Now that SYMPLICITY HTN-3 has provided a reality check, the necessary next steps include improving the technology. Current levels of achieved RDN using only proximal ablation are suboptimal. What’s needed are higher-energy, multipolar electrodes that deliver energy both proximally and distally; such equipment is well along in development.
A thornier limitation involves the lack of a method for immediate testing of the completeness of an RDN procedure in a given patient. Unlike in coronary stent placement, where an interventional cardiologist can immediately see angiographically whether the device is properly seated, RDN operators have no way to tell intraprocedurally whether effective RDN has been achieved. Two methods now under investigation are intra-arterial adenosine and urinary biomarkers of nerve degradation.
The pathophysiology of hypertension is variable, so efforts are underway to identify patient subsets in which sympathetic nervous system overactivity is a primary underlying mechanism and RDN should have its greatest impact.
“I think renal denervation is still worthy of investigation, particularly in patients with resistant hypertension and perhaps other disease states characterized by sympathetic overactivity, such as heart failure,” Dr. Gersh concluded. “How do I think it’s going to all turn out? I just don’t know. We’ll see. We need the trials. I don’t think we should close the book on this very exciting technique. I simply don’t know what the trials are going to show.”
SYMPLICITY HTN-3 was funded by Medtronic. Dr. Gersh reported serving as a consultant to Merck and Ortho-McNeil-Janssen and on data safety monitoring boards for trials sponsored by Baxter, Medtronic, and Teva Pharmaceuticals.