Competencies for Endovascular Specialists Providing CLTI Care

The writing committee believes that technical proficiency for endovascular operators is improved by procedural volumes and experience. However, given limited data quality, heterogenous effect sizes, and differential and evolving findings, the writing committee also believes there is an absence of evidence to clearly define a procedural volume threshold whereby competence in endovascular interventions for CLTI is manifest. As such, the group has elected not to recommend a requisite minimal procedural volume at this time.

Published training statements from a variety of specialty societies have suggested that physicians perform a minimum of 100 diagnostic peripheral angiograms in order to display competence. There is less consistency in recommended interventional procedure volumes, but most societies recommend a minimum of 50 to 80 peripheral interventions, the majority of which should be arterial in nature. None of the recommendations address endovascular interventions for CLTI specifically, nor do they attempt to account for the varying degrees of complexity inherent to lower extremity arterial interventions based on lesion phenotype (e.g., stenosis versus calcified chronic total occlusion), segment (e.g., aorto-iliac versus tibial), and patient characteristics.

Better evidence to help formulate training guidelines and allow a systematic approach to endovascular competency will be a key multispecialty priority in coming years. For example, training programs could have their trainees log CLTI procedures, stratified by segment and complexity, and submit these data to a central repository to accurately quantify the number and types of procedures that endovascular trainees are performing in CLTI patients during their training programs. Similar processes, though not specific to CLTI, already exist for some procedural specialties. One could envision such an endeavor being a collaborative effort amongst medical organizations who support the educational endeavors of endovascular specialists.

National CLTI registries may also prove beneficial. While existing registries such as the Society of Vascular Surgery Vascular Quality Initiative (SVS VQI) collect procedural and outcome data on many CLTI patients, the ability to account for trainee involvement in procedures is currently limited. Modifications to data collection instruments that incorporate trainee participation could afford opportunities to generate volume thresholds for endovascular CLTI specialists.

Traditional training statements discuss institutional requirements and resources necessary for learners to obtain the requisite skillsets to become competent in their specialty of interest. Care of the CLTI patient involves multiple environments including urgent care facilities, outpatient longitudinal clinics, inpatient wards, and procedural areas such as office-based laboratories, angiography suites, and operating rooms. Additionally, areas providing ancillary services like vascular laboratories and wound care centers contribute significantly to the overall management of this population. As such, it may be best to conceptualize the environment of developing endovascular specialists as a CLTI care system rather than an institution. In this sense, the care system functions as a comprehensive habitat where all aspects of CLTI care can be offered to optimize chances of best patient outcomes. This concept has been previously described and emphasizes the multidisciplinary care mandated for this unique population.

Elements of the CLTI care system that should be available to support competency acquisition include outpatient clinics, diagnostic testing facilities (e.g., accredited noninvasive vascular laboratory), and procedural areas. In regard to clinics, many CLTI patients need urgent evaluations for wounds, infections, ischemic rest pain, and cardiovascular comorbidities. As such, clinic infrastructure should be able to accommodate CLTI patients quickly and efficiently, avoiding unnecessary delays that may jeopardize patient care. Collaboration with podiatry and wound care centers is of paramount importance, and institutions should have established relationships to these services to facilitate timely evaluation and management of CLTI patients before and after revascularization. Many patients may lack the necessary resources or social support to undergo the in-person clinical evaluations. In these scenarios, use of telemedicine service may be a useful mechanism to combat these barriers to care.

Noninvasive vascular testing is of obvious importance in CLTI. Substantial variation in pre-procedural testing occurs in patients with CLTI based on patient characteristics, resource availability, and operator biases. At a minimum, the ability to obtain imaging with either CT, MR, or DUS should be available, though many patients may not be candidates for contrast-based studies due to the presence of renal dysfunction. A high-quality, Intersocietal Accreditation Commission-accredited vascular laboratory is necessary to perform arterial physiologic testing, perfusion assessment, and associated venous studies that may be necessary in CLTI patients. In particular, acknowledging the limitations of the ABI in CLTI, objective markers of wound healing such as toe pressures and TCPO2 are valuable in the care of individual patients and may facilitate more rapid and efficient treatment decisions. The laboratory should offer comprehensive vascular testing to facilitate the acquisition of the Registered Physician in Vascular Interpretation credential (RPVI) for learners in these respective programs.

Procedural areas should be equipped with imaging systems capable of performing high-quality digital subtraction angiography (DSA). Supporting technologies (e.g., ultrasound guidance) should be available to assist with standard arterial and alternate access. Endovascular interventions will span from the aorta to the distal tibial and pedal circulations. As such, the procedural laboratories should have a full complement of wires, catheters, and balloons compatible with 0.014”, 0.018”, and 0.035” systems. Niche devices including re-entry catheters, crossing devices, cutting or scoring balloons, and atherectomy devices should be available since they may be needed to treat the complex disease subsets encountered in CLTI. Intravascular imaging (e.g., IVUS) has been associated with improved limb salvage rates,47 and may be helpful in optimizing technical outcomes. The procedural area should be equipped with devices to manage emergent complications, and if the facility is not within a hospital setting, systems should be in place to rapidly triage and transfer patients to acute care facilities when such complications arise.

There are several avenues for acquiring the necessary clinical, didactic, and hands-on training for CLTI. The intensity of training and clinical exposure varies based on the pathway chosen: formal training or independent courses in a post-training practice.

Formal training programs
Post-graduate, traditional training programs can take form in one of three different training tracks: vascular surgery (VS), interventional cardiology (IC), or interventional radiology (IR). Aside from the hands-on procedural training for CLTI, residents and fellows also undergo clinical training focusing on patient management, wound care, and certification for vascular interpretation as a part of these programs.

Vascular surgery training can be obtained in either a traditional vascular fellowship (5+2) program or an integrated vascular residency (0+5) program. In the traditional program, trainees undergo general surgery training for 5 years, followed by a 2-year sub-specialty fellowship training in vascular surgery. The integrated program, approved in 2006, allows a more focused sub-specialty training for a longer period. Both training paradigms have yielded positive training experiences and desired practice placement.

Interventional cardiologists complete internal medicine residency and general cardiology fellowship, which are 3 years each in duration. Interventional cardiology fellowship has traditionally been a 1-year training experience with emphasis on coronary intervention. Many 1-year programs do offer peripheral training as well, and depending on the program, some do offer exposure to opportunities to acquire additional skillsets such as the RPVI certification. Moreover, vascular medicine is a requisite component of general cardiology fellowship, and most interventional cardiology fellows will have completed multiple months of vascular medicine rotations prior to beginning procedural fellowships. Given the complexity of CLTI, interventional cardiology fellows who plan to focus on CLTI should strongly consider pursuing advanced endovascular training, such as an additional year of peripheral vascular fellowship.

With the advent of advanced endovascular, structural heart, and increasingly complex coronary interventions, 2-year interventional cardiology or advanced endovascular fellowships are now becoming common in many academic centers. Many of these advanced programs allow for the acquisition of non-procedural skillsets and fulfill criteria to become board-eligible in vascular medicine.

Interventional radiology training is currently available via three routes. All trainees start with 1 year of a clinical internship. Pathways thereafter diverge and can include one of the following: (1) 3 years of diagnostic radiology with 3 months of interventional radiology, followed by 2 years of dedicated interventional radiology training (integrated IR residency); (2) 4 years of diagnostic radiology, which includes at least 3 months of interventional radiology, followed by 2 years of dedicated interventional radiology training (independent IR residency); (3) 4 years of diagnostic radiology with 12 months of interventional radiology and 500 image-guided procedures, followed by 1 year of interventional radiology training (early specialization).

The selected training path across each of these disciplines will depend upon individual trainee goals and career trajectory, as all of these specialties have non-endovascular components as well. Specifically, a vascular surgery practice will have a component of open surgery, an interventional cardiology pathway will incorporate coronary interventions and potentially structural heart interventions, and an interventional radiology track will also include diagnostic film interpretation and non-vascular interventions.


Post-training courses
For those already in clinical practice, there are industry-sponsored opportunities to travel to high-volume centers for endovascular courses. These programs are typically composed of one to two days of intensive cases to allow demonstration in various aspects of endovascular procedures. Topics may include alternative access, ultrasound-guided access, crossing techniques, calcium modification, drug delivery, and device-specific usage. Simulations, proctored cases, and “double-scrubbing” with experienced operators are additional ways for established practitioners to obtain hands-on experience. Compared to formal training, post-training independent learning has the advantages of exposure to endovascular practice variability throughout the country and being able to “learn on the job” without interruption of one’s established clinical practice. Disadvantages include a relatively minimal hands-on experience compared to the full immersion offered by traditional training pathways, lack of formal guidance on long-term CLTI patient clinical management before and after endovascular procedures, absence of standardization of training techniques, and significant risk of device-specific bias.


Lifelong learning
The key for long-term success is engagement in lifelong learning through local, national, and international conferences, to continue to share ideas across the wide spectrum of endovascular practices, and to stay up to date on advancements in care in this complex patient population. Given the importance of technological innovation in endovascular therapies, industry-supported training programs will remain an important source of education for CLTI operators. Educational organizations are uniquely positioned to develop CLTI-specific continuing medical education (CME) content that providers may access to enhance performance.

The common goals of all specialties engaged in the care of CLTI patients are to optimize quality of life, reduce cardiovascular morbidity and mortality, and eradicate preventable amputation. CLTI will continue to be managed by multiple specialists from diverse training backgrounds, and as such, standardizing expected competencies for endovascular specialists is a necessary step to ensure that patient-centric and evidence-based therapy is delivered. The framework presented in this document is a starting point to enable training programs, professional medical societies, and other entities to develop curricula to optimize skillsets for clinicians focusing on this clinical niche. Ultimately, through the identification of common needs spanning across multiple endovascular specialties, such an effort may spark collaborative inter-disciplinary education efforts, and ultimately enhance the care that this population so desperately needs.