SYMPLICITY FLEX Studies Renal Denervation for Mild Refractory Hypertension

September 16, 2014—At the 26th annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium in Washington, DC, results from the SYMPLICITY FLEX trial were presented and showed that renal sympathetic denervation (RSD) to treat mild refractory hypertension was associated with reductions in blood pressure in secondary analyses, but missed its primary endpoint.

As summarized in the TCT press release, the small-to-modest sized but sham-controlled SYMPLICITY FLEX trial randomized a total of 71 patients with refractory hypertension and mildly elevated blood pressure (daytime systolic blood pressure [BP] of 135–149 and/or diastolic blood pressure of 90–94 mm HG on ambulatory BP measurement). One group received catheter-based RSD, whereas the second group received an invasive sham procedure. All patients had a stable antihypertensive drug regimen of three or more agents, including a diuretic, except when not tolerated or contraindicated. The primary endpoint was the change in 24-hour systolic blood pressure at 6 months. 

The mean change in 24-hour systolic BP in the intention to treat cohort at 6 months was -7 ± 10.6 mm Hg for patients undergoing RSD and -3.5 ± 9.4 mm Hg in the sham group (P = .15). In the per-protocol population, the change in 24-hour systolic BP at 6 months was -8.3 ± 8.9 mm HG in the RSD group compared to -3.5 ± 9.5 mm HG in the sham group (P = .042). 

There was also a significant reduction in daytime systolic BP in RSD patients in the per-protocol analysis (-9.9 ± 9 vs. -3.7 ± 9.9; P = .012). No significant changes in the 24-hour diastolic, mean BP, or any measures of nighttime BP were recorded, and there were no serious adverse events, advised the TCT announcement.

In the TCT press release, SYMPLICITY FLEX Lead Investigator Steffen Desch, MD, commented, “In patients with mild refractory hypertension, renal sympathetic denervation showed a significant reduction of 24-hour systolic BP in the per-protocol cohort at 6 months, however in the intention to treat population, the results were not significant. Findings indicate that this procedure could supplement current therapies and help reduce the number of patients with uncontrolled high blood pressure.” Dr. Desch is with the University of Schleswig-Holstein, Campus Lübeck in Germany.