity =0.875, specificity =0.833, P=0.001). CONCLUSIONS: The FCL reflects the electrophysiological properties of the AF substrate and is considered useful for predicting the efficacy of antiarrhythmic agents.