Medtronic's Symplicity HTN-2 1-Year Results Support Renal Denervation Therapy

December 18, 2012—Murray D. Esler, MD, et al published 1-year results from the Symplicity HTN-2 trial in Circulation (2012;126:2976–2982), concluding that renal denervation provides safe and sustained reduction of blood pressure to 1 year.

According to a press release from Medtronic, Inc. (Minneapolis, MN), the Symplicity HTN-2 trial is an international, multicenter, prospective, randomized, controlled study of the company's Symplicity renal denervation system in patients with treatment-resistant hypertension. 

The study randomly allocated 106 patients at 24 centers in a one-to-one ratio to undergo renal denervation as well as receive previous antihypertensive medication treatment or to maintain previous antihypertensive medication treatment alone (control group) at 24 participating centers. Patients in the control arm of the study were offered renal denervation after assessment of the trial's primary endpoint at 6 months following randomization.

Medtronic stated that the 1-year data showed that patients who initially received treatment with the Symplicity renal denervation system sustained a significant drop in blood pressure compared to baseline at 12 months, which demonstrates preservation of the benefit at 6-month follow-up. At 12 months, there were no reported device-related serious adverse events, no late vascular complications, and no significant decline in kidney function. The investigators also reported the results of 35 patients in the control group who received renal denervation after the primary endpoint was assessed at 6 months. This crossover group showed a significant drop in blood pressure 6 months after the renal denervation procedure. This decrease in blood pressure is similar to the blood pressure reduction in the initial treatment arm at 6 months, the company noted.

As detailed in Circulation, the Symplicity HTN-2 trial enrolled eligible patients who were on three or more antihypertensive drugs and had a baseline systolic blood pressure ≥ 160 mm Hg (≥ 150 mm Hg for type 2 diabetics). Renal denervation in control patients was permitted after the 6-month primary endpoint was met.

At 12 months after the procedure, the mean fall in office systolic blood pressure in the initial renal denervation group (−28.1 mm Hg; 95% confidence interval, −35.4 to −20.7; P < .001) was similar to the 6-month fall (−31.7 mm Hg; 95% confidence interval, −38.3 to −25; P = .16 vs 6-month change). The mean systolic blood pressure of the crossover group 6 months after the procedure was significantly lowered (from 190.0 ± 19.6 to 166.3 ± 24.7 mm Hg; change, −23.7 ± 27.5; P < .001). In the crossover group, there was one renal artery dissection during guide catheter insertion, before denervation, that was corrected by renal artery stenting, and one hypotensive episode, which was resolved with medication adjustment, reported the investigators in Circulation.

Dr. Esler, who is Principal Investigator of the Symplicity HTN-2 trial and Senior Director of the Baker IDI Heart and Diabetes Institute of Melbourne, Australia, commented about the findings in Medtronic's press release. He stated, “We continue to see positive results from the Symplicity HTN-2 clinical trial, demonstrating consistent, long-term blood pressure reduction with the Symplicity system in patients with treatment-resistant hypertension, who have a three-fold increase in risk of cardiovascular events. These data further substantiate the clinical benefits of renal denervation with Symplicity over longer periods of time in this difficult-to-treat patient group.”

Medtronic advised that the Symplicity renal denervation system is not approved by the US Food and Drug Administration for commercial distribution in the United States.