CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 3, May/June 2022 AFRICA 115 The timing for the second procedure was at least 90 days after the initial ablation in patients with AA recurrence. Nineteen of 50 patients (13.8%) with AA recurrence underwent repeat procedures. At the second procedure, 14 patients had a PV–left atrial gap, and the mean number of reconnected PVs was 1.33 ± 0.84 per patient. Of the remaining five patients, one had AF originating from SVC, one had mitral isthmus-dependent AFL, one had left atrial roof-dependent AFL, one had left atrial low-voltage area-associated AF, and one underwent the second procedure at a different medical centre. After the second CA, one ibutilide responder was lost to follow up and 36/137 (26.3%) patients had AA recurrence. The AA recurrence rate after the second CA was higher in non-responders than in responders [36.5 (19/52) vs 20% (17/85), p = 0.033]. Kaplan–Meier analysis showed that the AA-free survival rate after the second CA remained significantly higher in responders than in non-responders (log-rank test, p = 0.010) (Fig. 2B). Discussion The key findings of this study were as follows: (1) in patients with persistent AF after PVI, the rate of AF termination by ibutilide administration was 62.3%; (2) a longer AF duration was associated with failed AF termination by ibutilide infusion; (3) failed AF termination with ibutilide infusion after PVI was associated with an unfavourable arrhythmia-free survival during a long-term follow up. DCC is frequently used for AF termination and achieves SR in more than 85% of patients.12,13 However, DCC is typically performed under intravenous procedural anaesthesia, usually resulting in displacement of the patients. By contrast, ibutilide administration is a much simpler procedure. In patients with persistent AF after PVI completion, ibutilide could prolong the left atrial micro-re-entrant cycle length, which could in turn cause the following fibrillatory wave fronts to enter an effective refractory period and organise the electrical activity, thereby terminating AF. In this study, we found that the rate of AF termination by ibutilide administration was 62.3% after PVI completion in patients with non-paroxysmal AF, which is effective for AF termination. However, in a previous study, only 12 to 26.9% of cases achieved AF termination after ibutilide infusion.11,14 Such discrepancies may be related to the high dose of ibutilide and the high quality of PVI in our study. Nevertheless, 87.2% of the patients in our cohort had direct conversion to SR. Although PVI can reduce the interplay between PV and the left atrium, persistent AF may be maintained by pathological changes in electrical remodelling and/or structural remodelling after PVI completion. In our study, we found that ibutilide had a limited effect on AF termination in patients with a longer AF duration. In a previous study, a longer AF duration also showed a significant influence on failed AF termination by ibutilide in patients with sustained AF without PVI.15 As we know, a longer AF duration contributes to progression of atrial remodelling.16 Patients with a longer AF duration may have severe atrial remodelling; therefore ibutilide may have a worse effect on AF termination. For patients with longer AF duration, DCC may be the first choice due to the arrhythmic effect of ibutilide. The response to ibutilide after PVI may be associated with the extent of atrial remodelling.17 Ibutilide promotes organisation of intracardial electrical activity. Therefore, if AF is terminated and converted to SR or AFL after ibutilide administration, the atrial remodelling may be mild; otherwise, it may be severe. A large anatomical or conductive obstaclebased re-entry may have an excitable gap that cannot be closed by effective refractory period prolongation, and this re-entrant mechanism may be insensitive to ibutilide infusion.18 Therefore, the response to ibutilide administration after PVI may help guide intraprocedural ablation. He et al.14 reported that low-dose ibutilide treatment after PVI could help appropriately select patients with persistent AF who needed to undergo PVI alone. For patients with AF termination after ibutilide administration, PVI is sufficient for rhythm Follow-up duration (days) No. at risk Ibutilide responders 86 68 29 18 10 5 0 Ibutilide non-responders 52 33 14 8 3 1 0 0 365 730 1 095 1 460 1 825 2 190 Survival free from atrial arrhthmias 1.0 0.8 0.6 0.4 0.2 0.0 Log-rank test, p = 0.011 Ibutilide responders Ibutilide non-responders Follow-up duration (days) No. at risk Ibutilide responders 85 69 34 23 13 7 0 Ibutilide non-responders 52 38 17 12 4 1 0 0 365 730 1 095 1 460 1 825 2 190 Survival free from atrial arrhthmias 1.0 0.8 0.6 0.4 0.2 0.0 Log-rank test, p = 0.010 Ibutilide responders Ibutilide non-responders Fig. 2. Kaplan–Meier curves of long-term clinical outcome in patients with non-paroxysmal AF after the first (A) and the second (B) catheter ablation. A B
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