Standards of Practice for Carotid Angioplasty and Stenting
Standards of Practice for Carotid Angioplasty and Stenting
In order to facilitate comparison among series of patients treated with CAS, a common set of reporting data is suggested. We have outlined particular areas in greater detail below.
It is well-established that there are certain non-modifiable and modifiable risk factors for stroke. Demographic information regarding patient age, gender and race contains useful information about non-modifiable risk factors. Documentation of medical history to include hypertension, cigarette smoking, diabetes and dyslipidemia are also important in order to identify modifiable risk factors.
We recommend that data regarding demographic information include well-established non-modifiable and modifiable stroke risk factors.
Patients are considered to have symptomatic carotid stenosis based on the criteria from NASCET. Symptomatic patients must have had a hemispheric transient ischemic attack (TIA), with distinct focal neurological dysfunction or monocular blindness persisting <24 h or a non-disabling stroke with persistence of symptoms for >24 h within the previous 180 days.
We recommend that data regarding symptoms include cerebral or retinal TIAs or non-disabling stroke within the previous 180 days.
The original criteria for patients to be considered high risk for surgery were defined in the SAPPHIRE trial. These included clinically significant cardiac disease, severe pulmonary disease, age >80 years and certain anatomic factors. Criteria for high risk have been further defined by the AHA/ASA and include both medical and anatomic factors. Medical factors are class III/IV congestive heart failure (CHF), class III/IV angina, left main coronary artery disease (CAD), ≥2-vessel CAD, left ventricular ejection fraction (EF) ≤30%, recent MI, severe lung disease or severe renal disease.
We recommend that data regarding medical comorbidities include the presence of severe CHF, angina, CAD, low EF, recent MI and severe lung or renal disease.
As with medical factors that make patients high risk for surgery, anatomic factors were also defined by the SAPPHIRE trial. These were contralateral carotid occlusion, contralateral laryngeal nerve palsy, previous radical neck surgery or neck radiation and recurrent stenosis after prior CEA. The AHA/ASA has further defined these factors and the current anatomic factors are prior neck surgery (such as radical neck dissection), neck irradiation, post-endarterectomy restenosis, surgically inaccessible lesions, contralateral carotid occlusion, contralateral vocal cord palsy or the presence of a tracheostomy.
We recommend that data regarding these anatomic factors be reported.
Carotid stenosis is usually found either as the result of a screening test in an asymptomatic patient or as the result of a work-up for stroke or transient ischemic events. Doppler ultrasonography, CT angiography (CTA) and magnetic resonance angiography (MRA) are all capable of providing information on the degree of stenosis, but the gold standard test remains catheter angiography. The NASCET method for calculating the degree of stenosis measures the luminal diameter at the level of the stenotic lesion (R) compared with the diameter of the normal distal internal carotid artery beyond the carotid bulb (D) where the walls of the internal carotid artery first become parallel to each other.
Although degree of stenosis is the most studied independent risk factor, certain features of plaque morphology such as irregularity and ulceration have been identified in the ECST and NASCET trials as associated with an increased risk of ipsilateral stroke at all degrees of stenosis. However, catheter-based angiography may be limited in identifying ulcers. Non-invasive imaging techniques such as MRI may allow the pre-procedure identification of unstable plaque features like ulceration or disrupted fibrous plaque. We recommend reporting of plaque features such as irregularity and ulceration identified on angiography or non-invasive imaging.
We recommend that the degree of stenosis be calculated by the NASCET method applied to either non-invasive imaging (CTA, MRA), inferred from ultrasound data or applied to catheter angiography and be reported both pre- and post-treatment.
Embolic stroke is a clear concern when performing CAS. Distal protection devices were developed to minimize the chance of emboli reaching the cerebral circulation during CAS; however, there is no clear consensus regarding the use of these devices. In the SAPPHIRE trial, CAS was performed with the use of EPDs but, in the CREST trial, an EPD was used 'whenever feasible'. This acknowledges that the feasibility of EPD use, technical success, is variable depending upon patient anatomy and operator experience. Although the goal of limiting emboli is foremost, the use of an EPD increases the complexity of the procedure for several reasons including the operator learning curve, patient intolerance to flow arrest or reversal and device-induced vasospasm or difficult retrieval with distal filter systems. Proximal protection includes both circulatory control in the form of flow arrest or flow reversal paradigms and is an alternative to distal occlusion or filter protection in which the counterembolic condition is established prior to lesion crossing.
We recommend that data regarding the endovascular technique include whether or not an EPD was used and the type of system that was used.
The goal for CAS is reduction of ipsilateral stroke and/or death. To date, studies have used perioperative (within 30 days) events of minor stroke, major stroke, MI and death as outcomes. Long-term events (ie, ≥1-year risk) have included ipsilateral stroke, ipsilateral disabling stroke, any stroke and death. Long-term follow-up of patients in the CREST trial with Doppler ultrasound showed a 6% rate of restenosis or occlusion 2 years after CAS. Female sex, diabetes and dyslipidemia were independent predictors of restenosis. Monitoring for restenosis may allow intervention prior to a new stroke. Patients have typically been followed annually for at least 2–5 years.
We recommend that data regarding clinical follow-up include perioperative (within 30 days) assessment for stroke, MI or death. In addition, we recommend that patients be followed annually and data regarding restenosis, stroke and death be collected. We suggest a minimum of 2 years of clinical follow-up. Follow-up imaging with ultrasound is recommended, with consideration for alternative modalities if an abnormality is seen on ultrasound.
Reporting Standards
In order to facilitate comparison among series of patients treated with CAS, a common set of reporting data is suggested. We have outlined particular areas in greater detail below.
Demographics
It is well-established that there are certain non-modifiable and modifiable risk factors for stroke. Demographic information regarding patient age, gender and race contains useful information about non-modifiable risk factors. Documentation of medical history to include hypertension, cigarette smoking, diabetes and dyslipidemia are also important in order to identify modifiable risk factors.
We recommend that data regarding demographic information include well-established non-modifiable and modifiable stroke risk factors.
Symptoms
Patients are considered to have symptomatic carotid stenosis based on the criteria from NASCET. Symptomatic patients must have had a hemispheric transient ischemic attack (TIA), with distinct focal neurological dysfunction or monocular blindness persisting <24 h or a non-disabling stroke with persistence of symptoms for >24 h within the previous 180 days.
We recommend that data regarding symptoms include cerebral or retinal TIAs or non-disabling stroke within the previous 180 days.
Comorbidities
The original criteria for patients to be considered high risk for surgery were defined in the SAPPHIRE trial. These included clinically significant cardiac disease, severe pulmonary disease, age >80 years and certain anatomic factors. Criteria for high risk have been further defined by the AHA/ASA and include both medical and anatomic factors. Medical factors are class III/IV congestive heart failure (CHF), class III/IV angina, left main coronary artery disease (CAD), ≥2-vessel CAD, left ventricular ejection fraction (EF) ≤30%, recent MI, severe lung disease or severe renal disease.
We recommend that data regarding medical comorbidities include the presence of severe CHF, angina, CAD, low EF, recent MI and severe lung or renal disease.
Anatomic Factors
As with medical factors that make patients high risk for surgery, anatomic factors were also defined by the SAPPHIRE trial. These were contralateral carotid occlusion, contralateral laryngeal nerve palsy, previous radical neck surgery or neck radiation and recurrent stenosis after prior CEA. The AHA/ASA has further defined these factors and the current anatomic factors are prior neck surgery (such as radical neck dissection), neck irradiation, post-endarterectomy restenosis, surgically inaccessible lesions, contralateral carotid occlusion, contralateral vocal cord palsy or the presence of a tracheostomy.
We recommend that data regarding these anatomic factors be reported.
Degree of Stenosis
Carotid stenosis is usually found either as the result of a screening test in an asymptomatic patient or as the result of a work-up for stroke or transient ischemic events. Doppler ultrasonography, CT angiography (CTA) and magnetic resonance angiography (MRA) are all capable of providing information on the degree of stenosis, but the gold standard test remains catheter angiography. The NASCET method for calculating the degree of stenosis measures the luminal diameter at the level of the stenotic lesion (R) compared with the diameter of the normal distal internal carotid artery beyond the carotid bulb (D) where the walls of the internal carotid artery first become parallel to each other.
Although degree of stenosis is the most studied independent risk factor, certain features of plaque morphology such as irregularity and ulceration have been identified in the ECST and NASCET trials as associated with an increased risk of ipsilateral stroke at all degrees of stenosis. However, catheter-based angiography may be limited in identifying ulcers. Non-invasive imaging techniques such as MRI may allow the pre-procedure identification of unstable plaque features like ulceration or disrupted fibrous plaque. We recommend reporting of plaque features such as irregularity and ulceration identified on angiography or non-invasive imaging.
We recommend that the degree of stenosis be calculated by the NASCET method applied to either non-invasive imaging (CTA, MRA), inferred from ultrasound data or applied to catheter angiography and be reported both pre- and post-treatment.
Use of Embolic Protection Devices (EPDs)
Embolic stroke is a clear concern when performing CAS. Distal protection devices were developed to minimize the chance of emboli reaching the cerebral circulation during CAS; however, there is no clear consensus regarding the use of these devices. In the SAPPHIRE trial, CAS was performed with the use of EPDs but, in the CREST trial, an EPD was used 'whenever feasible'. This acknowledges that the feasibility of EPD use, technical success, is variable depending upon patient anatomy and operator experience. Although the goal of limiting emboli is foremost, the use of an EPD increases the complexity of the procedure for several reasons including the operator learning curve, patient intolerance to flow arrest or reversal and device-induced vasospasm or difficult retrieval with distal filter systems. Proximal protection includes both circulatory control in the form of flow arrest or flow reversal paradigms and is an alternative to distal occlusion or filter protection in which the counterembolic condition is established prior to lesion crossing.
We recommend that data regarding the endovascular technique include whether or not an EPD was used and the type of system that was used.
Clinical Follow-up
The goal for CAS is reduction of ipsilateral stroke and/or death. To date, studies have used perioperative (within 30 days) events of minor stroke, major stroke, MI and death as outcomes. Long-term events (ie, ≥1-year risk) have included ipsilateral stroke, ipsilateral disabling stroke, any stroke and death. Long-term follow-up of patients in the CREST trial with Doppler ultrasound showed a 6% rate of restenosis or occlusion 2 years after CAS. Female sex, diabetes and dyslipidemia were independent predictors of restenosis. Monitoring for restenosis may allow intervention prior to a new stroke. Patients have typically been followed annually for at least 2–5 years.
We recommend that data regarding clinical follow-up include perioperative (within 30 days) assessment for stroke, MI or death. In addition, we recommend that patients be followed annually and data regarding restenosis, stroke and death be collected. We suggest a minimum of 2 years of clinical follow-up. Follow-up imaging with ultrasound is recommended, with consideration for alternative modalities if an abnormality is seen on ultrasound.