Renal denervation for treatment of hypertension and beyond
In the letter to the editor ‘‘Renal denervation as a friend of catheter ablation in patients with atrial fibrillation and hypertension’’, Zhang et al. [1] summarize several studies supporting the beneficial effect of renal denervation (RDN) in patients with atrial fibrillation undergoing catheter-based pulmonary vein isolation discussed in our recent review [2]. They also mention the potential antiarrhythmic effects of RDN on ventricular arrhythmias. While quite a lot of basic and clinical studies were performed to investigate the effect of RDN on atrial arrhythmias [3], the effect on ventricular electrophysiology and arrhythmogenesis is less clear. The autonomic nervous system is known to play a role in the genesis and maintenance of ventricular arrhythmias [4]. Currently, antiarrhythmic therapies and catheter ablation represent the standard of care in patients with recurrent ventricular tachyarrhythmia and implantable cardioverter-defibrillator (ICD) shocks. Neuromodulation is emerging as an alternative therapy supported by beneficial effects of thoracic epidural anesthesia, cardiac sympathetic denervation, and spinal cord stimulation shown in animal models and case series of patients with and without cardiomyopathy [4]. In a pig model, RDN reduced the occurrence of ventricular ectopics and ventricular fibrillation after acute myocardial ischemia, while reperfusion arrhythmias were not diminished [5]. Additionally, at least three case series have provided promising data on the safety and effectiveness of RDN alone or as an adjunctive therapy in the treatment of patients with ischemic or dilated cardiomyopathy and treatment-resistant ventricular tachyarrhythmias [6–8]. Several mechanisms like attenuation of structural changes in the ventricle as well as prevention of ventricular ectopies representing potential triggers for ventricular arrhythmias may underly the clinically observed antiarrhythmic effect by RDN [9]. In summary, besides blood pressure control, modulation of the sympathetic nervous system remains a promising research target in several conditions associated with an elevated sympathetic activity. Randomized placebo-controlled studies are needed to show whether sympathetic inhibition by RDN exerts antiarrhythmic effects and improves ablation outcome in both, the atrium and the ventricle.