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Renal nerve stimulation shows promise for identifying appropriate patients for renal denervation
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A first-in-man study shows that renal nerve stimulation appears to be safe and effective along the renal artery and yields large variation in temporary changes in BP per patient and per anatomic location.
The change in systolic BP to electrical stimulation has the potential to be a diagnostic tool for identifying an appropriate patient population for renal sympathetic denervation, and the responsiveness at different locations could serve as treatment targets along the renal artery that could boost the treatment’s success, the researchers wrote.
The prospective, multicenter, open-label, single-arm feasibility study was conducted at three sites in Europe. Diagnostic mapping of the nerves using electric renal nerve stimulation was performed using the ConfidenHT system (Pythagoras Medical).
For the procedure, patients were preloaded with aspirin 300 mg and advised to continue treatment for at least 1 month. Heparin was then administered before the procedure to achieve an activated clotting time greater than 250 seconds. After administration of local or general anesthesia, femoral access was achieved and an 8F sheath was used, and the Symplicity Spyral electrode catheter (Medtronic) or EnligHTN ablation catheter (St. Jude Medical) was used.
Clinical follow-up occurred at 30 days and 3 months after the procedure. The primary endpoint was change in systolic BP from before the procedure to follow-up.
Among the 20 patients (mean age, 60 years; nine men; mean office BP, 156/89 mm Hg) included in the study, there were no periprocedural events, nor were there any serious adverse events reported at 30-day follow-up. One patient experienced a device-related event — myalgia in the back — and three patients experienced procedure-related events. However, all events were resolved at 3 months. There were also no changes in renal function between baseline and both follow-up time points.
Of the 194 stimulations performed, 119 were performed using 2 mA amplitude, 61 were performed using the 4 mA amplitude and 14 were performed using different amplitudes ranging from 2 mA to 10 mA. The researchers performed an average of 9.7 stimulations per patient.
There was variation in response to the electrical stimulation among different anatomic locations in the arteries and among different patients, according to the data. Overall, the average change in systolic BP was 9 mm Hg and varied from 4 mm Hg to 21 mm Hg. Additionally, the average change in mean arterial pressure was 6 mm Hg and varied from 3 mm Hg to 14 mm Hg.
Among the 119 stimulations performed with 2 mA amplitude, the maximum change in systolic BP was 8.3 mm Hg (P < .001), whereas the maximum change in systolic BP was 10.1 mm Hg among the 61 stimulations performed with 4 mA amplitude (P < .001).
There was no significant difference in systolic BP response between the proximal, mid, distal and branch locations with 2 mA amplitude; however, with 4 mA amplitude, stimulation resulted in greater changes in systolic BP response at ostial vs. non-ostial locations (23 mm Hg vs. 9 mm Hg; P = .003).
Results showed no difference in response to stimulation among patients who did compared with those who did not undergo subsequent renal sympathetic denervation.
The researchers also found no differences with stimulation performed at 2 mA or 4 mA in patients who were using vs. not using beta-blockers.
Although promising, the benefits of renal nerve stimulation must be confirmed in larger studies, the researchers wrote. – by Melissa Foster
Disclosures: This study was sponsored by Pythagoras Medical. Tsioufis reports receiving grants or honoraria from AstraZeneca, Bayer, Boehringer Ingelheim, Chiesi, ELPEN, Medtronic, Novartis, Pfizer, Pharmanel, Pythagoras, Recordati, Sanofi, Servier, St. Jude Medical, Vianex and WinMedica. Please see the study for all other authors’ relevant financial disclosures.
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