Renal Denervation in the treatment of Resistant Hypertension

Hypertension is a risk factor for coronary artery disease and stroke. Only about half of the patients with hypertension are adequately controlled on medical therapy, and about a quarter may develop severe or resistant hypertension. Resistant hypertension is defined as failure to achieve target blood pressure of <140/90mmHg while on full doses of an appropriate three-drug regimen that includes a diuretic. Increasingly more attention has been paid to the potential of renal denervation (RDN) as treatment for resistant hypertension, guided by a better understanding of renal nerve anatomy. RDN is undergoing transformation as a technology for the treatment of resistant hypertension. Early studies demonstrated efficacy in treating resistant hypertension patients with significant reduction in office blood pressure (BP). However, the randomised sham-controlled trial, Symplicity HTN-3, did not demonstrate any significant difference in BP reduction between the RDN and the sham control arm. Since then, further improvements have been made in developing second generation systems. Subsequent studies showed the importance of more distal and branch renal artery ablation, and multielectrode systems have been utilised. Two randomised shamcontrolled trials, the SPYRAL HTN-OFF MED and SPYRAL HTN-ON MED studies showed the effectiveness of RDN with the second-generation radiofrequency ablation system. These studies showed that RDN significantly reduced office and 24-hour ambulatory BP when compared with sham control treatment. The RADIANCE-HTN SOLO trial also demonstrated efficacy using an ultrasound-based catheter system for RDN treatment of resistant hypertension. These trials have reinvigorated current clinical interest in RDN as treatment for resistant hypertension. There is increasing evidence for RDN as an effective treatment for uncontrolled or resistant hypertension. The RDN procedure has also evolved with time, with an improved practice of delivering a larger number of ablations to distal vessels in addition to main renal arteries. The RDN procedure has a low complication rate and may provide an approach that could potentially reduce the morbidity and mortality risks associated with resistant hypertension in Malaysia.