At EuroPCR 2013, being held from 21st to 24th May, in Paris, France, preliminary results from the feasibility study of Medtronic's Symplicity Spyral multi-electrode, 6 Fr renal denervation catheter, showed safe, significant blood pressure reduction at one month in patients with treatment-resistant hypertension. Additionally, patients who had the renal denervation procedure with the catheter (n=29) had a mean procedure time of 21 minutes, a decrease of 33 minutes from the mean procedure time for the Symplicity Flex single-electrode catheter shown in the Symplicity HTN-2 trial. Nearly all of the patients in the one-month analysis had a radiofrequency (RF) treatment time of one minute per artery; two of the 29 patients received more than one treatment in a single artery.
The Symplicity Spyral catheter feasibility study is prospective, single-arm, non-randomised and will enrol 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 catheter. Its primary effectiveness endpoint is change in office blood pressure from baseline at six months.
At one month, patients in this study experienced an average blood pressure reduction of -16/-7 mm/Hg (p<0.001) from baseline. These results are consistent with the efficacy data seen in the Symplicity HTN-1 feasibility study for the Symplicity Flex single-electrode catheter, which showed an average blood pressure reduction of -19/-9 mm/Hg (p<0.01; n=143) after one month follow-up. Furthermore, average heart rate reduction for patients in the study was -4.3+/-11.0 beats per minute from baseline (p=0.047) to one month; pulse pressure also improved significantly following treatment with a reduction of -8.8+/14.9 mm/Hg (p<0.004).
Study investigators in this early experience with the Symplicity Spyral catheter reported no safety concerns. A total of 29 patients were treated with a 100 per cent 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 due to the application of RF energy to the vessel wall; no renal artery stenosis hypertensive crises or clinically meaningful changes in renal function were reported following the procedure.
The Symplicity Spyral catheter features four electrodes that deliver RF energy simultaneously and is designed to significantly reduce ablation time during renal denervation procedures. The new catheter is 6 Fr guide-compatible, highly conformable to artery shape and size encompassing vessel diameters of 3 to 8mm, and has a non-occlusive design. 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.
The catheter will be powered by an RF generator that will leverage the benefits of Medtronic's Symplicity treatment algorithm with its built-in safety features. The generator will include a touch-screen user interface that also will be compatible with the single-electrode Symplicity catheter. The Symplicity Flex single-electrode catheter is only available in the US and Japan for investigational use. The Symplicity Spyral renal denervation catheter is pending CE mark approval and not yet commercially available anywhere worldwide.