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Letter to FDA On Carotid Stenting

The following is President Richard Green's letter to the FDA requesting an opportunity to speak to FDA panel concerning the Cordis AngioGuard (TM) and Precise (TM) System as a representative of vascular surgeons.

April 8, 2004

Garetta Wood
Division of Cardiovascular Services
Food and Drug Administration

Dear Ms. Wood:
I am the current president of the Society for Vascular Surgery. I am also a practicing vascular surgeon and the Chairman of the Department of Surgery at Lenox Hill Hospital in New York City.  I am formally requesting an opportunity to speak to the FDA Panel considering approval of the Cordis AngioGuard TM and PreciseTM Stent System for carotid artery angioplasty and stenting.  I do so representing a group with a vast experience in the management of patients with cerebral vascular disease.

The Cordis Company and the principal investigators are to be congratulated for designing and conducting a randomized trial comparing carotid stenting with embolic protection to endarterectomy in a selected group of patients considered at high risk for endarterectomy.  They hypothesized an equivalency between stenting and endarterectomy in this defined subset of patients and their data appear to support their contention. While the definition of “high-risk” used in the SAPPHIRE Trial is not uniformly accepted by all vascular surgeons, we do agree that certain patients are likely to benefit from carotid angioplasty and stenting when performed at a level of expertise similar to that of the trialists. These patients include those with contralateral laryngeal nerve palsy, a history of radiation therapy to the neck, previous carotid endarterectomy with recurrent stenosis, and those with medical co-morbidities that might adversely affect the outcome in the opinion of the surgeons, interventionalists and anesthesiologists responsible for the patient. We believe however that this cohort and the patients in SAPPHIRE represent a small percentage of those in the general population currently undergoing carotid endarterectomy and that this study is not reflective of current national practice.

We cannot overstate how important we regard trials with expanded indications, powered sufficiently to allow the data to determine any subsequent expansion of the indications for usage. Pending the results of large-scale experience from a single-arm (registry) or dual-arm (randomized) trials with independently adjudicated one-year outcome data, there are little data to support the use of carotid stenting in lower risk patients.  We are concerned that because the differentiation between high and low risk is not always clear and the monitoring of usage nearly impossible that the procedure will be utilized in patient groups not adequately studied.  The adjudication of “high-risk” is best done by a collaborative decision making process including multiple physicians and a surgeon that performs carotid endarterectomy.

If approved, carotid stenting should be performed by those operators with expertise not just on the technical aspects of delivering a stent to a target, but in all the pre- and post-procedure components that carotid endarterectomy required. This means that a thorough knowledge of the natural history of carotid bifurcation disease, medical co-morbidities, possible neurological consequences of both stroke and reperfusion and the ability to provide post-procedural care are necessary in addition to the requisite technical skills. We are concerned that no one interested group of physicians has the expertise in all these areas.  Multi-specialty coordination and cooperation will be required to achieve the outstanding outcomes that we all desire.

Because carotid stenting is a new procedure to the majority of vascular surgeons, interventional cardiologists, and interventional radiologists, training and credentialing present unique challenges. Each of the vested specialties has a different skill set and knowledge base. Specifically, there are groups that have more expertise in the catheter aspects of carotid stenting, groups that have more expertise in the diagnostic components, namely cerebral angiography, and those with more expertise in the management of the patients. No one of these ingredients is more or less critical to a successful outcome. We are encouraged that many interested professional societies have worked collaboratively for the creation of new CPT and ICD-9 codes and to address the national non-coverage decision for carotid stenting over the past nine months. We are discouraged that similar collaboration has not occurred relative to training, competency and credentialing standards. The tendency of each group to emphasize its strengths and minimize its weaknesses relative to carotid stenting is self-serving and not in the best interests of patient care.  It is critical that each of the representative societies establish its own set of responsible guidelines for credentialing requirements with the understanding that final decisions will be made locally.

We believe that anyone who wishes to perform carotid artery stenting should possess at a minimum the skills associated with an advanced interventionalist, regardless of the target lesions treated. Certainly a familiarity of the anatomy and behavior of the cerebral vessels is essential but no less so than coronary, renal or lower extremity vascular anatomy. Many of the skills and tools required to perform renal or superficial femoral artery angioplasty and stenting are transferable to the extracranial circulation. Other variables being equal, practitioners experienced in coronary, renal, lower extremity, and subclavian interventions will require fewer procedures to become proficient in carotid stenting.  Those without such experience will require many more procedures.

Vascular surgical training requirements have not in the past included a minimum numbers of cases as a requisite for certification. Rather, a curriculum is approved, training programs are reviewed for compliance and individuals are certified and then qualified. We believe that case numbers are less relevant than demonstrated competence. We agree conceptually with the certification process developed by the CREST investigators whereby performance parameters are included in the determination of competence.

Lastly, I would like to comment on the proposition that an arbitrary minimum of diagnostic cerebral angiograms be the prerequisite credentialing requirement for carotid stenting.  The Panel should be aware that there remain relatively few indications for diagnostic angiograms performed as sole procedures. To create any threshold to training on this basis creates an unacceptable risk to the patients, as there is a definite incidence of stroke from the diagnostic procedure alone irrespective of an intervention. Further, such diagnostic procedures do not provide experience in the more complex techniques such as guide/sheath cannulation of the common carotid artery, use of embolic protection devices, and stent deployment.  We would hope that the neuro-interventionalists would agree to collaborate in the care of these patients rather than create artificial and potentially dangerous barriers.

In conclusion, the Society for Vascular Surgery is supportive of the efforts to bring this important technology forward. While we still believe that carotid endarterectomy is appropriate for the majority of patients with carotid artery stenoses and indications for intervention, we support the judicious use of carotid artery stenting in bona fide “high-risk” patients. We recognize the challenge of introducing this technology in the larger community and will continue to work with our medical colleagues and industry to achieve our goal of improved patient care.

Sincerely Yours,

Richard M. Green, M.D.
President, Society for Vascular Surgery

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