Quality Improvement Guidelines for the Performance of Cervical Carotid Angioplasty and Stent Placement

PREAMBLE

THE joint Standards of Practice Committee of the American Society of Interventional and Therapeutic Neuroradiology (ASITN), American Society of Neuroradiology (ASNR), and the Society of Interventional Radiology (SIR) is comprised of experts in a broad spectrum of interventional practice from both the private and academic sectors of medicine. Individual members of the Standards of Practice Committee dedicate the vast majority of professional time to diagnostic and interventional practice and the joint committee includes representatives from radiology, neurosurgery, interventional radiology and interventional neuroradiology, a diverse constituency expert on the subject matter under consideration.

Technical documents specifying the exact consensus and literature review methodologies as well as the institutional affiliations and professional credentials of the authors of this document are available on request from SIR, 10201 Lee Highway, Suite 500, Fairfax, VA 22030.

METHODOLOGY

ASITN, ASNR, and SIR Standards of Practice documents are produced using the following process. Standards documents of relevance and timeliness are conceptualized by the Standards of Practice Committee members. A recognized expert is identified to serve as the principal author for the standard. Additional authors may be assigned depending on the magnitude of the project.

An in-depth literature search is performed with electronic medical literature data bases. Then a critical review and selection of peer-reviewed articles are performed based on study methodology, results, and conclusions. Data compiled from selected articles meeting evidence thresholds are used to develop content and to set standards.

When the evidence of literature is weak, conflicting, or contradictory, consensus for the parameter is reached by a minimum of 12 Standards of Practice Committee members with a Modified Delphi Consensus Method (1,2). For purposes of these documents, consensus is defined as 80% Delphi participant agreement on a value or parameter.

The draft document is critically reviewed by the Standards of Practice Committee members, either by telephone conference calling or face-to-face meeting. The finalized draft from the Committee is sent to the ASITN, ASNR, and SIR membership for further input/criticism during a 30-day comment period. These comments are discussed by the Standards of Practice Committee, and appropriate revisions made to create the finished standards document. Before its publication, the document was endorsed by the ASITN Executive Committee, ASNR Executive Committee, and the SIR Executive Council.

I. INTRODUCTION

This Quality Improvement Guideline for the Performance of Cervical Carotid Angioplasty and Stent Placement was developed by a writing group consisting of members from interventional neuroradiology, neurosurgery, neuroradiology, and interventional radiology. A thorough review of the literature was performed. Thresholds for quality assurance were difficult to set due to the relative paucity of data and lack of uniform reporting of clinical outcomes and complications. The ASITN, the ASNR, and the SIR recognize that brachiocephalic revascularization is undergoing rapid change in technology even as it is being increasingly adopted in clinical practice for the treatment of cerebrovascular pathologies (3). There is a critical need to encourage the development of procedures that may improve outcomes for patients with brachiocephalic and intracranial atherosclerotic stenoses. Furthermore, due to the implications concerning stroke prevention, the ASITN, ASNR, and SIR wish to encourage the careful and scientific study of the safety and efficacy of brachiocephalic revascularization as well as appropriate utilization of these techniques (3).

The published standard of practice for cervicocerebral angiography describes the minimum acceptable requirements for performance of the much less difficult and lower risk procedure of diagnostic cervicocerebral angiography (4); it is the purpose of this standard to describe the minimum prerequisite for the performance of the far more difficult and higher risk procedure of carotid artery angioplasty and stent placement (CAS). Far more experience and training and fewer complications during diagnostic cerebral angiography are expected of those who perform neurovascular interventions, similar to what is expected of those who perform coronary interventions. At a minimum, performance of CAS requires extensive prior experience and demonstrated competence with diagnostic cervicocerebral angiography, as well as experience with angioplasty and stent placement. Such requirements for additional training and experience in performing CAS have been recognized by the Accreditation Council for Graduate Medical Education (ACGME) as part of the specialty training requirements for endovascular surgical neuroradiology (5).

Stroke is the third leading cause of death in the United States, and ischemic stroke accounts for more than 80% of the morbidity and mortality associated with stroke. Many ischemic strokes are related to large- and medium-vessel atherosclerotic disease within the cerebrovascular circulation. Therefore, procedures such as angioplasty and/or stent placement to reverse critical cerebrovascular stenoses may have great importance. CAS is being performed with rapidly increasing frequency in the United States. We anticipate that more data regarding outcomes and complications will be collected and published in the near future (the National Institutes of Health–supported Carotid Revascularization: Endarterectomy vs. Stent Trial [CREST] as well as other controlled series have begun) (6). Therefore, we recommend that this standard be reviewed and, if necessary, revised within the next 24 months to remain applicable to contemporary medicine concerning this rapidly progressing technique.

CAS is an innovative procedure. Until the true risks and appropriate indications for this procedure are clearly known, the ASITN, ASNR, and SIR recommend that for patients who have average surgical risk, such as those who would have qualified for enrollment in the North American Symptomatic Carotid Endarterectomy Trial (NASCET) and the Asymptomatic Carotid Atherosclerosis Study (ACAS), CAS should only be performed as part of a randomized clinical trial or an institutional review board–approved investigational program. The inclusion and exclusion criteria for the NASCET and ACAS studies are summarized in Table 1. At this time, CAS has shown promise for the treatment of patients known to be at high risk of carotid endarterectomy (Yadav J, presented at the American Heart Association Scientific Sessions, Chicago, November 2002) (5). CAS should only be performed on appropriate patients by an individual or team with training and expertise in cerebrovascular angiography, pathophysiology, hemodynamics, and neurovascular interventions and/or carotid angioplasty/stent placement (7). This recommendation is further extended to encourage multidisciplinary input and concurring opinion in clinical decision making.

II. OVERVIEW

III. INDICATIONS AND CONTRAINDICATIONS

Definitions: Severe stenosis is 70% or greater diameter stenosis by NASCET measurement criteria. Preocclusive stenosis is 90% or greater diameter stenosis by NASCET criteria or NASCET definition of “near occlusion” (9).

• A. Acceptable Indications for CAS

     

  1.    Symptomatic, severe stenosis that is surgically difficult to access (eg, high bifurcation requiring mandibular dislocation) (103)

  2.    Symptomatic, severe stenosis in a patient with significant medical disease that would make the patient high risk for surgery (20–36,104–109, Table 2).

  3.    Symptomatic severe stenosis and one of the following conditions:

           

     •       a. Significant tandem lesion that may require endovascular therapy

     •       b. Radiation-induced stenosis (110,111)

     •       c. Restenosis after CEA (112,113)

     •       d. Refusal to undergo CEA after proper informed consent

     •       e. Stenosis secondary to arterial dissection

     •       f. Stenosis secondary to fibromuscular dysplasia

     •       g. Stenosis secondary to Takayasu arteritis (1,114)

  4.    Severe stenosis associated with contralateral carotid artery occlusion requiring treatment before undergoing cardiac surgery

  5.    Severe underlying carotid artery stenosis revealed after recanalization of carotid occlusion after thrombolysis for acute stroke (presumed to be the etiology of the treated occlusion) or to enable thrombolysis for acute stroke

  6.    Pseudoaneurysm (115)

  7.    Asymptomatic preocclusive lesion in a patient otherwise meeting criteria 1–3

• B. Relative Contraindications

     

  1.    Asymptomatic stenosis of any degree, except in particular circumstances, as described above (A4, A6, A7)

  2.    Symptomatic stenosis associated with an intracranial vascular malformation

  3.    Symptomatic stenosis in a patient with a subacute cerebral infarction

  4.    Symptomatic stenosis in a patient with a significant contraindication to angiography

• C. Absolute Contraindications

     

  1.    Carotid stenosis with angiographically visible intraluminal thrombus

  2.    A stenosis that cannot be safely reached or crossed by an endovascular approach

IV. QUALIFICATIONS AND RESPONSIBILITIES OF PERSONNEL

A. Rationale for Cervicocerebral Angiographic Skill

Official standards of training have existed for over a quarter century, are the hallmark of medical licensure, board examinations and residency programs, and are recognized as vital by the ACGME, the Federation of State Medical Boards of the United States, Inc., the American Board of Medical Specialties (ABMS), and the National Board of Medical Examiners® (NBME®) (116–118). Standards of training and for performance of medical and surgical procedures are necessary requirements for the practice of medicine. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) is working with two other accrediting organizations, the National Committee for Quality Assurance and URAC (formerly known as the Utilization Review Accreditation Commission), on coordinating and aligning patient safety standards. Medical societies and accreditation committees routinely formulate minimum standards for the protection and safety of patients, including those for board accreditation, residency training and the practice of medicine. Examples of such standards are those written by the American College of Cardiology (ACC) for the performance of coronary intervention (which require 300 coronary angiograms prior to coronary intervention) (119–121) as well as training and performance standards specifically for peripheral vascular intervention (122,123). Standards of performance and training specifically for peripheral vascular intervention have also been written by the AHA (124), the Society of Cardiac Angiography and Intervention (125), the Society of Interventional Radiology (126, 127) and the Society for Vascular Surgery (128). All training and performance standards above require substantial diagnostic angiographic experience prior to interventional practice in all vascular beds, typically 100 angiograms (119–128). Training standards specifically for neurovascular intervention, including carotid artery stenting, were written by a multispecialty group and unanimously endorsed by each executive committee of the American Society of Neuroradiology, the American Society of Interventional and Therapeutic Neuroradiology, the American Association of Neurological Surgeons, the Congress of Neurological Surgeons (CNS) and the AANS/CNS Section on Cerebrovascular Surgery (5). These neurointerventional training standards require 100 cerebral angiograms as a pre-requisite for entry into the ACGME-approved residency/fellowship in Endovascular Surgical Neuroradiology.

The American College of Radiology’s Standard of Practice for Cervicocerebral Angiography was formulated by a consensus panel of ACR, ASITN, ASNR, and SIR members (4). Cervicocerebral angiography has a proven set of indications, contraindications, risks, and benefits due to the fact that cervicocerebral catheterization is technically challenging and the organ supplied is uniquely vulnerable. The proper and safe performance of a cerebral angiogram is fundamental to the performance of cervical CAS, just as diagnostic coronary angiography skills have been recogized by the ACC as a pre-requisite for coronary vascular intervention (119–121).

Stroke is the most feared of all medical conditions and procedural complications. For this reason, any procedure that has “stroke” as a routine potential risk should be performed only by medical professionals with appropriate training and experience. The rate of stroke as a complication of diagnostic cerebral angiography in patients with asymptomatic carotid stenosis was approximately 1.2% in ACAS; this may be greater than the actual risk of stroke caused by the stenosis itself for many patients with asymptomatic stenosis (8,49). Importantly, it has been demonstrated that the amount of cervicocerebral angiographic exerience is inversely related to procedural complication rates, which translate into temporary and permanent strokes (129–133). Indeed, the argument has been raised by both vascular surgeons and neurologists that cervicocerebral angiography, even performed by neurovascular specialists, may be too dangerous to be performed for the indication of asymptomatic carotid artery stenosis (134,135). Operator risk factors for stroke/transient ischemic attack (TIA) complications from cerebral angiography are well known and include increased procedure and fluoroscopy time, increased number of catheters used, and performance of arch aortography (130,131,136). Many of the above-mentioned factors, including procedural time and multiple catheter use, are not independent and are typically related to inexperience and lack of specific training. In several studies, neurological complications (stroke and TIA) occurred more frequently when angiography was performed by a trainee or fellow rather than by an experienced neuroradiologist (130–132,134). A recent report has demonstrated that the rate of stroke during cerebral angiography when performed by an appropriately trained and experienced specialist is very low (137). However, a separate published report confirms that physicians without formal training in catheter angiography did indeed experience a learning curve associated with an unacceptable complication rate that decreased with angiographic experience (130). A significant learning curve has also been demonstrated for the carotid stent procedure itself as well as the use of cerebral embolic protection devices, thus necessitating appropriate training and experience in both components of the procedure: cervicocerebral angiography as well as the carotid stent procedure (78,86,99–102).

B. Physician Qualifications For Carotid Angioplasty And Stent Placement

1. The surgical team must possess particular fundamental knowledge and skills for the appropriate application and safe performance of CAS; these include

      

   •    a. A thorough knowledge of cerebrovascular anatomy, hemodynamics, physiology, and pathophysiology

   •    b. Sufficient knowledge of the clinical and imaging evaluation of patients with cerebrovascular disorders to determine those patients for whom CAS is indicated; this includes thorough knowledge of the clinical manifestations and the natural history of cerebrovascular ischemic disease

   •    c. Appreciation of the benefits and risks of CAS and the alternatives to the procedure, such as CEA and/or current medical therapy

   •    d. Familiarity with pharmaceutical agents potentially useful during endovascular procedures

   •    e. The ability, skills, and knowledge to evaluate the patient’s clinical status and to identify those patients who may be at increased risk, who may require additional pre- or postprocedure care, or who have relative contraindications to the procedure; in particular, the physicians must be capable of performing a clinical neurologic examination and understanding any relevant findings before, during, and after the procedure

   •    f. The capability to recognize procedure, neurologic, and angiographic complications related to the CAS procedure; recognition of angiographic complications necessitates a thorough knowledge of cerebrovascular anatomy and hemodynamics

   •    g. The capability to provide appropriate endovascular management of vascular complications related to the performance of CAS, including appropriate treatment of embolic complications

   •    h. The capability to provide the initial clinical management of complications of CAS; basic life support and treatment of cardiac arrhythmias must be immediately available; in addition, the trained personnel, equipment, and pharmacotherapeutics required to identify and to manage heart block, cardiac arrhythmias, and major blood pressure fluctuations must also be immediately available

   •    i. Adequate training in radiation physics and safety; the physician team must be familiar with the principles of radiation biology, the hazards of radiation exposure to both patients and medical personnel, and radiation monitoring requirements; such training and knowledge are important to maximize both patient and physician safety

2. The requirements for meeting the qualifications listed in (IV.B.1) may be met by obtaining the following training and experience. This training may be obtained through the appropriate ACGME-approved residency or fellowship (5,138) or through postgraduate experience that should include a, b, and c below. The postgraduate experiential training must be under the supervision of a qualified physician, defined as a physician who has already met the qualifications of section IV with acceptable indications and outcomes.

      

   •    a. Performance (under the supervision of a qualified physician and with at least 50% performed as the primary operator) of at least 200 diagnostic cervicocerebral angiograms with documented acceptable indications and outcomes for physicians with no prior catheter experience (4,139), or at least 100 diagnostic cervicocerebral angiograms with documented acceptable indications and outcomes for physicians with experience sufficient to meet the AHA requirements for peripheral vascular interventions (124).

   •    b. Arterial stent experience as either:

           

     1.       25 non–carotid stent complete procedures, plus attendance at and completion of a “hands-on” course in performance of CAS, plus performance and completion of at least four successful and uncomplicated CAS procedures as principal operator under the supervision of an on-site qualified physician; this must be a comprehensive course in which the attendees earn at least 16 hours of AMA category I continuing medical education credit

                 OR

     2.       Ten consecutive CAS procedures as principal operator under the supervision of an on-site qualified physician on patients treated for appropriate indications documented by a log of cases performed and with acceptable success and complication rates according to the thresholds contained in this guideline and the ACR guideline for cervicocerebral angiography (4,78,86)

   •    c. Substantiation in writing by the director of the department, the chief of the medical staff, or the chair of the credentials committee of the institution in which the training procedures were performed and the institution in which privileges will be granted that the surgical team is familiar with all of the following:

           

     1.       Indications and contraindications for CAS

     2.       Preprocedural assessment and intraprocedural physiologic, cerebrovascular, and neurologic monitoring of the patient

     3.       Appropriate use and operation of fluoroscopic and radiographic equipment and digital subtraction angiography systems

     4.       Principles of radiation protection, hazards of radiation exposure to the patient and to the radiologic personnel, and radiation monitoring requirements

     5.       Anatomy, physiology, and pathophysiology of the cerebrovascular system

     6.       Pharmacology of contrast agents and cardiac antiarrhythmia drugs and recognition and treatment of adverse reactions to these substances

     7.       Recognition and treatment of cardiac arrhythmias associated with CAS

     8.       Technical aspects of performing CAS

     9.       Recognition of any cerebrovascular abnormality or complication related to the CAS procedure

     10.       Postprocedural patient management, particularly the recognition and initial management of procedure complications

Maintenance of competence requires continuing activity including

1. Regular performance of sufficient numbers of neurovascular procedures to maintain success and complication rates as outlined below

2. Participation in a quality improvement program that monitors these rates

3. Participation in courses that provide continuing education on advances in CAS

4. Continuing education should be in accordance with the ACR Standard for Continuing Education

V. SPECIFICATIONS OF THE PROCEDURE

A. Technical Requirements

There are several technical requirements that are necessary to ensure the safe and successful performance of CAS. These include adequate clinical facilities, angiographic and monitoring equipment, and support personnel. The minimal facility requirements are

1. An angiographic suite with sufficient space to allow positioning of patient-monitoring equipment and anesthesia equipment, while leaving adequate room for the circulating staff to move without contaminating the sterile field

2. A high-resolution image intensifier and imaging chain with the ability to acquire and store images digitally; imaging and recording must be consistent with the as low as reasonably achievable (ALARA) radiation safety guidelines

3. Immediate access to computed tomography or magnetic resonance imaging to allow evaluation of any suspected complication (eg, intracranial embolization)

4. Adequate physiologic monitoring equipment for use during and after the procedure, including equipment for cardiopulmonary resuscitation and temporary cardiac pacing

B. Emergency Support

There should be prompt access to medical, surgical, and interventional personnel and resources needed for management of medical or surgical complications.

C. Patient Care

1. Preprocedural care

      

   •    a. The history and indications for the procedure must be recorded in the patient’s medical record; relevant medications, allergies, and bleeding disorders should be noted

   •    b. The vital signs and physical (general and neurologic) examination must be documented

   •    c. Neurologic assessment must include documentation of the National Institutes of Health Stroke Scale (NIHSS) (140)

2. Procedural care

      

   •    a. Vital signs should be obtained and recorded at regular intervals during the course of the procedure

   •    b. Cardiac rhythm should be monitored continuously

   •    c. Intravenous access must be available for administration of fluids and drugs

   •    d. If the patient is to receive conscious sedation, pulse oximetry must be used; administration of sedation should be in accordance with the ACR Standard for Conscious Sedation; anesthesia personnel, a registered nurse, or other appropriately trained personnel should be present and have primary responsibility for monitoring the patient; all medication doses and times should be recorded

   •    e. Neurologic deterioration should be documented and quantified by the NIHSS

3. Postprocedural care

      

   •    a. A procedure note must be written in the patient’s medical record summarizing the procedure, any immediate complications, and the patient’s status at the end of the procedure; this information should be communicated to the referring physician as soon as possible; the note may be brief if the formal report will be dictated and available the same day

   •    b. All patients should be carefully observed during the postprocedure period; the patient’s vital signs and neurologic examination, along with the status of the puncture site and the peripheral pulses should be monitored at regular intervals by a nurse or other qualified personnel

   •    c. The physician performing the procedure or a qualified designee (physician or nurse) should evaluate the patient after the initial postprocedure period; these findings should be recorded in a progress note in the patient’s medical record; the physician and/or designee should be available for continuing care before and after the patient’s discharge from the hospital

   •    d. Neurologic assessment must include documentation of the NIHSS

VI. EQUIPMENT QUALITY CONTROL

The facility must have documented policies and procedures for monitoring and evaluating the effective management, safety, and proper performance of imaging and interventional equipment. The quality control program should maximize the quality of the diagnostic information. This may be accomplished as part of a routine preventive maintenance program.

VII. DOCUMENTATION

VIII. THRESHOLDS, SUCCESS AND COMPLICATION RATES

There is insufficient information to define technical success scientifically. For extremity and renal angioplasty, technical success requires less than 30% diameter residual stenosis by angiography and may require improvement in transstenotic pressure gradient (143,144). In the coronary literature, technical success for balloon angioplasty and stent placement had originally been defined as 20% relative improvement with a decrease in stenosis to less than 50%, but it has recently been revised to a decrease in stenosis to less than 20% (119,120). However, unlike extremity, renal, or coronary stenoses, carotid stenoses are very rarely symptomatic due to hemodynamic compromise. Rather, symptoms arise from embolization from a carotid plaque. It is unknown what degree of correction of carotid stenosis is necessary to reduce the risk of embolization, but removal of the embolic source is fundamental. It is possible that in the attempt to more completely eliminate residual stenosis by full balloon dilation, additional emboli may be produced during the procedure that could cause a higher risk of procedure complications. Alternatively, leaving a higher degree of residual stenosis may lead to a higher rate of late restenosis, which at this time is of uncertain clinical significance. Some carotid stent placement trials have defined technical success as residual stenosis of less than 30% (Yadav J, presented at the American Heart Association Scientific Sessions, Chicago, November 2002). Others have used a definition of residual stenosis of less than 50% (Eles G, The ARCHeR Trial, presented at the SIR Annual Scientific Meeting, Salt Lake City, UT, March 2003). In the absence of definitive scientific evidence, technical success in this document is arbitrarily defined as stent placement resulting in improvement of the stenosis by 20% or more with a final residual stenosis of less than 50% with NASCET measurement criteria. Some practices may prefer to use a lesser degree of residual stenosis as their desired endpoint for technical success.

As with many endovascular and surgical techniques, there is a learning curve associated with CAS. Complications will be more frequent when the procedure is performed by less experienced practitioners. This phenomenon is also recognized with the performance of CEA as well as coronary intervention. To account for the level of physician experience, an ad hoc committee of the AHA Stroke Council (145) proposed that a “beginning surgeon be assigned 100 trouble-free cases as a theoretical statistical basis.” For example, 75 cases would be added proportionately by indication categories to a beginning surgeon’s 25 cases to form a statistical basis of 100 total cases. The number of trouble-free cases is decreased by the number of real cases performed until the practitioner has actually performed 100 cases. With this system, a new physician would be considered to have a 5% complication rate, rather than 50%, if he or she had complications with five of the first 10 cases. This concept appears to be a valid method to account for physician inexperience. Because we have recommended relatively high thresholds (see Table 3) for the complications associated with CAS, the number of trouble-free cases assigned to a new physician should be less than the 100 cases used for evaluation of CEA. Otherwise, excessive complications might continue without triggering a review. For the performance of CAS, 30 trouble-free cases will be assigned (in both the asymptomatic and symptomatic patient categories) to new physicians for initial statistical analysis that will be performed as described in the AHA document.

Previous reports of experience with CAS have described complications, particularly neurologic, in an inconsistent and nonstandardized fashion. We recognize the need for more detailed, clinically relevant, and uniform outcome measures. Both the duration and severity of neurologic complications are important. The necessity for significant postoperative interventions, such as emergency thrombolytic therapy, is also thought to be important. However, defining precisely what would constitute a “significant” posttreatment intervention would be difficult, as would reporting and analyzing all such interventions. Use of the NIHSS facilitates rapid and uniform assessment of neurologic complications. In addition, the NIHSS may serve as a reasonable surrogate measure for significant posttreatment interventions. The rationale for using the NIHSS for this purpose is that small increases in the NIHSS are thought to be much less likely to result in significant interventions, including repeated angiography and thrombolytic therapy. Therefore, adoption of the NIHSS as a standard outcome measure will allow uniform assessment of complications and approximate the incidence of significant postoperative interventions. Differentiation between outcomes and complications in patients with asymptomatic versus symptomatic arterial stenoses is critical. The natural history of the two groups of patients differs dramatically, with much lower risk of stroke in asymptomatic patients. As with CEA, the risks associated with CAS appear to be lower in asymptomatic patients and the risk-to-benefit ratio for CAS appears to be significantly different for asymptomatic versus symptomatic patients.