4 Efficacy

4 Efficacy

This section describes efficacy outcomes from the published literature that the committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.

4.1 In a comparative study of 64 patients treated by transcervical carotid artery stenting with flow reversal (n=31) or transfemoral carotid artery stenting with distal filter protection (n=33), there were no reports of stroke after stenting in either group. In a comparative study of 55 patients treated by transcervical carotid artery stenting with flow reversal or transfemoral carotid artery stenting with distal filter protection, 6% (2/31) of patients had a transient ischaemic attack (TIA) and none had a stroke in the transcervical carotid artery stenting group. In the transfemoral carotid artery stenting group, 4% (1/24) of patients had a TIA and 4% (1/24) had a stroke (timing not reported). In a prospective case series of 212 patients treated by transcervical carotid artery stenting with flow reversal, stroke occurred in 2% (4/212) of patients within 30 days of the procedure; there was 1 TIA and 3 major strokes.

4.2 In the comparative study of 64 patients treated by transcervical carotid artery stenting or transfemoral carotid artery stenting, there were no significant changes in the Rankin stroke scale after the procedure in either group.

4.3 In the same study of 64 patients, asymptomatic new ischaemic cerebral lesions were diagnosed on diffusion-weighted MRI in 13% (4/31) of patients in the transcervical group compared against 33% (11/33) in the transfemoral group (p=0.03). In a case series of 48 patients treated by transcervical carotid artery stenting with flow reversal, there were 16 new ischaemic lesions (diagnosed on diffusion-weighted MRI 3 days after the procedure) in 14% (6/43) of patients (mean of 2.7 lesions per patient, range 2–4). All lesions were ipsilateral to the operated carotid artery. In 4 out of 6 patients, the new lesions remained asymptomatic.

4.4 In a case series of 97 patients treated by transcervical carotid artery stenting with flow reversal, 3% (3/103) of procedures were converted to endarterectomy. The reasons for the conversions were common carotid dissection with the entry sheath, inability to cross the lesion in the internal carotid artery with the guide wire and severe agitation in 1 patient who needed conversion to general anaesthesia. In the patient with severe agitation the surgeon chose to proceed with an endarterectomy rather than stenting.

4.5 In a comparative study of 81 patients treated by transcervical carotid artery stenting with flow reversal (n=36) or carotid endarterectomy (n=45), there were high-intensity transient signals detected by transcranial Doppler sonography during the procedure in 3% (1/36) of patients treated by transcervical carotid artery stenting (not reported for the carotid endarterectomy group). In a prospective case series of 62 patients treated by transcervical carotid artery stenting with flow reversal, there were perioperative high-intensity transient signals reported in 6% (2/62) of patients.

4.6 In the comparative study of 81 patients treated by transcervical carotid artery stenting or carotid endarterectomy, there was an increase in mean cerebral artery flow velocity (measured by transcranial Doppler) after completion of the procedure in 100% (36/36) of patients treated by transcervical carotid artery stenting. In the prospective case series of 62 patients treated by transcervical carotid artery stenting with flow reversal, there was a significant improvement in the middle cerebral artery mean flow velocity and pulsatility index on completion of the procedure.

4.7 The specialist advisers listed the following key efficacy outcomes: reduced incidence of clinical neuro-embolic events and a decreased rate of new ischaemic lesions on brain MRI post-procedure (a surrogate marker).

  • National Institute for Health and Care Excellence (NICE)