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SYMPLICITY HTN-2: Renal Denervation Safe, Effective at 3 Years

By Yael L. Maxwell

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Three-year findings from the SYMPLICITY HTN-2 trial once again swing the pendulum of support back to the side of renal denervation, showing sustained decreases in blood pressure (BP) in select patients with severe, treatment-resistant hypertension. The paper, published online June 4, 2014, ahead of print in the European Heart Journal, cautions that proper patient selection and operator training are key to procedural success.

SYMPLICITY HTN-2 is “relatively small,” but unlike SYMPLICITY HTN-3 it was conducted only at centers where all participating operators had prior hands-on experience, Murray D. Esler, MD, of the Baker IDI Heart and Diabetes Institute (Melbourne, Australia), and colleagues say. The “flaw in the design of SYMPLICITY HTN-3,” they write, “was likely based on the notion that renal denervation is easily achieved, which it is not.”

Methods
For SYMPLICITY HTN-2, 106 patients with treatment-resistant hypertension were randomized to medical management with or without renal denervation with the Symplicity Catheter System (Medtronic; Minneapolis, MN). A small cohort originally assigned to medical management alone (n = 37) was allowed to cross over to treatment at 6 months. Two-year results, presented at the 2013 American Heart Association Scientific Sessions in Dallas, TX, demonstrated substantial BP reductions in both the initial and crossover renal denervation groups.
Baseline BP for all treated subjects combined was 184 ± 19/99 ± 16 mmHg. The crossover group had more women and higher baseline eGFR and office systolic BP. Most subjects received a diuretic, beta-adrenergic blocker, calcium channel blocker, and an angiotensin receptor blocker or ACE inhibitor.


SYMPLICITY Works Yet Again

Follow-up at 3 years was available for 76.9% of the initial and 81.1% of the crossover renal denervation groups. Systolic and diastolic BP measurements were lower than the preprocedural measurements at 6, 12, 24, 30, and 36 months (P < .01 for all).

For the 69 patients with 30-month post-procedure follow-up, the change in systolic BP was -34 mmHg (95% CI -40 to -27 mmHg; P < .01) and the change in diastolic BP was -13 mmHg (95% CI -16 to -10 mmHg; P < .01). The systolic and diastolic BP reductions at 36 months in the initial renal denervation group was 33 mmHg (95% CI -40 to-25 mmHg; P < .01) and 14 mmHg (95% CI -17 to -10 mmHg;  P < .01), respectively. Both initial and crossover patients had similar reductions in systolic BP at 30 months (-34 ± 23 vs -33 ± 33 mmHg, respectively).

Additionally, heart rate slowed following renal denervation and this decrease was maintained at 36 months with a mean decrease of 4 bpm (95% CI -8 to -0.1 bpm; P = .04).

At 36-month follow-up, patients treated with renal denervation were prescribed fewer  antihypertensive medications compared with baseline (4.6 ± 1.6 vs 5.1 ± 1.5; P = .02) due in part to significantly lower usage of angiotensin converting enzyme (ACE) inhibitors and centrally acting sympatholytics.

The Case for Proper Protocol, Patient Selection

“Our similar results confirm the substantial magnitude and long-term durability and safety of the [renal denervation] antihypertensive effects,” the authors observe.

“While results in SYMPLICITY HTN-2 were consistent with results in SYMPLICITY HTN-1 and other reports with the Symplicity catheter, results in SYMPLICITY HTN-3 have been inconsistent to previous studies,” they note, adding that the latter study may have involved inadequate denervation and enrolled patients who had not exhausted all treatment options.

Even so, renal denervation “should only be considered after careful clinical evaluation to eliminate both white-coat hypertension (using 24-hour ambulatory blood pressure monitoring) and secondary causes of hypertension (primary aldosteronism being most likely to remain unidentified), and after pharmacological and other nonpharmacological treatment options have been optimally applied,” Dr. Esler and colleagues caution.

 

Source:
Esler MD, Bӧhm M, Sievert H, et al. Catheter-based renal denervation for treatment of patients with treatment-resistant hypertension: 36 month results from the SYMPLICITY HTN-2 randomized clinical trial. Eur Heart J. 2014;Epub ahead of print.

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Disclosures
  • SYMPLICITY HTN-2 was sponsored by Medtronic.
  • Dr. Esler reports no relevant conflicts of interest.

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