New results provide support for renal denervation

Renal denervation may still have potential to treat resistant hypertension according to new findings from studies that included Australian centres.

While the controversial technique previously showed minimal benefit in the SYMPLICITY HTN-3 study, two new trials have shown significant benefits of renal denervation.

Published in the Lancet, results from the SPYRAL HTN-ON MED proof-of-concept study involving 80 patients with uncontrolled hypertension on antihypertensive medication showed that renal denervation was effective in reducing blood pressure at six months compared to a sham procedure.

The change in blood pressure was significantly greater at six months in the renal denervation group than the sham-control group for both 24 h ambulatory measures of systolic blood pressure (SBP −7·4 mm Hg) and diastolic blood pressure (DBP −4·1 mm Hg).

Patients enrolled in the  trial initially had a 24 h ambulatory SBP of between 140 mm Hg and 170 mm Hg and were on one to three antihypertensive drugs with stable doses for at least six weeks.

The study authors said it was notable that renal denervation extending into branch arteries was associated with significant and clinically relevant reductions in BP in patients who were on medication. They also highlighted the finding that the extent of blood pressure reduction with renal denervation increased over follow-up from three months through six months

“The short-term safety profile of the intervention is favourable with no major adverse events recorded,” they remarked.

The study also showed that adherence with antihypertensive medication was highly variable, with roughly half the patients not adherent to their prescribed antihypertensive medication regimen during the trial.

In a separate study, RADIANCE-HTN SOLO, the use of endovascular ultrasound renal denervation was shown to reduce ambulatory BP compared to a sham procedure in a trial of 146 patients with hypertension in the absence of antihypertensive medications.

After two months of follow up, the reduction in daytime ambulatory SBP was 6.3mmHg greater with renal denervation than the sham procedure.

A commentary co-authored by Professor Murray Esler of the  Baker Heart and Diabetes Institute, Melbourne, noted that the SYMPLICITY HTN-3 study had been criticised by some for not being rigorously executed “and … the renal denervation was suboptimal because of various technical issues related to the renal artery anatomy and technique for energy delivery.”

Their commentary added that “RADIANCE-HTN SOLO, together with the SPYRAL-OFF and ON MED trials … might provide the first true trial evidence that renal denervation lowers blood pressure.”

But given the variable responses seen between patients, the next challenge was to identify which patient subgroups would be responders and non-responders, and thus which patients would be likely to receive the most benefit from renal denervation, the commentary authors concluded.

“Future research also needs to confirm whether there is a sustained blood pressure lowering effect  … and whether the procedure is safe in the long term, beyond the initial 6 months.”

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