VIVA 2011: PROOF Feasibility Study of a Novel Transcervical Neuroprotection System in Carotid Revascularization

October 19, 2011—First-in-man results from the PROOF study of a novel transcervical neuroprotection device for use during hybrid carotid artery stenting were presented by Sumaira Macdonald, MD, PhD, at the VIVA 2011: Vascular Interventional Advances meeting in Las Vegas, Nevada.

The PROOF study is a single-arm feasibility study using the MICHI (Minimally Invasive Cervical Hybrid Intervention) neuroprotection system (NPS) (Silk Road Medical, Inc. Sunnyvale, CA) in patients who are candidates for carotid artery revascularization. The MICHI NPS enables transcervical access via a mini-cut at the common carotid artery just above the clavicle and carotid stenting under neuroprotective flow reversal in a procedure known as flow-altered short transcervical carotid artery stenting (FAST-CAS).

The primary endpoints of PROOF are major stroke, myocardial infarction, or death from the index procedure through 30 days. In a subgroup, procedural microembolization was studied by performing diffusion-weighted magnetic resonance imaging (DW-MRI) examinations pre- and postprocedure.

According to Dr. Macdonald, 65 patients were treated with FAST-CAS using the MICHI NPS between March 2009 and September 2011 at two centers in Düsseldorf, Germany. No primary endpoint events were reported. One minor contralateral stroke was reported at 30 days in a patient who was free of lesions on pre- and postprocedural DW-MRI scans. This minor stroke was adjudicated to be unrelated to the procedure or the device. In the DW-MRI subgroup (n = 48), eight patients (16.7%) showed evidence of new ischemic brain lesions, none of which had any clinical sequelae. All scans were submitted to a core laboratory in the United States and were evaluated in a blinded fashion by two independent neuroradiologists. In comparison with other carotid stenting strategies, this is the lowest DW-MRI new white lesion rate ever reported and is comparable with the carotid endarterectomy (CEA) limb of the ICSS (International Carotid Stenting Study) DW-MRI substudy, stated Dr. Macdonald.

The PROOF investigators concluded that this first-in-man experience showed that FAST-CAS performed with the MICHI NPS is a safe and feasible method for carotid artery revascularization. The low rate of myocardial infarction and cranial nerve injury is commensurate with transfemoral CAS and shows improvement over CEA, the low rate of stroke/death and new DW-MRI lesions is commensurate with CEA and shows improvement over transfemoral CAS, and the DW-MRI findings suggest that transcervical access and controlled blood flow reversal provide cerebral embolic protection similar to that seen with CEA.

Dr. Macdonald noted that ongoing studies include LOTUS, which will comprise the majority of a recently symptomatic population undergoing carotid stenting in Newcastle upon Tyne, United Kingdom, as well as the ROADSTER United States pivotal trial under the direction of Co-Principal Investigators Richard Cambria, MD, and Christopher Kwolek, MD.