AV nodal ablation, where are we now? Insight from real-world Northern Irish multi-centre registry data

Atrioventricular nodal (AVN) ablation with permanent pacemaker implantation – ‘pace and ablate’ – may be considered for patients with symptomatic atrial fibrillation (AF) for whom rhythm control has been unsuccessful. This creates concerns about inducing pacemaker dependence and potential pacemaker-induced cardiomyopathy (PICM). Conduction-system pacing mitigates PICM, so we expect a greater uptake of AVN ablation going forward.

We conducted a retrospective multi-centre review of our patients who underwent AVN ablation over a one-year period. AVN ablation was successful with durable lesions at one year. Radiofrequency energy was utilised in all patients, with a median application time of 2.67 minutes. Median procedure time was found to be 55.5 minutes and fluoroscopy median of 3.5 minutes. Median radiation dose was 11 mGy. We found no acute or subacute complications up to three months.

In conclusion, our right-sided approach for ablation, staged post-device insertion demonstrated results in keeping with other centres in the UK and Europe. We expect our current practice to become more widespread, given the increased risk of lead-related complications or failures associated with physiological pacing compared with standard pacing methods.

Introduction

Atrioventricular nodal (AVN) ablation with permanent pacemaker implantation – ‘pace and ablate’ – may be considered for patients with symptomatic atrial fibrillation (AF) for whom a rhythm control strategy has been unsuccessful.¹ Guidelines published by the European Society of Cardiology (ESC) in 2020 recommended this strategy with class IIA strength.² The decision by physicians to perform this procedure has been counterbalanced by the risk of pacemaker-induced cardiomyopathy (PICM) and heart failure due to excessive right ventricular (RV) pacing. Conduction-system pacing and left bundle branch area pacing (LBBAP) are strong mitigators of PICM in those who are pacemaker dependent when compared with RV pacing.³ It has been shown that AVN ablation and biventricular pacing, even in patients with a narrow QRS complex, provides a reduction in mortality when compared with rate control.⁴ Given the rise of conduction-system pacing in those who are pacing dependent, we expect a greater uptake of pace and ablate strategies in those with permanent symptomatic AF with preserved left ventricular (LV) function.⁵ As such, we undertook a real-world retrospective analysis of our patients who underwent AVN ablation to analyse current multi-centre procedural times and outcomes in the National Health Service (NHS) in Belfast, Northern Ireland.

Materials and method

Procedure

We conducted a retrospective multi-centre review of outcome data for our patients who underwent AVN ablation over a one-year period (April 2019 to March 2020). We included patients >18 years old who underwent AVN ablation using a ‘pace and ablate’ strategy for symptomatic AF, despite other techniques. Patients underwent RV dual-chamber permanent pacemaker (PPM) or cardiac resynchronisation therapy (CRT) insertion. Two centres that undertake high-volume ablation in Belfast, UK, were selected for our analysis.

A shared decision-making process was undertaken with patients prior to performing the procedure, which included informed consent being obtained. Oral anticoagulation medication was held on the morning of procedure (international normalised ratio [INR] target <3). Devices were checked to ensure stable parameters and reprogrammed to VVI (ventricular pacing and sensing) 30–40. Device pockets were checked to ensure no clinical evidence of infection. Local anaesthesia and sedation were administered. Ultrasound-guided right femoral vein access was performed as the first-line approach. Micro-puncture needles were used as initial access leading to 7 or 8 Fr sheath, depending on the ablation catheter size. Fluoroscopic placement of a non-irrigated ablation catheter (Marinr^TM, Medtronic, Minneapolis, USA) with 50 Watts, 50 °C setting was used. This was followed by localisation of His-bundle potential. Radiofrequency (RF) energy was applied and if AV dissociation developed, application was continued for one minute. This was followed by a 15-minute observation period, and if there was no recovery of AV conduction, sheaths were pulled, and pressure was applied to the groin access site. Devices were reprogrammed depending on the baseline heart rate (HR), e.g. base rate 90 bpm if device V-rate histograms were suggestive of longstanding tachycardia. Following the procedure, patients were instructed to remain in bed for three hours before being discharged home on the same day. Device base rates were reduced by 10 bpm weekly to a base rate of 70 VVI (same rate as in APAF-CRT).⁴

Statistical analysis

Performed using IBM SPSS Statistics Version 26 (IBM Corp, New York, USA).

Results

Patient characteristics

Inclusion criteria were met by 52 individuals (table 1): 54% were male (n=28) and the median age was 74 years (interquartile range [IQR] 67–82). There were 35% (n=18) of patients with paroxysmal AF, 23% (n=12) persistent AF and 42% (n=22) long-standing persistent AF. Other documented arrhythmias were present in 19% (n=10) of patients, including atrial flutter (four), ventricular tachycardia (three), supraventricular tachycardia (SVT, two) or atrial tachycardia (one). There were 17% (n=9) who had previous cardiac surgery, including coronary artery bypass graft (CABG) or valve replacements.

Left ventricular function (LVEF) prior to device implant was divided into four ordinal functional grades: normal (n=22), mildly impaired (n=5), moderately impaired (n=6) and severely impaired (n=19).

Procedure results

The timing of AVN ablation post-initial device insertion had a wide distribution of data with a rightward skew, with a median of three months and a mode of less than one month. All patients had successful AVN ablation with durable lesion creation. Radiofrequency energy was utilised in all patients, with a median application time of 2.67 minutes (IQR 2–5.4). Median skin-to-skin procedure time was found to be 55.5 minutes (IQR 43.75–73), with a fluoroscopy median time of 3.5 minutes (IQR 1.55–6.48). Median radiation dose was 11 mGy (IQR 4–16.27). There were 25 patients (48%) with biventricular pacing devices in situ and 27 patients (52%) implanted with a conventional RV pacemaker. Of those with a RV pacemaker, 23 patients had the lead implanted in the RV apex, and four patients had it implanted in the RV septum. There were no acute complications of the procedure. One patient death was recorded due to renal failure and one patient had a stroke within three months of the procedure, but neither of these were directly correlated.

Follow-up

From 52 patients, 38 had a follow-up LVEF assessment. Of the 25 patients with CRT: nine patients (36%) had no change in LVEF; five patients (20%) improved by one ordinal functional grade; three patients (12%) improved by two ordinal grades; five patients (20%) improved by three ordinal grades; one patient (4%) worsened by one ordinal grade and two patients (8%) did not have follow-up data. Average New York Heart Association (NYHA) class in this group upon follow-up was 1.9 (standard deviation [SD] 0.85).

In the non-CRT group, 15 patients had follow-up LVEF (55.6%). Two patients were paced from RV septum: one patient (50%) had no change in LV function and one patient (50%) improved by one functional group. Of those paced from RV apex, 13 patients had follow-up. One patient (7.6%) improved by two functional groups; one patient (7.6%) improved by one functional group; six patients (46%) remained the same; four patients (31%) worsened by one functional group and one patient (7.6%) worsened by three functional groups. The mean NYHA of the pacemaker group in follow-up was 2 (SD 0.84).

Discussion

Compared with other centres in the UK and Europe, our results are promising. Data on the utility of a left-sided approach have been mixed.^6–9 A right-sided approach, theoretically, carries less risk, not requiring access to the arterial system, and so, for us, this would only be an option in the setting of multiple failed right-sided procedures. Similar registry results were reported from Sweden, examining AVN ablations over 10 years demonstrating an adverse event rate of 0.87% (95% confidence interval [CI] 0.5 to 1.2%).¹⁰

When comparing our intra-procedural times, randomised data demonstrated a median fluoroscopy time of 4.7 minutes and median total procedure time of 49.5 minutes.¹¹ Notably, this was for AVN ablation only and did not include device insertion. Previous studies have similar RF ablation times of about two minutes.¹²

Across our centres, devices are inserted a median of three months in advance of AVN ablation. A recent study in Switzerland of 513 patients undergoing a pace and ablate strategy demonstrated that 70% of patients have their procedures performed in this way, however, 30% undergo both procedures at once.¹³ Due to the increased rate of lead-related complications associated with LBBAP,¹⁴ we anticipate that device pre-implantation will continue to predominate until physiological pacing techniques are refined.

In our cohort, 35% (n=18) had paroxysmal AF, 23% (n=12) persistent AF and 42% (n=22) long-standing persistent/permanent AF. This proportion of paroxysmal patients was higher than anticipated, however, on review of the cases, they were generally elderly patients, highly symptomatic, with significant structural heart disease and had recurrent arrhythmia despite ablation and anti-arrhythmic therapy.

Our centres implanted pacemakers in 52% of patients, with biventricular devices in 48%. While this resembles implant rates in other centres,¹⁵ we anticipate that the number of biventricular devices will continue to increase over time. Data suggest that CRT is superior to RV pacing after AVN ablation, regardless of LVEF, but this is more pronounced in those with impaired LV function.^16–18 We also anticipate that the number of physiological devices will markedly increase as more data become available. Moriña-Vázquez et al. examined outcomes in patients with permanent atrial arrhythmias with suboptimal rate control who underwent AVN ablation and permanent His-bundle pacing in a single centre. AVN ablation was successfully performed in all 39 patients, and no acute complications were reported. AVN ablation was performed, where possible, at least 15 days post-pacemaker implantation. In cases where patients were adjudicated to have an unstable clinical status due to tachycardia, AVN ablation was performed immediately post-pacemaker implantation. Like Manuel et al. they found significant improvements in NYHA class post-AVN ablation and CRT insertion.¹⁵ LVEF also improved in individuals who had an initial impaired LVEF, and remained stable in those with normal LVEF.¹⁹

Conclusion

Our multi-centre analysis provides evidence for AVN ablation with permanent device insertion. Our study identified no acute or subacute complications up to three months, with durable lesion creation and 100% ablation success in our cohort. Median fluoroscopy, procedure and radiofrequency times are comparable with other UK and European centres with a mean dose of 11 mGy. Eleven (21%) patients had biventricular devices, with the rest having dual-chamber pacemakers, which we expect to increase.

While most centres across the UK and Europe employ similar approaches, our right-sided approach with device insertion prior to ablation of the AVN enhanced the safety of our strategy, as lead and device functionality was known at time of committing to AVN ablation. This strategy was undertaken in all patients. This contrasts with some centres who achieve a 30% mix of devices on the same day as AVN ablation. We expect our current practice to become more widespread, given the increased risk of lead-related complications, or failures associated with physiological pacing compared with standard pacing methods.

Key messages

• Northern Irish multi-centre real-world registry data showed that a right-sided approach and staged procedures post-device insertion were the techniques of choice
• Real-world outcome data showed 100% durable lesion creation with no acute or subacute complications
• Procedure, fluoroscopy and radiofrequency application times were comparable with other cited data in larger UK and European centres

Conflicts of interest

None declared.

Funding

None.

Study approval

Requirement for ethical approval and consent was waived by the local hospitals audit departments as the study is a retrospective analysis of anonymised data.

References

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