Follow-Ups to 18 Months, and Beyond
The most thorough assessment so far of RD as an antihypertensive treatment came in the Symplicity HTN-2 trial, a multicenter, multinational trial that randomized 106 patients with drug-resistant hypertension. In the 6-month results from the study, the primary end point showed that among 49 patients who underwent RD, office blood pressure fell by an average of 32/12 mm Hg, compared with virtually no change among 51 controls (Lancet 2010;376:1903-9).
During the August meeting, researchers from the study reported follow-up data, which included 18-month results from 43 patients in the original intervention arm of the study and from an additional 31 patients originally randomized to the control arm but who crossed over to RD treatment after the first 6 months.
The 18-month results showed stability of the initial blood pressure reduction in both subgroups of patients, with average reductions in office blood pressure remaining at 32/12 mm Hg compared with baseline in the 43 patients from the original intervention arm, and an average 28/11 mm Hg cut in office pressure in the 31 crossover patients, compared with their baseline levels, said Dr. Murray D. Esler, professor of medicine at Monash University in Melbourne, and lead investigator for the study. Patients in the initially treated arm also had an average 7 beats/min reduction in heart rate, compared with baseline that was statistically significant.
"In our experience at Saarland University Hospital with more than 400 patients, they all achieved a blood pressure response" following renal denervation. --Dr. Michael Böhm.
For safety, the 18 month results showed "no signal that renal function was harmed," he said. One patient had a renal-artery dissection early in the study, caused by the stiff catheter tip used at the study’s start but since replaced with a more flexible tip, Dr. Esler said. Other safety events during follow-up included one episode of hypotension that required hospitalization, one "mild" incidence of "transient" acute renal failure, and two deaths unrelated to RD.
Dr. Esler and his collaborators also cited the 36-month follow-up results on 24 patients from the initial, uncontrolled study of RD using the Symplicity catheter, the Symplicity HTN1 study (Lancet 2009;373:1275-81). These patients continue to show a durable blood pressure response and no signs of adverse effects, renal or otherwise, in this small number of patients followed for a prolonged period, said Dr. Böhm, director of internal medicine at Saarland University Hospital. (The 3-year follow-up of these 24 patients was first reported last March at the annual scientific session of the American College of Cardiology.) A very encouraging finding was that among the small number of patients followed this long, the percentage of patients with clinically important blood pressure drops continued to accumulate, so that at 36 months 99% of treated patients responded, Dr. Böhm said.