Randomised, blinded and controlled comparative study of chemical and radiofrequency-based renal denervation in a porcine model

Aims: The blood pressure-lowering effect of percutaneous renal denervation (RDN) is controversial. The success of RDN may be device-dependent. We sought to compare the efficacy of RDN by chemical neurolysis using alcohol (Peregrine System Infusion Catheter; Ablative Solutions, Inc., Menlo Park, CA, USA) to RDN by radiofrequency (RF) ablation with the single-electrode RF catheter (Symplicity Flex; Medtronic, Minneapolis, MN, USA) in a porcine model. Methods and results: This was a prospective, randomised, blinded study. Pigs were assigned to undergo bilateral RF ablation or chemical neurolysis. Primary endpoints were ablation depth and renal tissue norepinephrine (NE) concentrations at three-month follow-up. Twelve pigs underwent RF ablation (n=4) or chemical neurolysis by infusion of 0.3 mL (n=4) or 0.6 mL (n=4) alcohol. Ninety days after RF ablation and chemical neurolysis with 0.3 mL and 0.6 mL of alcohol, mean maximal tissue injury depth was 3.9±1.2 mm, 6.6±1.7 mm and 8.2±2.2 mm, respectively (p<0.001 for either dose of alcohol vs. RF ablation). Compared with historical controls, median renal tissue NE concentration reductions were 66%, 78% and 83% after RF ablation and chemical neurolysis using 0.3 mL and 0.6 mL alcohol, respectively (p=0.107 for chemical neurolysis vs. RF ablation). Mean total ablation area was significantly greater in both (0.3 mL and 0.6 mL) alcohol groups (p=0.0001 for both) than the RF ablation group (30.8±13.7 mm2, 41.6±12.4 mm2 and 11.0±7.5 mm2, respectively). Conclusions: RDN is more effective using chemical neurolysis than single-electrode RF ablation. Our findings suggest that the efficacy of RDN may be device-dependent.