Why is this study important? 

• Long term three-year follow up of the largest randomized controlled renal denervation (RDN) study for control of hypertension.
• RDN is a suitable additive therapy in lowering blood pressure (BP) in selected patients with resistant hypertension (HTN) on multiple drug therapy.

What question was this study supposed to answer? 

• Is RDN beneficial in resistant HTN? 
• Is there a sustained reduction in systolic and diastolic BP in those with resistant hypertension on three or more antihypertensive drugs after invasive Radiofrequency (RF) RDN using first generation Symplicity Flex™ catheter (Medtronic corporation, Minneapolis, MN)? 

What did the study show? 

• Patients with resistant HTN Office SBP ≥160 mm Hg or 24hr ABPM ≥135 mm Hg on maximally tolerated dose of ≥3 anti-HTN medications were included in the study.
• This was a 2: 1 randomized, sham-controlled, blinded trial at 88 US sites, with 364 patients in RDN arm and 171 in sham control arm.
• No changes were allowed in anti-hypertensive therapy for 6 months.
• Baseline blood pressure in the group of patients who ultimately comprised the sham control and did not cross over had a much lower baseline systolic blood pressure and would have likely not had a comparable blood pressure reduction.  
• Crossover was allowed to RDN at 6 months in the sham control arm.
• At 36 months the magnitude of BP reduction was greater than the first 12 or 24 months with average reduction of systolic BP by 22 mm Hg (P < 0.0001) and diastolic BP by 12 mm Hg (P < 0.0001)-this benefit was at 4.5 years.
• There were no long-term complications related to RDN.

All editors: S. Tanveer Rab, MD, FSCAI