The American College of Cardiology’s annual Scientific Sessions are regularly a source of controversy and competition, but medtech titan Medtronic’s (NYSE:MDT) highly anticipated renal denervation study results may have been the most confounding.
Seemingly conflicting reports from Medtronic’s SYMPLICITY HTN-3 clinical trial and SYMPLICITY registry alternately painted renal denervation as either an ineffective treatment or a valuable option for patients with drug-resistant hypertension.
In results from the HTN-3 trial renal denervation barely lowered blood pressure compared with a sham procedure, falling short of endpoints for efficacy. The therapy resulted in a 2.39 mm Hg greater reduction in blood pressure at 6 months than the sham arm, failing to achieve statistical significance. Ambulatory readings taken over a 24-hour period showed a 1.96 mm Hg difference compared with the sham control arm.
In registry outcomes, however, data from more than 750 patients showed an 11.9 mm Hg reduction in blood pressure at 6 months. Among patients with a baseline at or above 160 mm Hg, average reduction was 21.4 mm Hg Ambulatory readings, which included about 400 patients, showed a 7.9 mm Hg reduction in blood pressure.
Since there was no placebo control and no blinding, it’s difficult to compare to the registry outcomes with the clinical trial, which was the most rigorous study to date to examine renal denervation in treatment of drug-resistant hypertension.
Some, including registry results presenter Dr. Michael Bohm, argued that the studies are too different to be considered together. The data is complementary, but not parallel, Bohm told Medscape.
Some physicians have said it’s too early to make the call on renal denervation, but others have been less optimistic. One study insider said anonymously earlier this year that renal denervation is "highly unlikely" to make the grade for treating hypertension.
Others remain optimistic that renal denervation can play a role in patient treatment. Cardiologist Dr. Darrel Francis, who correctly predicted that the HTN-3 outcomes would fail to excite, has defended the technology as a good option for the right patients.
"Symplicity 3 teaches us that the history of denervation needs to be wiped, and started afresh, relying only on randomized blinded data. At least now the unknown unknowns are becoming known unknowns," Francis told MassDevice.com. "It is a huge relief that at last there is a trial reported that has the design features that have for the last 2 decades been known to be essential for trials of intervention for hypertension: randomization and blinding.
Competition in valves
Medtech’s giants highlighted the latest on their transcatheter valve implantation systems, with Medtronic, Edwards Lifesciences (NYSE:EW) and Boston Scientific (NYSE:BSX) both touting strong performance data on their valves.
Medtronic touted 1-year data on its newer Melody transcatheter pulmonary valve, saying the device performed well in patients at 1 year of follow-up. The technology has FDA Humanitarian Device Exemption and has been available since 2010. The study included patients with ages ranging from 5 to 45, with an average age of 20 years old, according to Reuters.*
Medtronic also made progress on its higher-profile CoreValve transcatheter aortic valve, saying that the company won approval to skip an FDA advisory panel hearing on treating high-risk patients.
Edwards made its own TAVI announcement, saying that its Sapien XT system bested CoreValve in a small head-to-head study. Sapien produced higher rates of overall "device success" in the 241-patient CHOICE study, Edwards said.
Not one to be left out, Boston Scientific provided a 3-month study update on its Lotus TAVI system, saying that the technology resulted in low rates of leakage. There were no reports of severe leakage at 90 days and 85.4% freedom from any kind of leakage, according to independent core lab assessments, Boston Scientific said.
Valve leakage is a major concern in TAVI devices, especially in the older generations of the technology. Leakage in the valve is an important indicator of mortality.
Updated April 3, 2014. This article mistakenly stated that the Melody valve won HDE in 2012; the exemption was granted in 2010.