Symplicity Flex: No Benefit of Renal Denervation in Mild Resistant Hypertension

In a small study of patients with mild refractory hypertension, renal denervation did not reduce 24-hour systolic BP at 6 months compared with an invasive sham procedure, although a reduction was seen in per-protocol analysis, according to late-breaking clinical trial results presented at TCT 2014.

tues.desch.headSteffen Desch, MD, of the University of Schleswig-Holstein, Lübeck, Germany, and colleagues performed the randomized trial, which included patients with average daytime ambulatory BP readings of 135 mm Hg to 149 mm Hg systolic and/or 90 to 94 mm Hg diastolic at baseline, despite treatment with at least three antihypertensive medications of different classes, including a diuretic. Patients were randomly assigned to renal denervation with the Symplicity Flex catheter (Medtronic; n=35) or an invasive sham procedure (n=36). Patients and their physicians were asked to not change medication regimens during the 6-month study period.

The average ambulatory systolic pressure readings were 144.4 mm Hg in the renal denervation arm and 143 mm Hg in the sham-control arm, and the average number of antihypertensive agents being taken was 4.4 and 4.3, respectively. Both BP and the number of medications were lower than seen in prior trials of renal denervation for more severe resistant hypertension, Desch noted.

Cautious interpretation

In the main intention-to-treat analysis, there was a nonsignificant reduction in ambulatory systolic BP at 6 months — the primary endpoint — with renal denervation (see Figure). It became significant, however, in a per-protocol analysis excluding four patients — two who had incomplete renal denervation procedures with only one or two ablation runs, one who did not undergo the sham procedure as planned, and one who had preexisting renal artery stenosis that was not identified at baseline. tues.desch.figure

During a panel discussion, Ajay J. Kirtane, MD, SM, of Columbia University Medical Center, New York, N.Y., urged caution in interpreting the per-protocol analysis because it excluded some patients who underwent treatment after randomization and who would usually be included in such an analysis.

Deepak L. Bhatt, MD, MPH, of Brigham and Women’s Hospital, Boston, Mass., said the study was well done and credited the investigators for using a sham control, but raised some additional concerns, including the small sample size and the fact that the effect size in the per-protocol analysis was modest. “I think this adds to the field where there are positive signals for this therapy but certainly not conclusive evidence,” Bhatt said.

 

Disclosures:

 

  • Desch reports no relevant conflicts of interest.

  • Bhatt reports relationships with multiple device and pharmaceutical companies.

  • Kirtane reports relationships with multiple device companies.

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