Clinical Utility of Intravenous Nifekalant Injection during Radiofrequency catheter Ablation for Persistent Atrial Fibrillation

Abstract

Background: Radiofrequency catheter ablation (RFCA) for persistent atrial fibrillation (AF) is still challenging even in RFCA-era for AF. The aim of this study was to assess the clinical utility of nifekalant, a pure potassium channel blocker,during RFCA for persistent AF.

Methods and results: We retrospectively enrolled 157 consecutive persistentAF patientsundergoing first RFCA procedure withcomplex fractionated atrial electrogram (CFAE)ablation after pulmonary veins isolation and compared outcomes between patientswith (NFK group: N=79) and without (No-NFK group: N=78)additional CFAE ablation using intravenous nifekalant (0.3mg/kg). Primary endpoint was 24-month atrial arrhythmia-free survival post ablation.The prevalence of AF terminationwas significantly higher in NFK group than No-NFK group (64.6% versus 7.7%, P<0.001). Arrhythmia-free survival, however, was not significantly different between 2 groups (61.5% versus 54.1%, P=0.63).There was no significant difference between 2 groups in the prevalence of recurrent atrial tachycardia(25.0% versus 23.5%, P=0.89). Arrhythmia-free survivalin patients with AF termination during procedure was significantly higher thanthose without (73.0% versus 41.0%, P=0.002; adjusted hazard ratio 0.48, 95% confidence interval 0.17-0.84, P=0.02) amongNFK group,but not amongNo-NFK group (66.7% versus 53.2%, P=0.53).

Conclusions: Intravenous nifekalant injection during additional CFAE ablation did not improve sinus maintenancerate after RFCA procedure for AF, but AF termination by nifekalant injection could be a clinical predictor of better success rates after procedure.

Keywords: Complex Fractionated Atrial Electrogram; Nifekalant; Radiofrequency Catheter Ablation; Spersistentatrial Fibrillation.

Figure 1.. Study population

AF=atrial fibrillation

Figure 2A.. . A representative case of atrial fibrillation termination during procedure in NFK group.A) CARTOTM image with ablation points,A 66-year-old man with long-standing atrial fibrillation and left ventricular dysfunction received radiofrequency catheter ablation. During procedure, we ablated sites of complex fractionated atrial electrogram (CFAE) from mitral annulus to ostium of left atrial appendage (purple points)after pulmonary veins isolation.The electrical excitation of coronary sinus was organized and, then, the cycle length was constantly prolonged by intravenously injected nifekalant (0.3mg/kg)

AP=antero-posterior view, d=distal, CFAE=complex fractionated atrial electrogram, CS=coronary sinus, HRA=high right atrium, p=proximal, RAO=right anterior oblique view

Figure 2B.. A representative case of atrial fibrillation termination during procedure in NFK group.B) intracardiac electrocardiograms Still remained CFAE ablation, furthermore,was continued at left atrial appendage, anterior left atrium and coronary sinus (orange points). When we ablated sites of CFAEs at right atrial septum, atrial fibrillation was converted to sinus rhythm. We added tricuspid valve isthmus ablation and finished procedure. Sinus rhythm has been maintained for 906 days and left ventricular function is recovered.

AP=antero-posterior view, d=distal, CFAE=complex fractionated atrial electrogram, CS=coronary sinus, HRA=high right atrium, p=proximal, RAO=right anterior oblique view

Figure 3.. Recurrent arrhythmia-free survival between NFK group and No-NFK group A) after the first procedure ,and B) after the last procedure

Figure 4A.. Recurrent arrhythmia-free survival after procedure between patients with and without AF termination in NFK group and No-NFK group A),B)after the first procedure

Figure 4B.. Recurrent arrhythmia-free survival after procedure between patients with and without AF termination in NFK group and No-NFK group C),D) after the last procedure