Renal Denervation Response Similar Regardless of CV Risks, Comorbidities

Debra L. Beck

June 15, 2020

In a new analysis of international registry data, blood pressures were reduced similarly in patients with varying high-risk comorbidities and across a range of cardiovascular risk scores.

At 3 years, 24-hour systolic BP was reduced by an average of –8.9 mm Hg overall, with slightly higher or lower readings seen in those with higher cardiovascular risk scores (–10.4 mm Hg) and 65 years or older (–10.2 mm Hg). Similar reductions were seen in those with resistant hypertension (–8.7 mm Hg), diabetes (–8.6 mm Hg), isolated systolic hypertension (–10.1 mm Hg), chronic kidney disease (–10.1 mm Hg), or atrial fibrillation (–10.0 mm Hg).

"In the largest international registry of its kind, the efficacy of renal denervation was similar in patients with and without baseline conditions associated with increased sympathetic activity and irrespective of ASCVD [atherosclerotic cardiovascular disease] risk," first author Felix Mahfoud, MD, said in an interview.

Dr. Mahfoud, from University Hospital of Saarland, Homburg, Germany, and colleagues published their analysis in the Journal of the American College of Cardiology.

The article reported a post hoc analysis of data from the Global SYMPLICITY Registry (GSR), an international, Medtronic-funded effort that includes 2,652 patients with uncontrolled hypertension treated with a Symplicity denervation system. Data were obtained from 196 centers in 45 countries.

"Blood pressure reductions were durable and sustained to 3 years and the rates of new-onset, end-stage renal disease and elevation in serum creatinine levels were very low in patients at high and low [cardiovascular] risk," reported Dr. Mahfoud.

As expected, adverse event rates were higher for patients with higher baseline cardiovascular risk. "Elevated rates were also seen in patients with [atrial fibrillation] and diabetes, identifying these subgroups who might derive even greater clinical benefit from improved BP control using renal denervation," said Dr. Mahfoud.

Asked which patients might be optimal candidates for renal denervation, Dr. Mahfoud recommended the technology for "patients with uncontrolled hypertension on medication, patients with nonadherence, unwillingness, or intolerability to medication, and patients with combined systolic and diastolic hypertension."

Analyses Limited by Incomplete Data

Stephen C. Textor, MD, has concerns over the amount of missing data in the GSR database and its continued use as a repository of information on renal denervation.

"I am a bit lukewarm on this paper in part because of the nature of the registry data they're using," he added in an interview. "The problem I see is that the registry is not terribly uniform as to what information they collect on each patient, not terribly uniform in terms of how the procedure is performed, and not terribly uniform on how they follow up patients."

Indeed, the post hoc subgroup analyses represent only a limited subset because of incomplete data, added Dr. Textor, a nephrologist at the Cleveland Clinic in Rochester, Minn.

"Remarkably, only 504 [patients] had "matched" data for office [systolic BP] levels at the time points defined in the report," he wrote in an editorial comment accompanying the registry report (J Am Coll Cardiol. 2020 Jun 16;75[23]:2889-91).

Similarly, the researchers were able to calculate baseline atherosclerotic cardiovascular risk scores in only 1,485 patients (56% of total), primarily because of missing cholesterol measurements.

"They simply did these paired comparison that may have included a couple hundred cases, and on average, there were no differences in response, but what I would have liked to see is a multivariate analysis, where you have all the data on everybody and look at what are the factors that impact response?" Dr. Textor said in the interview.

"They really couldn't do that because they just, they're just too many holes in the data," he added.

On the bright side, Dr. Textor noted that, while the impact overall on systolic BP was "modest," the standard deviations in some cases were large, indicating that some people had large reductions of systolic BP of more than 30-40 mm Hg.

"There is a belief out there that there are some people that really benefit from this, but how to identify them has been the question," Dr. Textor said.

Enthusiasm for renal denervation plummeted after results from the SYMPLICITY HTN-3 showed the procedure failing to meet its efficacy endpoint in resistant hypertension. The procedure was associated with a 14–mm Hg fall in systolic BP, compared with an 11–mm Hg drop in the "sham" control group (N Engl J Med. 2014 Apr 10;370:1393-401). However, post hoc analysis of the trial revealed significant shortcomings in design and execution.

No renal denervation device is approved in the United States. The Symplicity device used in this registry is approved in the European Union.

In early 2020, the Food and Drug Administration promised a rigorous review of new renal denervation trials. Subsequently, primary results from the SPYRAL HTN-OFF MED pivotal trial were presented at the annual meeting of the American College of Cardiology in March and showed promising efficacy.

SPYRAL HTN OFF-MED was designed in collaboration with the FDA to obtain meaningful evidence of whether renal denervation performed with the Symplicity Spyral multielectrode catheter (Medtronic Vascular) could reduce BP in patients not taking antihypertensive medication.

Dr. Mahfoud reported he has received speaking honoraria from Medtronic and ReCor. Two other authors are employees of Medtronic. Dr. Textor reported no relationships relevant to the contents of this paper. The Global SYMPLICITY Registry is funded by Medtronic Vascular.

SOURCE: Mahfoud F et al. J Am Coll Cardiol. 2020 June 16;75:2879-88.

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