Meta-analysis: Renal Denervation Effective Regardless of Catheter Type

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In patients with resistant hypertension, renal denervation substantially reduces blood pressure at 6 months, with the benefit apparent as early as 3 months and sustained at 1 year, according to a meta-analysis published online May 8, 2013, ahead of print in the Journal of the American College of Cardiology. Results were consistent regardless of study design or catheter type used for the ablation procedure.

The findings were first presented at the American College of Cardiology/i2 Scientific Sessions in San Francisco in March 2013.

Dominique Joyal, MD, of McGill University (Montreal, Canada), and colleagues performed a systematic review and meta-analysis of 12 published studies on renal denervation in a total of 561 patients with resistant hypertension who were treated between 2008 and 2012. The meta-analysis included:

• 2 randomized controlled trials
• 1 observational study with a control group
• 9 observational studies without a control group

Five different catheter types were employed, and follow-up duration varied between 1 and 24 months (median of 6 months).

Consistent Reduction in Blood Pressure

In the controlled studies, renal denervation reduced mean levels of systolic and diastolic blood pressure at 3 and 6 months, an effect that persisted at 12 months. The same was true in the uncontrolled studies, although fewer of these studies had adequate follow-up (table 1).

Table 1. Mean Changes in Blood Pressure: Renal Denervation vs. Medical Therapy

Among the 5 catheter types, there was no evidence that any specific type was more effective than any other.

The pooled non-responder rate for renal denervation was 13.3%. No deaths were reported.

Renal Artery Changes Uncommon But Require More Study

“The short-to-intermediate term data suggest that [renal denervation] is safe and well tolerated, with the most common periprocedural complaint being abdominal pain that responds to sedatives and/or narcotics,” the study authors write. “The only complications identified in our review were pseudoaneurysms at the vascular access site in 4 subjects, and 1 case of renal artery dissection on initial placement of the catheter prior to delivery of the radiofrequency signal.”

Two published case reports, they add, have documented individual patients who initially responded to renal denervation but saw an increase in blood pressure on subsequent follow-up visits. In both instances, renal Doppler imaging and angiography demonstrated renal artery stenosis, which required renal artery stenting. The proportion of patients who may develop renovascular abnormalities after the treatment also is unknown.

Furthermore, Dr. Joyal and colleagues say that studies are needed “to evaluate long term changes in renal artery anatomy post [renal denervation] as well as determine the appropriate imaging follow-up.”

Reasonably Reassuring

In a telephone interview with TCTMD, Deepak L. Bhatt, MD, MPH, of Brigham and Women’s Hospital (Boston, MA), said the meta-analysis confirms that renal denervation “seems to work in terms of reducing blood pressure at least in the target population in which it is being used, which is patients with resistant hypertension.”

He added that the similar outcomes across study designs and catheter types “certainly confirms that there is a class effect” with renal denervation.

“That’s reassuring to me, and I would compare it to statins,” Dr. Bhatt said. “Once we saw that several statins were all [effective], it became irrefutable that statins across the board were reducing ischemic events. I think the same thing is true here. Data and evidence are building up, and it’s obvious that we’re onto something with renal denervation.”

But Dr. Bhatt, who is co-principal investigator for the randomized, blinded Symplicity HTN-3 trial, added that he believes that trial will provide the best assessment of the modality’s safety and efficacy.

“That trial will be important because although there have been several studies and now we have this meta-analysis, we don’t have level A evidence. These are good data—helpful data—but not gold standard data,” he said. “While they are encouraging, they may be overly optimistic of the effect size.”

Dr. Bhatt added that evidence to date suggests the procedure is durable to at least 3 years, with no signal that the effect is abating.

 

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Source:
Davis MI, Filion KB, Zhang D, et al. Effectiveness of renal denervation therapy for resistant hypertension: A systematic review and meta-analysis. J Am Coll Cardiol. 2013;Epub ahead of print.

 

• Dr. Bhatt reports receiving research grants from Amarin, AstraZeneca, Bristol-Myers Squibb, Eisai, Ethicon, Medtronic, Sanofi-Aventis, and The Medicines Company and serving as co-principal investigator for the Symplicity HTN-3 trial.

 

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