Catheter-based renal denervation as adjunct to pulmonary vein isolation for treatment of atrial fibrillation: a systematic review and meta-analysis

Catheter-based renal artery denervation: facts and expectations

Catheter-based renal artery denervation (RAD) is entering a new era. After the disappointing results of SYMPLICITY-HTN 3 trial in year 2014, several technical and methodological advancements led to execution of important SHAM-controlled randomized trials with promising results. Now, the 2023 ESH Guidelines give RAD a class of recommendation II with a Level of Evidence B. Currently, catheter-based RAD has two main areas of application: (a) Hypertensive patients who are still untreated, in whom RAD is a sort of a first-line treatment; (b) Difficult-to-control or true resistant hypertensive patients. Notably, randomized SHAM-controlled trials met their primary end-point in both these conditions. So far, we do not dispose of established predictors of the antihypertensive response to RAD. Some data suggest that younger patients with systo-diastolic hypertension, absence of diffuse atherosclerosis and evidence of sympathetic nervous system overactivity experience a better BP response to the procedure. We reviewed the available data on catheter-based RAD and included an updated meta-analysis of the results of the available SHAM-controlled trials. Overall, the reduction in 24-h systolic blood pressure (BP) after RAD exceeded that after SHAM by 4.58 mmHg (95% CI 3.07-6.10) in untreated patients, and by 3.82 mmHg (95% CI 2.46-5.18) in treated patients, without significant heterogeneity across trials, patient phenotype (untreated versus treated patients) and technique (radiofrequency versus ultrasound). There were no important safety signals related to the procedure. Notably, some data suggest that RAD could be an effective additional approach in patients with atrial fibrillation and other conditions characterized by sympathetic nervous system overactivity.

Autonomic Modulation of Atrial Fibrillation

The autonomic nervous system plays a vital role in cardiac arrhythmias, including atrial fibrillation (AF). Therefore, reducing the sympathetic tone via neuromodulation methods may be helpful in AF control. Myocardial ischemia is associated with increased sympathetic tone and incidence of AF. It is an excellent disease model to understand the neural mechanisms of AF and the effects of neuromodulation. This review summarizes the relationship between autonomic nervous system and AF and reviews methods and mechanisms of neuromodulation. This review proposes that noninvasive or minimally invasive neuromodulation methods will be most useful in the future management of AF.

Renal denervation alleviates chronic obstructive sleep apnea-induced atrial fibrillation via inhibition of atrial fibrosis and sympathetic hyperactivity

OBJECTIVE

Previous studies have reported that renal denervation (RDN) prevents the occurrence of atrial fibrillation (AF) related to obstructive sleep apnea (OSA). However, the effect of RDN on chronic OSA (COSA)-induced AF is still unclear.

METHODS

Healthy beagle dogs were randomized into the OSA group (sham RDN + OSA), OSA-RDN group (RDN + OSA), and CON group (sham RDN + sham OSA). The COSA model was built via repeated apnea and ventilation rounds for 4 h each day lasting 12 weeks, and RDN was employed after 8 weeks of modeling. All dogs were implanted Reveal LINQ™ to detect spontaneous AF and AF burden. Circulating levels of norepinephrine, angiotensin II, and interleukin-6 were determined at baseline and end of the study. In addition, measurements of the left stellate ganglion, AF inducibility, and effective refractory period were conducted. The bilateral renal artery and cortex, left stellate ganglion, and left atrial tissues were collected for molecular analysis.

RESULTS

Of 18 beagles, 6 were randomized to each of the groups described above. RDN remarkably attenuated ERP prolongation and AF episodes and duration. RDN markedly suppressed the LSG hyperactivity and atrial sympathetic innervation, decreased the serum concentrations of Ang II and IL-6, further inhibited fibroblast-to-myofibroblast transformation via the TGF-β1/Smad2/3/α-SMA pathway, and reduced the expression of MMP-9, thus decreasing OSA-induced AF.

CONCLUSIONS

RDN may reduce AF by inhibiting sympathetic hyperactivity and AF in a COSA model.

Tic-Tac: A Translational Approach in Mechanisms Associated with Irregular Heartbeat and Sinus Rhythm Restoration in Atrial Fibrillation Patients

Atrial fibrillation (AF) is a prevalent cardiac condition predominantly affecting older adults, characterized by irregular heartbeat rhythm. The condition often leads to significant disability and increased mortality rates. Traditionally, two therapeutic strategies have been employed for its treatment: heart rate control and rhythm control. Recent clinical studies have emphasized the critical role of early restoration of sinus rhythm in improving patient outcomes. The persistence of the irregular rhythm allows for the progression and structural remodeling of the atria, eventually leading to irreversible stages, as observed clinically when AF becomes permanent. Cardioversion to sinus rhythm alters this progression pattern through mechanisms that are still being studied. In this review, we provide an in-depth analysis of the pathophysiological mechanisms responsible for maintaining AF and how they are modified during sinus rhythm restoration using existing therapeutic strategies at different stages of clinical investigation. Moreover, we explore potential future therapeutic approaches, including the promising prospect of gene therapy.

Hypertension and atrial fibrillation

Hypertension is the most prevalent cardiovascular risk factor underlying atrial fibrillation and is present in up to 40% of patients with atrial fibrillation. Furthermore, attributable risk studies have shown that a history of hypertension contributes to up to 24% of incident atrial fibrillation. New data suggest that even early forms of hypertension (prehypertension and aortic stiffness) are associated with an increased risk of atrial fibrillation development. Hypertension and prehypertension are therefore critical mediators for the development of atrial fibrillation. Mechanisms for the association between hypertension and atrial fibrillation include diffuse electro-structural changes to the left atrium, driven by the haemodynamic and neurohormonal influences of hypertension and other, frequently coexisting, cardiovascular risk factors. Management of hypertension in atrial fibrillation should focus not only on blood pressure reduction but also on a comprehensive risk factor modification strategy. Such strategies have been shown to be associated with significant improvements in atrial fibrillation symptom burden as well as improved arrhythmia-free survival and reversal of the progression of atrial fibrillation. These strategies should focus on dietary modifications as well as prescribed exercise programmes involving a multidisciplinary team and patient-centred atrial fibrillation care. Risk factor management, supplemented by antihypertensive medications as needed, provides the optimum strategy for improving outcomes and even reversing the natural progression of atrial fibrillation in patients with hypertension.

Hypertension management in patients with cardiovascular comorbidities

Arterial hypertension is a leading cause of death globally. Due to ageing, the rising incidence of obesity, and socioeconomic and environmental changes, its incidence increases worldwide. Hypertension commonly coexists with Type 2 diabetes, obesity, dyslipidaemia, sedentary lifestyle, and smoking leading to risk amplification. Blood pressure lowering by lifestyle modifications and antihypertensive drugs reduce cardiovascular (CV) morbidity and mortality. Guidelines recommend dual- and triple-combination therapies using renin–angiotensin system blockers, calcium channel blockers, and/or a diuretic. Comorbidities often complicate management. New drugs such as angiotensin receptor-neprilysin inhibitors, sodium–glucose cotransporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, and non-steroidal mineralocorticoid receptor antagonists improve CV and renal outcomes. Catheter-based renal denervation could offer an alternative treatment option in comorbid hypertension associated with increased sympathetic nerve activity. This review summarises the latest clinical evidence for managing hypertension with CV comorbidities.

Renal denervation in the antihypertensive arsenal - knowns and known unknowns

Even though it has been more than a decade since renal denervation (RDN) was first used to treat hypertension and an intense effort on researching this therapy has been made, it is still not clear how RDN fits into the antihypertensive arsenal. There is no question that RDN lowers blood pressure (BP), it does so to an extent at best corresponding to one antihypertensive drug. The procedure has an excellent safety record. However, it remains clinically impossible to predict whose BP responds to RDN and whose does not. Long-term efficacy data on BP reduction are still unconvincing despite the recent results in the SPYRAL HTN-ON MED trial; experimental studies indicate that reinnervation is occurring after RDN. Although BP is an acceptable surrogate endpoint, there is complete lack of outcome data with RDN. Clear indications for RDN are lacking although patients with resistant hypertension, those with documented increase in activity of the sympathetic system and perhaps those who desire to take fewest medication may be considered.

Clinical Trial Design Principles and Outcomes Definitions for Device-Based Therapies for Hypertension: A Consensus Document From the Hypertension Academic Research Consortium

The clinical implications of hypertension in addition to a high prevalence of both uncontrolled blood pressure and medication nonadherence promote interest in developing device-based approaches to hypertension treatment. The expansion of device-based therapies and ongoing clinical trials underscores the need for consistency in trial design, conduct, and definitions of clinical study elements to permit trial comparability and data poolability. Standardizing methods of blood pressure assessment, effectiveness measures beyond blood pressure alone, and safety outcomes are paramount. The Hypertension Academic Research Consortium (HARC) document represents an integration of evolving evidence and consensus opinion among leading experts in cardiovascular medicine and hypertension research with regulatory perspectives on clinical trial design and methodology. The HARC document integrates the collective information among device-based therapies for hypertension to better address existing challenges and identify unmet needs for technologies proposed to treat the world’s leading cause of death and disability. Consistent with the Academic Research Consortium charter, this document proposes pragmatic consensus clinical design principles and outcomes definitions for studies aimed at evaluating device-based hypertension therapies.

Renal Denervation Prevents Atrial Arrhythmogenic Substrate Development in CKD

BACKGROUND

In patients with chronic kidney disease (CKD), atrial fibrillation (AF) is highly prevalent and represents a major risk factor for stroke and death. CKD is associated with atrial proarrhythmic remodeling and activation of the sympathetic nervous system. Whether reduction of the sympathetic nerve activity by renal denervation (RDN) inhibits AF vulnerability in CKD is unknown.

METHODS

Left atrial (LA) fibrosis was analyzed in samples from patients with AF and concomitant CKD (estimated GFR, <60 mL/min per 1.73 m²) using picrosirius red and compared with AF patients without CKD and patients with sinus rhythm with and without CKD. In a translational approach, male Sprague Dawley rats were fed with 0.25% adenine (AD)-containing chow for 16 weeks to induce CKD. At week 5, AD-fed rats underwent RDN or sham operation (AD). Rats on normal chow served as control. After 16 weeks, cardiac function and AF susceptibility were assessed by echocardiography, radiotelemetry, electrophysiological mapping, and burst stimulation, respectively. LA tissue was histologically analyzed for sympathetic innervation using tyrosine hydroxylase staining, and LA fibrosis was determined using picrosirius red.

RESULTS

Sirius red staining demonstrated significantly increased LA fibrosis in patients with AF+CKD compared with AF without CKD or sinus rhythm. In rats, AD demonstrated LA structural changes with enhanced sympathetic innervation compared with control. In AD, LA enlargement was associated with prolonged duration of induced AF episodes, impaired LA conduction latency, and increased absolute conduction inhomogeneity. RDN treatment improved LA remodeling and reduced LA diameter compared with sham-operated AD. Furthermore, RDN decreased AF susceptibility and ameliorated LA conduction latency and absolute conduction inhomogeneity, independent of blood pressure reduction and renal function.

CONCLUSIONS

In an experimental rat model of CKD, RDN inhibited progression of atrial structural and electrophysiological remodeling. Therefore, RDN represents a potential therapeutic tool to reduce the risk of AF in CKD, independent of changes in renal function and blood pressure.

Renal denervation for atrial fibrillation: a comprehensive updated systematic review and meta-analysis

The study aims to compare clinical outcomes following renal denervation (RDN) in hypertensive patients with atrial fibrillation (AF). Three online databases were searched (MEDLINE, EMBASE and PubMed) for literature related to outcomes of RDN on hypertension and AF, between January 1, 2010, and June 1, 2021. Where possible, risk ratios (RR) and mean differences (MD) were combined using a random effects model. Significance was set at p ≤ 0.05. Seven trials were included that assessed the effect of adding RDN to pulmonary vein isolation (PVI) in patients with hypertension and AF. A total of 711 patients (329 undergoing PVI + RDN and 382 undergoing PVI alone), with an age range of 56 ± 6 to 68 ± 9 years, were included. Pooled analysis showed a significant lowering of AF recurrence in the PVI + RDN (31.3%) group compared to the PVI-only (52.9%) group (p < 0.00001). Pooled analysis of patients with resistant hypertension showed a significant mean reduction of systolic blood pressure (SBP) (-9.42 mm Hg, p = 0.05), but not diastolic blood pressure (DBP) (-4.11 mm Hg, p = 0.16) in favor of PVI + RDN. Additionally, the pooled analysis showed that PVI + RDN significantly improved estimated glomerular filtration rate (eGFR) (+10.2 mL/min per 1.73 m², p < 0.001) compared to PVI alone. RDN procedures in these trials have proven to be both safe and efficacious with an overall complication rate of 6.32%. Combined PVI and RDN is beneficial for patients with hypertension and AF. Combined therapy showed improvement in SBP and eGFR, reducing the risk of AF recurrence. RDN may serve as an innovative intervention in the treatment of AF.

Catheter-Based Renal Denervation Therapy: Evolution of Evidence and Future Directions

Motivated by the persistence of uncontrolled blood pressure and its public health impact, the development and evaluation of device-based therapies for hypertension has advanced at an accelerated pace to complement pharmaceutical and lifestyle intervention strategies. Countering widespread interest from early studies, the lack of demonstrable efficacy for renal denervation (RDN) in a large, sham-controlled randomized trial motivated revision of trial design and conduct to account for confounding variables of procedural technique, medication variability, and selection of both patients and end points. Now amidst varied trial design and methods, several sham-controlled, randomized trials have demonstrated clinically meaningful reductions in blood pressure with RDN. With this momentum, additional studies are underway to position RDN as a potential part of standard therapy for the world's leading cause of death and disability. In parallel, further studies will address unresolved issues including durability of blood pressure lowering and reduction in antihypertensive medications, late-term safety, and impact on clinical outcomes. Identifying predictors of treatment effect and surveys of patient-reported outcomes and treatment preferences are also evolving areas of investigation. Aside from confirmatory studies of safety and effectiveness, these additional studies will further inform patient selection, expand experience with RDN in broader populations with hypertension, and provide guidance to how RDN may be incorporated into treatment pathways.

Systematic review of renal denervation for the management of cardiac arrhythmias

Background

In the wake of the controversy surrounding the SYMPLICITY HTN-3 trial and data from subsequent trials, this review aims to perform an updated and more comprehensive review of the impact of renal sympathetic denervation on cardiac arrhythmias.

Methods and results

A systematic search was performed using the Medline, Scopus and Embase databases using the terms “Renal Denervation” AND “Arrhythmias or Atrial or Ventricular”, limited to Human and English language studies within the last 10 years. This search yielded 19 relevant studies (n = 6 randomised controlled trials, n = 13 non-randomised cohort studies) which comprised 783 patients. The studies show RSD is a safe procedure, not associated with increases in complications or mortality post-procedure. Importantly, there is no evidence RSD is associated with a deterioration in renal function, even in patients with chronic kidney disease. RSD with or without adjunctive pulmonary vein isolation (PVI) is associated with improvements in freedom from atrial fibrillation (AF), premature atrial complexes (PACs), ventricular arrhythmias and other echocardiographic parameters. Significant reductions in ambulatory and office blood pressure were also observed in the majority of studies.

Conclusion

This review provides evidence based on original research that ‘second generation’ RSD is safe and is associated with reductions in short-term blood pressure and AF burden. However, the authors cannot draw firm conclusions with regards to less prominent arrhythmia subtypes due to the paucity of evidence available. Large multi-centre RCTs investigating the role of RSD are necessary to comprehensively assess the efficacy of the procedure treating various arrhythmias.

Graphic abstract

Renal arteries denervation: from the treatment of resistant hypertension to the treatment of atrial fibrillation

Renal denervation (RDN) is a therapeutic strategy for patients with uncontrolled arterial hypertension characterized by considerable fluctuations during its progression. After initial strong enthusiasm, the procedure came to an abrupt halt following the publication of the Symplicity HTN-3 study results. The results of recently published studies highlight the reduction in blood pressure values after RDN and justify the inclusion in the Guidelines of new recommendations for the use of RDN in clinical practice, in selected patients. Additionally, RDN findings are summarized in view of other potential indications such as atrial fibrillation. Six prospective, randomized studies are presented that evaluated RDN as an adjunct therapy to pulmonary vein isolation for the treatment of atrial fibrillation. In five studies, patients had uncontrolled hypertension despite therapy with three antihypertensive drugs. The analysis of these studies showed that RDN reduced the recurrence of atrial fibrillation (AF) by 57% compared to patients with pulmonary vein isolation (PVI) only. Modulation of the autonomic nervous system by RDN has been shown not only to reduce blood pressure but also to have an antiarrhythmic effect in symptomatic AF patients when the strategy is combined with PVI, thus opening up new therapeutic scenarios.

Renal denervation: can we press the "ON" button again in 2020?

In December 2018, an article summarizing available results of randomized studies on renal denervation (RDN), entitled "Renal denervation: can we press the ON button again?" was published in the Advances in Interventional Cardiology. Since then, several positive reports, including SPYRAL HTN OFF-MED Pivotal trial have been presented. In the current review the authors discuss the latest data on RDN in arterial hypertension treatment and try to answer the burning question: can we press the ON button again in 2020? The results of recently published studies potentially justify new recommendations for the use of RDN in clinical practice in appropriately selected patients in the new hypertension guidelines. The current review also summarizes the results of trials on RDN applied in another potential indication - atrial fibrillation. Six most important, prospective, randomized trials assessing RDN as adjunct therapy to pulmonary vein isolation for treatment of atrial fibrillation were discussed. In 5 studies, patients had uncontrolled BP despite treatment with three antihypertensive agents. The ratio for recurrence of atrial fibrillation for pulmonary vein isolation with RDN procedure was reduced by 57% as compared to pulmonary vein isolation (PVI) alone. BP was also reduced significantly after RDN in this subset of patients. Further multicenter studies involving standardized PVI and RDN procedures are needed.

Role of Ganglionated Plexus Ablation in Atrial Fibrillation on the Basis of Supporting Evidence

The role of the autonomic nervous system (ANS) in the onset and maintenance of atrial fibrillation (AF) may be related to autonomic imbalance. The ANS may cause specific cellular electrophysiological phenomena, such as, shortening of the atrial effective refractory periods (ERPs) and ectopy based on firing activity in pulmonary vein myocytes. High frequency stimulation of atrial ganglionated plexi (GPs) may cause an increase in ERP dispersion and induce AF. Autonomic modification strategies by targeting GPs with catheter ablation have emerged as new targets. Various strategies have been used to detect location of GPs.However, it is still not clear which is the best method to localize GPs, how many GPs should be targeted, and what are the long-term consequences of these therapies. In this review, we discuss available evidence on the clinical impact of GP ablation to treat AF.