Symplicity HTN-2 trial critiqued

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The results from the Symplicity trial, a multicentre randomised trial which enrolled patients with treatment resistant essential hypertension, showed that catheter-based renal denervation resulted in significant reductions in blood pressure. Iris Baumgartner, angiologist, Bern, Switzerland, critiqued the trial at the annual LINC meeting, Leipzig, Germany.

 

“It is hard to criticise good science, but I am going to try. The trial demonstrates for the first time in humans that renal sympathetic denervation can reduce blood pressure in a safe way and that results are sustained long-term (24 months). However, several concerns remain and must be explored,” she said.

 

Blood pressure

 

Going to the primary endpoint, the office blood pressure change was -32mmHg vs. +1mmHg at six months (p

 

A second concern was whether the patient group enrolled had blood pressure that was truly resistant. “Although salt restriction and spironolactone treatment are effective in resistant hypertension, only 17% of participants received an aldosterone antagonist. So was it a truly resistant patient population that was treated?

 

“Only 20% of the patients who received renal sympathetic denervation had medication dose decreased,” she noted.

 

Renal arteries

 

“When it comes to the anatomy, there might be some potential radiofrequency-induced tissue damage that will accelerate atherosclerosis in the injury points. What is the long-term damage from this?” asked Baumgartner.

 

She also brought up the issue of anatomical problems such as the existence of multiple renal arteries. “In such cases, are all renal arteries to be treated?” she asked.

 

Other issues

 

Baumgartner noted that renal sympathetic efferent nerves may re-grow after injury raising the possibility of finite time limits on the physiological effects of the procedure. “We need a longer-term follow-up to assess this aspect,” Baumgartner said.

 

With regard to the indications, she noted that predictors of blood pressure response have not yet been identified. “We have the data on resistant severe hypertension. Can the results of this study be generalised to a larger hypertensive population?

 

“The cost-effectiveness also needs to be examined, if renal sympathetic denervation is to be performed in milder forms of hypertensions and consequently in larger numbers of patients,” she said.

 

Baumgartner added that chronic renal disease was associated with sympathetic overactivity, and said patients with renal failure may be appropriate candidates for renal sympathetic denervation.

 

“If renal denervation is performed early in the process of disease, it might prevent development of target organ damage and detrimental consequences of hypertension. But we do not know yet, we do not have these endpoint,” said Baumgartner.

 

“The interventional renal denervation approach may offer the opportunity of a build-in therapy with benefits throughout patients’ lifetimes,” she concluded.

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