Feasibility Study of Medtronic's Symplicity Spyral Renal Denervation Catheter Presented at EuroPCR

May 21, 2013—Medtronic, Inc. (Minneapolis, MN) announced preliminary results from the feasibility study of its Symplicity Spyral multielectrode, 6-F renal denervation catheter. The data were presented during an oral session on May 23 at EuroPCR 2013 in Paris, France.

The Symplicity Spyral catheter feasibility study is a prospective, single-arm, nonrandomized investigation that will enroll approximately 50 patients at sites in Australia and New Zealand. The study's primary endpoint is acute procedure safety associated with the delivery and/or use of the Symplicity Spyral catheter. The primary effectiveness endpoint is change in office blood pressure from baseline at 6 months.

According to the company, the results showed safe, significant blood pressure reduction at 1 month in patients with treatment-resistant hypertension. Additionally, patients who had the renal denervation procedure with the Symplicity Spyral catheter (n = 29) had a mean procedure time of 21 minutes, a decrease of 33 minutes from the mean procedure time for the company's Symplicity Flex single-electrode catheter in the Symplicity HTN-2 clinical trial. Nearly all of the patients in the 1-month analysis had a radio frequency (RF) treatment time of 1 minute per artery; two of the 29 patients received more than one treatment in a single artery.

At 1 month, patients in this study experienced an average blood pressure reduction of -6/-7 mm Hg from baseline (P < .001). The company advised that these results are consistent with the efficacy data seen in the Symplicity HTN-1 feasibility trial for the Symplicity Flex single-electrode catheter, which showed an average blood pressure reduction of -19/-9 mm Hg in 143 patients after 1-month follow up (P < .01). Further, average heart rate reduction for patients in the study was -4.3 ± 11.0 beats per minute from baseline to 1 month (P = .047); pulse pressure also improved significantly after treatment, with a reduction of -8.8 ± 14.9 mm Hg (P < .004).

The study's principal investigator is Robert Whitbourn, MD, who is Director of the Cardiac Catheterization Labs and Coronary Intervention at St. Vincent's Hospital in Melbourne, Australia.

In Medtronic's press release, Dr. Whitbourn commented, “Early results of this trial are encouraging, as they indicate that the clinical outcomes of this multielectrode catheter are consistent with the well-established clinical data for the single-electrode Symplicity catheter. And, the possibility of reduced procedure times can have profound benefits for this patient population. The data from this early analysis are not entirely unexpected, given the single- and multielectrode catheters use a consistent helical ablation pattern and both leverage the Symplicity renal denervation treatment algorithms.”

In this early experience with the Symplicity Spyral catheter, the study investigators reported no safety concerns. A total of 29 patients were treated with a 100% acute success rate in accessing the vessels and delivering therapy. During the study, three procedural events were observed, with two pseudoaneurysms and one closure site complication, not related to RF energy delivery. There was one vessel irregularity on angiography caused by the application of radio frequency energy to the vessel wall. No renal artery stenosis hypertensive crises or clinically meaningful changes in renal function were reported after the procedure, stated Medtronic.

The Symplicity Spyral catheter features four electrodes that deliver RF energy simultaneously. It is designed to significantly reduce ablation time during renal denervation procedures. The catheter has a nonocclusive design, is compatible with a 6-F guide, and is highly conformable to artery shape and size, encompassing vessel diameters of 3¬–8 mm. This new design is intended to provide ease of deliverability and consistency of RF energy application while also enabling the treatment of a wide range of renal anatomies.

As noted in Medtronic's press release, the Symplicity Spyral catheter will be powered by a new RF generator that uses the company's Symplicity treatment algorithm and safety features. The new generator will include a new touchscreen user interface that will also be compatible with the single-electrode Symplicity catheter. The Symplicity Spyral renal denervation catheter is pending CE Mark approval and is not yet commercially available anywhere in the world.

The Symplicity Flex incorporates a single-electrode catheter, generator, and algorithms to deliver the renal denervation procedure. The Symplicity Flex's single-electrode catheter has been used in Europe and other international markets for more than 5 years as therapy for treatment-resistant hypertension. In the United States and Japan, the Symplicity Flex single-electrode catheter is available only for investigational use.