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Symplicity Works: Renal Denervation Reduces Resistant Hypertension

By Yael L. Maxwell

CHICAGO, IL— For patients with refractory hypertension, catheter-based renal denervation by radiofrequency (RF) ablation continues to result in safe and durable blood pressure reductions without serious adverse events, according to 2 separate presentations March 25, 2012, at the annual American College of Cardiology (ACC)/i2 Scientific Session.

For the first study, Paul A. Sobotka, MD, of the Ohio State University (Columbus, OH), presented 3-year data from the Symplicity HTN-1 trial. Initially presented March 2009 at the annual ACC meeting and simultaneously published in the Lancet, the results showed substantial and sustained blood pressure reductions after renal denervation in 70 patients from 5 Australian and European centers who had an office-based systolic BP ≥ 160 mm Hg despite being on 3 or more antihypertensive drugs, including a diuretic. There were no significant vascular or renal complications and no decline in kidney function at 1 year.

The cohort was since expanded to include 153 patients from 19 sites in the United States, Europe, and Australia, with follow-up out to 3 years. On average, baseline blood pressure was 175 mm Hg and patients were on 5 antihypertensive drugs, including a diuretic.

Simply Success

One hundred percent of patients were considered responders, defined as experiencing a ≥ 10 mm Hg reduction in systolic blood pressure at 3 years, including each of the 45 late responders, who did not originally respond at 1 month. Follow-up office-based assessment showed significant reductions in both systolic and diastolic blood pressure beginning at 1 month, which were sustained at 6-month intervals through 3 years (P < 0.01 for all time points).

Patients who crossed over to renal denervation after initially being treated with pharmacologic therapy also saw substantial blood pressure reductions at 1 year.

The procedure was considered safe with no significant changes in renal function at 3 years. However, there was 1 progression of pre-existing stenosis unrelated to the current treatment and 1 moderate stenosis that was not hemodynamically relevant. Three unrelated deaths were observed, but no major complications.

In response to the question of known mechanisms that may explain the durability of the intervention, Dr. Sobotka said that while kidney neurologic function was not studied, “the response in blood pressure is so significant, it’s hard to imagine that something in the neurologic memory is reformed that has any clinical importance.”

The Sooner the Better with Denervation

Murray D. Esler, MD, of the Baker IDI Heart and Diabetes Institute (Melbourne, Australia), presented 1-year results from the international, multicenter, prospective Symplicity HTN-2 trial. Six-month results, which showed substantial blood pressure decreases in a small, randomized cohort of patients after renal denervation, were presented November 2010 at the American Heart Association Scientific Sessions and simultaneously published in the Lancet. Dr. Esler’s presentation specifically focused on 35 of the 54 patients originally assigned to the control group who were allowed to cross over to treatment at 6 months.

Patients who crossed over saw substantial reductions in blood pressure similar to those of patients who originally received treatment (-23.7 ± 27.5 mm Hg systolic; P < 0001 vs. baseline; -8.4 ± 12.1 mm Hg diastolic; P < 0.001 vs. baseline). Long-term safety was established with no deaths and only 3 hypertensive events reported in 2 crossover patients.

“There may be significant costs associated with delaying denervation,” Dr. Esler said. “These patients were treated with 6 months of medication that was essentially ineffective.”

Study Details

Using femoral access, an RF-tipped catheter (Ardian, Palo Alto, CA) was inserted into the renal arteries. RF energy was applied to the nerve for up to 2 minutes; then the catheter was withdrawn slightly and rotated circumferentially and another energy dose was applied. The process was repeated 4 to 6 times in each kidney.

 

 

 

Sources:1. Sobotka P. Long-term follow-up of catheter-based renal sympathetic denervation for resistant hypertension confirms durable blood pressure reduction. Presented at: American College of Cardiology Scientific Session; March 25, 2012; Chicago, IL.

 

2. Esler MD. Renal sympathetic denervation for treatment of resistant hypertension: One-year results from the Symplicity HTN-2 randomized controlled trial. Presented at: American College of Cardiology Scientific Session; March 25, 2012; Chicago, IL.

Disclosures:

  • Dr. Sobotka reports being an employee of Medtronic.
  • Dr. Esler reports receiving research support from and consulting for Ardian Inc. and Medtronic.

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Renovascular