Renal sympathetic denervation
The other approach to controlling BP, described at the same session, consists of disrupting renal sympathetic nerves, an approach long considered an attractive therapeutic target for hypertension but which previously required invasive surgery, according to Henry Krum, MD, PhD, of the Centre of Cardiovascular Research and Education in Therapeutics at Monash University in Melbourne, Australia. “Therefore, we are taking a simplified radiofrequency ablation approach to renal sympathetic denervation,” Dr. Krum said.
Dr. Krum presented findings from a 12-month evaluation of percutaneous renal sympathetic denervation in 45 patients with refractory hypertension. Patients had SBP of 160 mm Hg or higher despite using at least three antihypertensive medications and had an estimated glomerular filtration rate (eGFR) of 45 mL/min/1.73 m2 or higher.
Significant, sustained reductions
“Significant and sustained reductions in blood pressure were achieved with renal sympathetic denervation involving a brief, simple percutaneous procedure,” Dr. Krum said.
Patients experienced 21 and 10 mm Hg reductions in SBP and DBP, respectively, at three months; 24 and 11 mm Hg reductions at nine months; and 27 and 17 mm Hg reductions at 12 months (nine patients). The above results were reported on successively fewer patients for each follow-up period. In five untreated controls, BP at nine months rose by 26 and 17 mm Hg, respectively, Dr. Krum reported. The results were simultaneously reported in The Lancet (2009; published online ahead of print).
Effect on medication use
The treatment had little effect overall on the number of patients requiring medication, but Dr. Krum explained that investigators needed to determine the unique effect of the intervention, so, per protocol, they requested that background antihypertensive therapy be kept as stable as possible.
The mean duration of the actual ablation procedure was 38 minutes, and treatment was delivered without complications in 43 of 45 patients. The actual skin-to-skin time of the entire procedure was not reported. The investigators observed no major complications with respect to the renal artery or kidney and no long-term vascular complications. Some reinnervation may have occurred, he said, but if it has, it is probably “anatomical only” and has not affected BP-lowering efficacy at least out to 12 months.
Remarking on both approaches, panelist Marvin Konstam, MD, professor of medicine at Tufts University School of Medicine and director of the Cardiovascular Center at Tufts Medical Center in Boston, said he “applauded” both investigators for their innovative work, which has implications for some of the 65% of patients who are “not truly treated to goal” by current approaches.