Predictive factors for successful renal denervation: should we use them in clinical trials?

Selective Renal Denervation Guided by Renal Nerve Stimulation in Canine

Renal nerve stimulation (RNS) can result in substantial blood pressure (BP) elevation, and the change was significantly blunted when repeated stimulation after ablation. However, whether RNS could provide a meaningful renal nerve mapping for identification of optimal ablation targets in renal denervation (RDN) is not fully clear. Here, we compared the antihypertensive effects of selective RDN guided by two different BP responses to RNS and explored the nerve innervations at these sites in Kunming dogs. Our data indicated that ablation at strong-response sites showed a more systolic BP-lowering effect than at weak-response sites ( P =0.002), as well as lower levels of tyrosine hydroxylase and norepinephrine in kidney and a greater reduction in plasma norepinephrine ( P =0.004 for tyrosine hydroxylase, P =0.002 for both renal and plasma norepinephrine). Strong-response sites showed a greater total area and mean number of renal nerves than weak-response sites ( P =0.012 for total area and P <0.001 for mean number). Systolic BP-elevation response to RNS before RDN and blunted systolic BP-elevation to RNS after RDN were correlated with systolic BP changes at 4 weeks follow-up ( R =0.649; P =0.012 and R =0.643; P =0.013). Changes of plasma norepinephrine and renal norepinephrine levels at 4 weeks were also correlated with systolic BP changes at 4 weeks ( R =0.837, P <0.001 and R =0.927, P <0.001). These data suggest that selective RDN at sites with strong BP-elevation response to RNS could lead to a more efficient RDN. RNS is an effective method to identify the nerve-enriched area during RDN procedure and improve the efficacy of RDN.

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)?

INTRODUCTION

Disturbance of sympathetic and vagal nervous system participates in the pathogenesis of hypertension and atrial fibrillation (AF). Renal denervation (RDN) can modulate autonomic nervous activity and reduce blood pressure (BP) in hypertensive patients. We aimed to evaluate the effect of RDN combined with pulmonary vein isolation (PVI) in patients with AF and hypertension.

METHODS

Clinical trials including randomized data comparing PVI plus RDN vs PVI alone were enrolled. Primary outcome was incidence of AF recurrence after procedure.

RESULTS

A total of 387 patients, of them 252 were randomized and were enrolled. Mean age was 57 ± 10 years, 71% were male, and mean left ventricular ejection fraction was 57.4% ± 6.9%. Follow-up for randomized data was 12 months. Overall comparison for primary outcome showed that PVI + RDN was associated with significantly lower AF recurrence as compared with PVI alone (35.8% vs 55.4%, P < 0.0001). This advantageous effect was consistently maintained among randomized patients (37.3% vs 61.9%, odds ratio = 0.37, P = 0.0001), and among patients with implanted devices for detection of AF recurrence (38.9% vs 61.6%, P = 0.007). Post-hoc sensitivity and regression analysis demonstrated very good stability of this primary result. Pooled Kaplan-Meier analysis further showed that PVI + RDN was associated with significantly higher freedom from AF recurrence as compared with PVI alone (log-rank test, P = 0.001). Besides, RDN resulted in significant BP reduction without additionally increasing the risk of adverse events.

CONCLUSIONS

RDN may provide synergetic effects with PVI to reduce the burden of AF and improve BP control in patients with AF and uncontrolled hypertension.

Modulation of renal sympathetic innervation: recent insights beyond blood pressure control

Renal afferent and efferent sympathetic nerves are involved in the regulation of blood pressure and have a pathophysiological role in hypertension. Additionally, several conditions that frequently coexist with hypertension, such as heart failure, obstructive sleep apnea, atrial fibrillation, renal dysfunction, and metabolic syndrome, demonstrate enhanced sympathetic activity. Renal denervation (RDN) is an approach to reduce renal and whole body sympathetic activation. Experimental models indicate that RDN has the potential to lower blood pressure and prevent cardio-renal remodeling in chronic diseases associated with enhanced sympathetic activation. Studies have shown that RDN can reduce blood pressure in drug-naïve hypertensive patients and in hypertensive patients under drug treatment. Beyond its effects on blood pressure, sympathetic modulation by RDN has been shown to have profound effects on cardiac electrophysiology and cardiac arrhythmogenesis. RDN can display anti-arrhythmic effects in a variety of animal models for atrial fibrillation and ventricular arrhythmias. The first non-randomized studies demonstrate that RDN may promote the maintenance of sinus rhythm following catheter ablation in patients with atrial fibrillation. Registry data point towards a beneficial effect of RDN to prevent ventricular arrhythmias in patients with heart failure and electrical storm. Further large randomized placebo-controlled trials are needed to confirm the antihypertensive and anti-arrhythmic effects of RDN. Here, we will review the current literature on anti-arrhythmic effects of RDN with the focus on atrial fibrillation and ventricular arrhythmias. We will discuss new insights from preclinical and clinical mechanistic studies and possible clinical implications of RDN.