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BOSTON -- Pulmonary artery denervation improved symptoms in pulmonary arterial hypertension (PAH), a clinical trial from China showed.

The radiofrequency ablation procedure increased 6-minute walk distance by 33.8 m more from baseline to 6 months compared with a sham procedure (P<0.001), reported Shao-Liang Chen, MD, PhD, of Nanjing First Hospital of Nanjing Medical University in China, during the Transcatheter Cardiovascular Therapeutics (TCT) meeting hosted by the Cardiovascular Research Foundation.

Denervation also improved hemodynamics and reduced clinical worsening, his group noted in a paper published simultaneously in .

The trial used an investigational ablation catheter designed specifically for use in the pulmonary artery, which is a "challenging" space to work in with anatomical variances, noted session panelist Eric A. Secemsky, MD, of Beth Israel Deaconess Medical Center in Boston.

Chen noted there were no major severe intraprocedure complications with the 10-electrode device, deployed for 2 minutes at each of the typically three ablation sites without sedation.

Following on the heels of renal artery denervation for hypertension, Chen's device is one of several attempting to tackle PAH by silencing the baroreceptors and sympathetic nerve fibers localized in or near the bifurcation area of the main pulmonary artery.

"It opens the field of multiorgan denervation, so denervating not only the kidneys but also other organs that are innervated by the sympathetic nervous system, including the lungs," said TCT press conference panelist Felix Mahfoud, MD, of Saarland University Medical Center in Homburg, Germany.

Fellow panelist Riyaz Bashir, MD, of Temple University in Philadelphia, said he was "very encouraged by the results of this smaller but really well-done study. ... Technically I think it is feasible, but we need more data."

Chen acknowledged that a larger trial will be needed and noted that his group is planning a global trial with a different clinical endpoint and use of combination medication therapy in the background regimen.

His group's with the pulmonary artery denervation catheter he invented had included 21 idiopathic PAH patients with insufficient response to combination therapy using at least two drugs after an average of 3.3 years of use.

The current trial included 128 patients ages 18 to 70 who had PAH classified as WHO Group I (not due to left heart disease, lung disease, or chronic thromboembolism) and were not taking PAH-specific drugs for at least the prior 30 days, other than diuretics or antithrombotic agents. They were randomly assigned to pulmonary artery denervation plus post-procedure titrated medical therapy with a phosphodiesterase-5 inhibitor or a sham procedure plus that titrated medical therapy.

PAH was confirmed by right heart catheterization with a negative acute vasoreactivity test. Patients were followed for 6 months.

Secondary findings included a significant improvement in pulmonary vascular resistance from baseline to 6 months by 1.4 Wood units more after denervation than sham, with relative reductions to that point of 27% versus 15% (P=0.003). Right ventricular function, tricuspid regurgitation, and cardiac injury marker NT-proBNP were also significantly better with the procedure than sham.

Clinical worsening occurred in 1.6% of denervation patients compared with 13.8% of sham cases (OR 0.11, 95% CI 0.01-0.87). Satisfactory clinical response based on a combination of increasing exercise capacity, improving functional class, and decreasing NT-proBNP levels occurred in 57.1% versus 32.3% (OR 2.79, 95% CI 1.37-5.82).

The 6-minute walk distance gains with denervation weren't outstanding compared with those of combination medical therapy in the AMBITION trial (about a 20-m gain versus monotherapy) or of balloon pulmonary angioplasty (about a 70-m gain).

It "may be an adjunct," suggested Roxana Mehran, MD, of Mount Sinai School of Medicine in New York City. "The window is open for renal denervation, and certainly we will see ... about pulmonary artery denervation."

One note of caution was raised by Ori Ben-Yehuda, MD, of the CRF Clinical Trials Center in New York City, who was involved in a prior pulmonary artery denervation trial with a different device. "In the , we did see some decrease in efficacy using an ultrasound-based catheter after 6 months, so this is an important long-term issue."

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