Renal denervation can treat hypertension without drugs: study

Second-generation renal denervation (RDN), using high-frequency sound waves, can lower blood pressure significantly and consistently with excellent safety in patients with intractable hypertension that is difficult to treat with antihypertensive drugs, local researchers said in a study.

RDN could be an even more attractive treatment strategy for Asian patients who are sensitive to sympathetic modulation, the study said.

Blood pressure changes with second-generation RDN devices in recently published randomized, sham-controlled trials. (Source: Korean Circulation Journal)

Professors Choi Seung-hyuk and Choi Ki-hong of cardiology at the Samsung Medical Center published the paper in the September issue of Korean Circulation Journal. The journal’s editor introduced the study in the “State of the Art Review.”

In the study, titled “Current Status and Future Perspectives of Renal Denervation,” the researchers reviewed the second-generation RDN’s efficacy and safety based on randomized controlled clinical trials of RDN that demonstrated therapeutic effect in drug-resistant hypertension. They also suggested possibilities and challenges of expanding it to cardiovascular disease treatment.

The researchers introduced Medtronic’s second-generation RND device, SYMPLICITY Spyral, and ReCor Medical’s balloon-type ultrasonic RDN catheter. The two products proved efficacy and safety through comparative trials, respectively.

Also, the research team presented results from a single-blind trial that directly compared the blood pressure-lowering effect between radiofrequency ablation-based DRN and ultrasound-based RDN. The results showed that patients treated with ultrasound-based RDN had more reduction (6.5 mmHg reduction on average) in weekly ambulatory systolic blood pressure (ABP) than those who received radiofrequency ablation-based DRN.

“This result might be because ultrasound energy has deeper penetration and offers complete renal nerve ablation of the main renal artery than the RF ablation of the main renal artery alone,” the research team said.

Nevertheless, this result should be interpreted with caution due to the limitations of this study, including the lack of a sham-control, lack of information about drug adherence tracking, and small sample size, it added.

Unlike antihypertensive medications, the safety of RDN in hypertension patients focuses on procedural complications, the researchers went on to say. After the RDN procedure, the most anticipated complications included renal artery injury, vascular access site complications, and deterioration in kidney function. However, the safety profile of RDN in several registries and clinical trials appeared to be excellent.

A meta-analysis of 50 published RDN trials showed that only 26 out of (0.45 percent) of 5,769 patients with 10,249 patient-years of follow-up were found to have renal artery stenosis or dissection.

The researchers said that the three-year safety data from the largest database, the open-label Global SIMPLICITY registry, showed an extremely low incidence of peri-procedural complications and adverse events.

The research team emphasized significant ethnic differences in the determinants of hypertension and the risk of hypertension-related cardiovascular disease and that RDN was an attractive blood pressure-lowering strategy for Asian patients.

According to the research team, the prevalence of hypertension in Asia is similar to that in other countries despite a lower prevalence of metabolic syndrome.

The association between blood pressure and cardiovascular disease, especially for hemorrhagic stroke and non-ischemic heart failure, is stronger in Asian patients than in their Western peers, they said.

“Masked hypertension (defined as normal office blood pressure and elevated out-of-office blood pressure), which is associated with increased sympathetic activity, is more prevalent in Asians than in Westerners,” the researchers said.

East Asian people, in particular, have at least a two-fold higher sensitivity to the β-blocking effects of propranolol than white populations, they explained.

“Taken together, these ethnic differences indicate that Asian populations might be particularly sensitive to sympathetic modulation, thereby making the RDN procedure an attractive BP-lowering strategy for Asian patients,” they said.

Future RDN trials should focus not only on blood pressure reduction but on “cardiovascular outcomes, adequate patient selection to show the greatest benefit, completeness of ablation without significant peri-procedural complications, and potential roles in treating other morbidities characterized by sympathetic overactivity,” the researchers said.

Also, evidence is needed for the benefits of second-generation RDN devices in Asian patients, they added.