Mid-term follow-up of atrioventricular node ablation and conduction system pacing without a ventricular backup lead in atrial fibrillation-induced tachycardiomyopathy - a single-center experience
Authors: Pestrea C G , Cicala E , Ivascu M , Ortan F O , Pop D 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.
In the permanent form of atrial fibrillation (AF), ablation is not recommended or has failed and the only option is rate control. The most effective rate control strategy is atrioventricular node (AVN) ablation, but this renders the patient pacing-dependent. Several observational studies have shown that both His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), provide a narrower QRS complex and a more synchronous ventricular activation compared to right ventricular pacing. Current guidelines recommend placing a ventricular backup lead as a safety measure. We present our mid-term follow-up data on the feasibility of AVN ablation and physiological pacing without a ventricular backup lead in patients with tachycardiomyopathy due to rapidly conducted permanent AF.

MATERIAL AND METHODS
A total of 25 patients with permanent AF and HF and rate control failure with AVN-blocking drugs, that underwent physiological pacing and AVN ablation at our institution, were included in this retrospective review. During the procedure, HBP was the first option, followed by LBBAP if the His bundle was not captured at a threshold below 2.5V at 1 ms. The lead was connected to a single chamber pacemaker, without a backup pacing lead. In the same setting, using a femoral vein approach, a 4-mm tip ablation catheter was used to perform AVN ablation. Patient and procedural characteristics were recorded as well as the electrical parameters and complications at the follow-up visits.

Results
The mean age of the patients was 69 ± 12.4 years and 64% were males. The heart rate was 133±20.43 bpm and the ejection fraction was 28.84±9.02 %. 17 patients had normal QRS complex, 3 had right bundle branch block and 5 had left bundle branch block patterns. HBP was successful in 9 patients (36%) and LBBAP in 16 patients (64%). In patients with a baseline-wide QRS, physiological pacing significantly reduced the QRS duration (135.25±17.58 vs. 159±32.38 ms, p=0.04). The paced QRS complex was significantly narrower in HBP than LBBAP (95.67±14.37 vs. 129.88±17.46 ms, p&lt;0.001). There was a significantly lower pacing threshold for LBBAP (0.77±0.3 V at 1 ms vs. 0.87±0.72 V at 0.4 ms, p&lt;0.05) and better sensitivity for LBBAP (6.23±4.56 mV vs. 10.2±5.19 mV, p=0.66). The fluoroscopy time was non-statistically different between HBP and LBBAP (13.21±15.47 min vs. 18.72±12.95 min, p=0.35). AV node ablation was successful in all patients. The mean follow-up period was 524±110.2 days. 11 patients became pacemaker-dependent. There was no significant difference in pacing thresholds for both LBBAP (0.67±0.27 V at 0.4 ms, p=0.24) and HBP (0.87±0.56 V at 1 ms, p=0.485) patients and there was no recurrence in AV node conduction. No lead dislodgements were recorded.

Conclusions
AVN ablation and physiological pacing is feasible and safe without the need for a backup ventricular pacing lead, thus minimizing the risks and costs associated with a higher lead burden.