SYMPLICITY TRIAL, HTM-3: Renal Denervation in Patients With Uncontrolled Hypertension

Bilateral renal denervation was performed using the Symplicity Catheter – a percutaneous system that delivers radiofrequency (RF) energy through the luminal surface of the renal artery.
SYMPLICITY HTN-3 differed from prior studies of renal denervation in that it had a sham-control group (renal angiography alone). The trial randomized 535 patients with resistant hypertension and all patients had a systolic blood pressure > 160 mm Hg in the office despite taking maximally tolerated doses of at least three anti-hypertensives, including a diuretic (five anti-hypertensives in average).
Although renal denervation with Symplicity catheter was safe (primary end-point), it did not provide a significant advantage over a sham procedure (control group) for reducing office blood pressure in the study.
Through 6 months of follow up, office systolic blood pressure dropped by 14.13 mm Hg in the denervation group and by 11.74 mm Hg in the control group. The difference between both groups was not statistically significant (2.39 mm Hg, P=0.26).
The reduction in average 24-hour ambulatory blood pressure in the denervation versus the sham-control group was also non-significant (only 1.96 mm Hg; 6.75 vs. 4.79 mm Hg, P=0.98).
The study also revealed no differences between the groups in the occurrence of major adverse events.
The failure of the trial was not surprising as Deepak Bhatt and collaborators stated, pointing out a meta-analysis published last year that predicted that carefully conducted, randomized studies of renal denervation would fail to show the dramatic reductions in blood pressure observed in un-blinded and uncontrolled previous studies.
“Further study in rigorously design clinical trials will be necessary to confirm previously reported benefits of renal denervation in patients with resistant hypertension or to validate alternate methods of renal artery denervation” Bhatt indicated during his presentation.
According to the authors, the trial addressed some potential limitations, including the relatively short follow-up, the possible influence of operators who were inexperienced with renal denervation, and the lack of a direct measurement of whether the renal arteries were genuinely denervated.
Despite the results of Symplicity HTN study, Bhatt said that he still remains “cautiously optimistic” about renal denervation’s chances and insist with by “future investigations the first step has got to be to make sure we are actually denervating on a biological level.”

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