Study procedures
The four-electrode radiofrequency Symplicity Spyral catheter and the Symplicity G3 radio frequency generator (Medtronic; Minneapolis, MN, USA) were used to produce ablations in a spiral pattern in the main renal arteries, accessory, and branch vessels between 3 and 8 mm in diameter. Eligible patients randomized to the sham procedure remained on the procedure table for at least 20 min following the renal angiogram to ensure blinding. Before initiating 24 h ambulatory blood pressure monitoring at 3, 6, 12, 24, and 36 months (Mobil-O-Graph; IEM; Stolberg, Germany), all subjects ingested prescribed antihypertensive medications in the presence of staff. Antihypertensive medications changes were allowed after the primary 6 months follow up by physician discretion. The study was originally designed to only collect urine and blood tests at baseline and 6 months and, in some patients, at 24 and 36 months following a study protocol update. Duplex ultrasound, CT, or MRI was recommended to be performed either at 12, 24, or 36 months to assess renal artery anatomy. Patients in the sham control group were eligible for crossover to receive the RDN procedure after their 12-month follow-up visit according to patient and investigator discretion.