Low-Dose Ibutilide Combined with Catheter Ablation of Persistent Atrial Fibrillation: Procedural Impact and Clinical Outcome

Analysis of the success rate of conversion using ibutilide administration in radiofrequency catheter ablation of persistent atrial fibrillation and its effects on postoperative recurrence

OBJECTIVE

To assess the efficacy of ibutilide administration during radiofrequency catheter ablation of persistent atrial fibrillation (AF), to explore the success rate of conversion and related influential factors, and to analyze the effects of ibutilide on postoperative recurrence.

METHODS

A total of 192 patients with persistent AF who underwent catheter ablation from January 1, 2019, to December 31, 2021. These patients failed in conversion of AF to normal sinus rhythm by intraoperative catheter ablation. Patients were categorized into effective group (115 cases) and ineffective group (77 cases) based on whether sinus rhythm was restored after application of ibutilide.

RESULTS

The overall success rate of conversion using ibutilide administration was 59.9%. The success rate was associated with weight ((68.12 ± 11.72 vs. 72.83 ± 12.08) kg, P = 0.008), the duration of AF ((34.67 ± 55.68 vs. 66.52 ± 95.21) months, p = 0.008), diameter of left atrium (LAD) ((44.39 ± 5.80 vs. 47.36 ± 6.10) mm,P = 0.002), and N-terminal pro-brain natriuretic peptide (NT-proBNP) level ((854.85 ± 770.84 vs. 662.88 ± 659.18) pg/ml,P = 0.030). The results showed the duration of AF was associated with early recurrence, while early recurrence was not a risk factor for late recurrence. And duration of AF was associated with postoperative maintenance time of normal sinus rhythm, whereas successful conversion into normal sinus rhythm using ibutilide administration had no influence on postoperative maintenance time of normal sinus rhythm.

CONCLUSION

Ibutilide showed to be effective in catheter ablation of AF, the success rate of conversion was correlated with the duration of AF, LA diameter, and NT-proBNP level. Besides, the duration of AF was found as a risk factor for early postoperative recurrence, while ibutilide administration for successful conversion had no influence on predicting postoperative recurrence and had no influence on postoperative maintenance time of sinus rhythm.

Low-Voltage Zones as the Atrial Fibrillation Substrates: Relationship With Initiation, Perpetuation, and Termination

Background: Low-voltage zones (LVZs) were usually targeted for ablation in atrial fibrillation (AF). However, its relationship with AF initiation, perpetuation, and termination remains to be studied. This study aimed to explore such relationships.

Methods: A total of 126 consecutive AF patients were enrolled, including 71 patients for AF induction protocol and 55 patients for AF termination protocol. Inducible and sustainable AF were defined as induced AF lasting over 30 and 300 s, respectively. Terminable AF was defined as those that could be terminated into sinus rhythm within 1 h after ibutilide administration. Voltage mapping was performed in sinus rhythm for all patients. LVZ was quantified as the percentage of the LVZ area (LVZ%) to the left atrium surface area.

Results: The rates of inducible, sustainable, and terminable AF were 29.6, 18.3, and 38.2%, respectively. Inducible AF patients had no significant difference in overall LVZ% compared with uninducible AF patients (10.2 ± 11.8 vs. 8.5 ± 12.6, p = 0.606), while sustainable and interminable AF patients had larger overall LVZ% than unsustainable (16.2 ± 11.5 vs. 0.5 ± 0.7, p < 0.001) and terminable AF patients (44.6 ± 26.4 vs. 26.3 ± 22.3, p < 0.05), respectively. The segmental LVZ distribution pattern was diverse in the different stages of AF. Segmental LVZ% difference was initially observed in the anterior wall for patients with inducible AF, and the septum was further affected in those with sustainable AF, and the roof, posterior wall, and floor were finally affected in those with interminable AF.

Conclusions: The associations between LVZ with AF initiation, perpetuation, and termination were different depending on its size and distribution.

Identification of circumferential pulmonary vein isolation responders among patients with persistent atrial fibrillation: clinical value of the sequential low-dose ibutilide test

AIMS

Circumferential pulmonary vein isolation can be effective as sole treatment for persistent atrial fibrillation. However, identifying those patients who will respond to this therapy remains a challenge. We investigated the clinical value of the sequential low-dose ibutilide test for identifying patients with persistent atrial fibrillation in whom pulmonary vein isolation is effective as sole therapy.

METHODS AND RESULTS

In a prospective cohort of 180 consecutive patients with persistent atrial fibrillation, intravenous low-dose (0.004 mg/kg) ibutilide was administered 3 days before ablation and after the completion of circumferential pulmonary vein isolation. In patients in whom ibutilide did not terminate atrial fibrillation pre-procedurally, but successfully terminated it intraprocedurally, no further atrial substrate modification was performed. Pre-procedural low-dose ibutilide failed to terminate the arrhythmia in all patients with persistent atrial fibrillation, while pulmonary vein isolation ± low-dose ibutilide terminated persistent atrial fibrillation in 55 (30.6%) of them (PsAF group 1). The remaining 125 (69.4%) patients underwent electrogram-based ablation (PsAF Group 2). The control group comprised 379 consecutive patients with paroxysmal atrial fibrillation who underwent pulmonary vein isolation over the same period. At 24 months follow-up, 39 (70.9%) patients in PsAF Group 1 and 276 (72.8%) patients in the control group were free from atrial tachyarrhythmias (P = NS); the arrhythmia-free rates in both groups were higher than that in PsAF group 2 (58.4%, P = 0.005).

CONCLUSION

The sequential low-dose ibutilide test is a simple method for identifying patients with persistent atrial fibrillation in whom pulmonary vein isolation alone is an appropriate treatment strategy.