CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 3, May/June 2022 112 AFRICA Response to ibutilide and the long-term outcome after catheter ablation for non-paroxysmal atrial fibrillation Yanfang Wu, Peng Gao, Yongtai Liu, Quan Fang Abstract Purpose: This study aimed to assess the relationship between the cardiac rhythm response to ibutilide infusion after pulmonary vein isolation and the recurrence of long-term atrial arrhythmias. Methods: One hundred and thirty-eight patients with nonparoxysmal atrial fibrillation who had had their first catheter ablation were retrospectively included. All patients whose atrial fibrillation did not terminate after pulmonary vein isolation were administered intravenous ibutilide (1.0 mg). Those with termination of atrial fibrillation after ibutilide administration were defined as responders (n = 86); those without termination of atrial fibrillation, as non-responders (n = 52). The primary endpoint was any documented recurrence of atrial arrhythmia lasting more than 30 seconds after the initial catheter ablation. Results: Conversion of atrial fibrillation to sinus rhythm, directly or via atrial flutter, with ibutilide administration was achieved in 62.3% of patients. A longer duration of atrial fibrillation was associated with failed termination of atrial fibrillation (odds ratio 1.009, 95% confidence interval 1.002–1.017, p = 0.011). During a median follow-up period of 610 days (interquartile range 475–1 106) post ablation, non-responders (n = 24, 46.2%) had a higher recurrence rate of atrial arrhythmia than the responders (n = 26, 30.2%; log-rank, p = 0.011) after the initial catheter ablation. Multivariate Cox regression analysis revealed that non-responders (hazard ratio 1.994, 95% confidence interval 1.117–3.561, p = 0.020) was significantly correlated with recurrence of atrial arrhythmias. Conclusion: In patients whose atrial fibrillation persisted after pulmonary vein isolation, the response to ibutilide administration could predict the recurrence of atrial arrhythmias after catheter ablation, which may be useful for risk stratification for recurrence of atrial fibrillation and individualised management of atrial fibrillation. Keywords: ibutilide, atrial fibrillation, catheter ablation, prognosis Submitted 5/2/21; accepted 13/9/21 Published online 15/10/21 Cardiovasc J Afr 2022; 33: 112–116 www.cvja.co.za DOI: 10.5830/CVJA-2021-044 Atrial fibrillation (AF) is the most common clinical arrhythmia, with a prevalence of 3.0% in persons aged over 21 years.1 Since over 90% of the triggering factors of AF are found in the pulmonary veins (PVs), electrical isolation of the PVs has been the cornerstone of AF ablation.2-4 However, AF termination during or upon completion of pulmonary vein isolation (PVI) occurs in only a minority of patients with persistent AF. During catheter ablation (CA) of persistent AF, antiarrhythmic drug (AAD) administration is a common practice to facilitate the ablation. Ibutilide, which is a class III AAD, can block the rapidly outward delayed rectifier potassium (K+) current to prolong the atrial refractory period, subsequently terminating AF.5 In some previous studies, ibutilide showed a 50.5 to 56% cardioversion rate for AF in patients without ablation.6,7 After PVI completion, the re-entrant wave fronts between the PV and the left atrium are interrupted, which could in turn facilitate a higher AF termination rate after ibutilide administration. However, studies reporting the efficacy of ibutilide in the termination of AF after PVI completion are limited. In patients with non-paroxysmal AF, there was a 31% recurrence rate of AF after catheter ablation, which was associated with a poor prognosis, such as stroke.8 The prediction of AF recurrence could help optimise individualised AF management. The approach employed for AF termination was reported to be associated with AF recurrence after ablation.9 As mentioned, ibutilide can be used for AF termination, while patients with different clinical characteristics had different responses to ibutilide. Currently, studies about intraprocedural ibutilide mostly focus on low-dose application and the difference in ablation strategy may influence the judgement of the effect of ibutilide on the prognosis.10,11 In patients with persistent AF after PVI, it remains to be established whether the heart rhythm response to ibutilide infusion with a standard dose is associated with ablation outcome. The use of ibutilide in non-paroxysmal AF treatment is unknown. This study therefore aimed to assess the relationship between the cardiac rhythm response to ibutilide infusion after PVI and recurrence of long-term atrial arrhythmias (AAs), which may provide a useful tool for prediction of AF recurrence. We hypothesised that AF termination with ibutilide infusion after PVI indicates good rhythm control during a long-term follow up. Methods A total of 193 consecutive patients with non-paroxysmal AF who underwent CA for the first time between January 2014 and December 2018 at our institution were retrospectively included. Patients with valvular heart disease, a history of hyperthyroidism or cardiac surgery, or failed intraprocedural cardioversion were excluded. Of the remaining patients, seven had sinus rhythm (SR) before CA, 11 had AF conversion to SR during or Department of Cardiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China Yanfang Wu, MD Peng Gao, MD Yongtai Liu, MD Quan Fang, MD, dr_cardio@163.com
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