SCAI Drafts Guidance on Renal Denervation for Hypertension
Anticipating US Food and Drug Administration (FDA) approval of at least one investigational device for renal denervation (RDN) as a treatment for hypertension (HTN) refractory to medical therapies, the Society for Cardiovascular Angiography and Interventions (SCAI) is asking its members and the public to provide input on a draft position statement to guide use of the procedure.
Released this week just before SCAI’s annual meeting, the draft addresses appropriate patient selection, best practices for procedural techniques, measures for operator competence, recommendations for operator and staff training, and guidance for hospitals and centers that want to adopt RDN. SCAI is requesting feedback by June 14.
“With the anticipated FDA approval of renal denervation, there will be a need for SCAI to formulate an official position around clinical competence and training standards, best practices, and institutional and operator requirements for RDN,” Herbert D. Aronow, MD, MPH, chair of the statement writing committee, told theheart.org | Medscape Cardiology.
RDN is an endoscopic procedure that disrupts the sympathetic nerves near the renal arteries. A number of studies, including sham-controlled, randomized trials, have shown that RDN can achieve short-term reductions in blood pressure for patients for whom HTN medications don’t work. Two devices are awaiting FDA premarket approval: the Paradise uRDN system, by ReCor Medical; and the Symplicity Spyral device, by Medtronic.
However, the trajectory of RDN has been uneven, said Aronow, president of the Society for Vascular Medicine and medical director for heart and vascular services and Benson Ford Chair in Cardiology at Henry Ford Health in Detroit.
“Despite supportive early animal and human data, the first sham-controlled randomized trial of RDN was negative on its primary endpoint,” he said. “Modifications to patient inclusion/exclusion criteria, refinements in denervation technology and protocols, and selection of more appropriate study endpoints resulted in a series of positive randomized, sham-controlled trials. These second-generation trials found that RDN, when compared with sham therapy, substantially reduced ambulatory and office blood pressures.”
The draft is available for review at the SCAI website. Comments may be submitted via a link to a questionnaire.
“Through the open comment process, we are hoping to gain broad perspective from stakeholders, including clinicians, hospitals, payers, professional societies, industry and patients,” Aronow said. “By incorporating this feedback, we hope to enhance the quality of the document before we submit it for publication.”
The bulk of the SCAI draft position statement is devoted to patient selection and procedural and technical considerations. “We believe it will serve as a roadmap for the successful launch of RDN programs around the United States,” Aronow said.
Patient Selection Considerations
The draft statement notes that RDN for all patients with uncontrolled HTN “would not currently be practical.” The average age of patients for whom RDN showed effectiveness in the cited clinical trials was less than 60 years. The effectiveness of RDN for patients in whom arterial stiffness is a primary driver of HTN “is less certain,” the statement noted.
Patients who may benefit most from RDN are those with limited medical treatment options. Initially, RDN was tried on patients who had continued to experience resistant HTN despite taking three or more medications, including a diuretic, the statement noted. But even nonadherent patients may derive some potential benefit from RDN.
The statement also added that RDN isn’t a panacea; about one third of trial patients didn’t respond to the procedure. The most reliable predictor of response may be higher levels of baseline systolic blood pressure, otherwise known as Wilder’s principle. The statement listed other potential markers of success, including higher nocturnal blood pressure and wider swings in nocturnal blood pressure.
Procedural and Technical Considerations
The statement also provided direction on a protocol for RDN procedures. The preprocedure evaluation should include noninvasive imaging to rule out disqualifying secondary causes of HTN, such as renal artery stenosis or fibromuscular dysplasia.
Patient characteristics should drive the selection of imaging modality, and availability as well as local expertise should be taken into account. The statement gave CT angiography or magnetic resonance (MR) angiography the edge over duplex ultrasound.
The statement also noted a number of anatomic considerations, citing preclinical analyses that “consistently reinforce” circumferential, perivascular RDN to ablate the renal nerves. In planning the procedure, consideration should be given to accessory renal arteries.
Additionally, operators should have training in obtaining access, and they should be familiar with different catheters and console devices as well as troubleshooting.
Training, Competency, and Institutional Requirements
Interventional cardiologists who want to perform RDN should demonstrate proficiency in a number of specific skill sets germane to the procedure, from arterial vascular access and hemostasis to recognizing and treating potential renovascular complications.
For institutions that want to offer RDN, the statement offered a number of requirements. One is to designate a primary physician stakeholder who’s well versed in HTN management to oversee the long-term management of RDN patients.
The institution must have a dedicated HTN program and a multidisciplinary team to manage treated patients. Requirements for RDN referral centers range from operators experienced with FDA-approved RDN devices to an infrastructure that includes CT or MR angiography to identify appropriate candidates.
“Renal denervation has been a long time coming, and it’s a great example of how academicians, clinicians and industry leaders can partner to move the cardiovascular field forward, addressing a major public health issue for which alternative solutions are greatly needed,” Aronow said.
Aronow has served as an unpaid council member for Medtronic and as a paid moderator for ReCor.
Richard Mark Kirkner is a medical journalist based in the Philadelphia area.
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