Long‐Term Safety and Efficacy of Transcatheter Microwave and Radiofrequency Denervation in a Chronic Ovine Model

Background Transcatheter renal denervation (RDN) has had inconsistent efficacy and concerns for durability of denervation. We aimed to investigate long‐term safety and efficacy of transcatheter microwave RDN in vivo in normotensive sheep in comparison to conventional radiofrequency ablation. Methods and Results Sheep underwent bilateral RDN, receiving 1 to 2 microwave ablations (maximum power of 80–120 W for 240 s–480 s) and 12 to 16 radiofrequency ablations (180 s–240 s) in the main renal artery in a paired fashion, alternating the side of treatment, euthanized at 2 weeks (acute N=15) or 5.5 months (chronic N=15), and compared with undenervated controls (N=4). Microwave RDN produced substantial circumferential perivascular injury compared with radiofrequency at both 2 weeks [area 239.8 (interquartile range [IQR] 152.0–343.4) mm2 versus 50.1 (IQR, 32.0–74.6) mm2, P