Ablate and Pace HIS Study

Overview

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and estimates suggest its prevalence is increasing. Despite the advances in AF ablation strategies, the outcome of ablation procedures in persistent AF is still unsatisfactory. In addition, many patients are not candidates for ablation due to advanced age, comorbidities and previous failed ablation procedures. It is well known that there is no mortality benefit from rhythm versus rate control strategy in AF, therefore the increased number of AV node ablation and pacemaker insertion for patients with symptomatic AF with uncontrolled heart rate. Following AV node ablation, it is understandable that these patients will be paced 100% of the time where the value of physiological pacing will be at its most. The current standard practice is to pace the right ventricle for this cohort of patients unless they have severe LV systolic dysfunction when a biventricular pacing might be recommended. Previous data showed that RV pacing only can lead to deterioration of LV function, worsening of heart failure symptoms and increased mortality. HIS bundle pacing is a novel technique of pacing through placing the pacemaker lead on the junction box between the top and bottom chamber of the heart. This will allow the utilisation of the normal/intrinsic HIS Purkinjie (eclectic cables) to stimulate the ventricles. This can offer a physiological pacing modality and reduce pacing induced cardiomyopathy specially in pacing dependent pacing. The Ablate and Pace HIS Study proposes that the new method of HIS pacing is safe, effective and superior to the existing method of RV pacing in patients with atrial fibrillation who demonstrate signs of heart failure.

The Ablate and Pace HIS Study is a single-centre, prospective randomised single-blinded study, recruiting a sub-population of patients with AF who are deemed not fit for rhythm control strategy. These patients have been referred for a pacemaker implant and AVN node ablation as a symptomatic rate control option. The study aims to randomise a total of 100 participants into either the RV only pacing arm or the HBP arm. All patients will be implanted with a pacemaker device with one lead positioned in the right ventricle, and only in the HBP arm will an additional lead be positioned on the distal HIS bundle in order to obtain direct HIS-bundle capture. The RV lead will be only be used as a back-up option for the HBP arm if needed. Participants will undergo AVN ablation either at the same setting or 4-6 weeks later according to clinical indication and operator preference. A double-blinded design will then be employed to investigate the effect of HIS pacing. Endpoint measurements will be taken at Baseline, 4 weeks, 6 months and 12 months post randomisation. Treatment allocation will be blinded to the patients and endpoint assessor. All participants will be informed of their allocated treatment arm at the end of their 12 month follow up visit. Funding has been provided by Medtronic. The study Sponsor is University Hospitals of Leicester.