Synergy of pulmonary vein isolation and catheter renal denervation in atrial fibrillation complicated with uncontrolled hypertension: Mapping the renal sympathetic nerve and pulmonary vein (the pulmonary vein isolation plus renal denervation strategy)?

The Role of the Autonomic Nervous System as Both "Trigger and "Substrate" in Atrial Fibrillation

Several complex mechanisms, working alone, or together, initiate and maintain atrial fibrillation (AF). At disease onset, pulmonary vein-atrial triggers, producing ectopy, predominate. Then, as AF progresses, a shift toward substrate occurs, which AF also self-perpetuates. The autonomic nervous system (ANS) plays an important role as trigger and substrate. Although the efferent arm of the ANS as AF trigger is well-established, there is emerging evidence to show that (1) the ANS is a substrate for AF and (2) afferent or regulatory ANS dysfunction occurs in AF patients. These findings could represent a mechanism for the progression of AF.

Renal Denervation for Patients With Atrial Fibrillation

PURPOSE OF REVIEW

During the last decade, several case series and small reports have indicated that pulmonary vein isolation (PVI) in combination with renal denervation (RDN) may increase the rate of atrial fibrillation (AF) freedom in patients with hypertension. We aimed to provide a contemporary systematic overview on the techniques, and the efficacy/safety of RDN on AF recurrence, and the current landscape of ongoing investigation.

RECENT FINDINGS

The recent Evaluate Renal Denervation in Addition to Catheter Ablation to Eliminate Atrial Fibrillation (ERADICATE-AF) trial has demonstrated convincingly that among patients with paroxysmal AF and poorly controlled (but not "resistant") hypertension, RDN added to catheter ablation, compared with catheter ablation alone, significantly increased the likelihood of freedom from AF at 12 months. RDN has proven to be a unique, effective and safe interventional therapy for the management of AF. Future investigation will likely focus on confirming current findings; expanding the population of eligible patients (eg., non-hypertensives, well controlled hypertensives); determining long-term maintenance of effect and therapeutics.

Neuroscientific therapies for atrial fibrillation

The cardiac autonomic nervous system (ANS) plays an integral role in normal cardiac physiology as well as in disease states that cause cardiac arrhythmias. The cardiac ANS, comprised of a complex neural hierarchy in a nested series of interacting feedback loops, regulates atrial electrophysiology and is itself susceptible to remodelling by atrial rhythm. In light of the challenges of treating atrial fibrillation (AF) with conventional pharmacologic and myoablative techniques, increasingly interest has begun to focus on targeting the cardiac neuraxis for AF. Strong evidence from animal models and clinical patients demonstrates that parasympathetic and sympathetic activity within this neuraxis may trigger AF, and the ANS may either induce atrial remodelling or undergo remodelling itself to serve as a substrate for AF. Multiple nexus points within the cardiac neuraxis are therapeutic targets, and neuroablative and neuromodulatory therapies for AF include ganglionated plexus ablation, epicardial botulinum toxin injection, vagal nerve (tragus) stimulation, renal denervation, stellate ganglion block/resection, baroreceptor activation therapy, and spinal cord stimulation. Pre-clinical and clinical studies on these modalities have had promising results and are reviewed here.

Renal Sympathetic Denervation as Upstream Therapy During Atrial Fibrillation Ablation: Pilot HFIB Studies and Meta-Analysis

OBJECTIVES

This study sought to determine the impact of adjunctive renal sympathetic denervation to catheter ablation in patients with atrial fibrillation (AF) and history of hypertension.

BACKGROUND

There are limited data regarding the impact of upstream adjunctive renal sympathetic denervation (RSDN) to pulmonary vein isolation (PVI) in patients with symptomatic atrial fibrillation (AF) and hypertension.

METHODS

The data for this study were obtained from 2 prospective randomized pilot studies, the HFIB (Adjunctive Renal Denervation to Modify Hypertension and Sympathetic tone as Upstream Therapy in the Treatment of Atrial Fibrillation)-1 (n = 30) and HFIB (Adjunctive Renal Denervation to Modify Hypertension and Sympathetic tone as Upstream Therapy in the Treatment of Atrial Fibrillation)-2 (n = 50) studies, and we performed a meta-analysis including all published studies comparing RSDN+PVI versus PVI alone up to January 25, 2020, in patients with AF and hypertension.

RESULTS

At 24 months, AF recurrence occurred in 53% and 38% in the PVI and PVI+RSDN groups (p = 0.43) in the HFIB-1 study, respectively, and 27% and 25% in the PVI and PVI+RSDN groups (p = 0.80) in the HFIB-2 study, respectively. When combined in a meta-analysis including 6 studies (n = 725), adjunctive RSDN significantly decreased the risk of AF recurrence (risk ratio [RR]: 0.68; 95% confidence interval [CI]: 0.55 to 0.83; p = 0.0002; I² = 0%) when compared with PVI. Six renal artery complications occurred in the HFIB-1 study and none occurred in the HFIB-2 study with RSDN. However, in the meta-analysis, there were no significant differences in overall complications between both groups (RR: 1.43; 95% CI: 0.63 to 3.22; p = 0.40; I² = 7%). When compared with baseline, RDSN significantly reduced the systolic blood pressure (-12.1 mm Hg; 95% CI: -20.9 to -3.3 mm Hg; p < 0.007; I² = 99%) and diastolic blood pressure (-5.60 mm Hg; 95% CI: -10.05 to -1.10 mm Hg; p = 0.01; I² = 98%) on follow-up.

CONCLUSIONS

The pilot HFIB-1 and HFIB-2 studies did not demonstrate a benefit with RSDN as an adjunctive upstream therapy during PVI. However, in the meta-analysis, adjunctive RSDN to PVI appears to be safe, and improves clinical outcomes in AF patients with a history of hypertension.