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EDITORIAL COMMENT

Credentialing Operators forCarotid Artery StentingAccepting the Occasional “Bad Apple” orInsisting on Airline Industry “Proficiency”*

Gary S. Roubin, MD, PHD

SEE PAGE 1307

I n the coming months, this nation will launch a

landmark study to further investigate stroke pre-vention strategies for asymptomatic patients

with high-grade carotid stenosis. The National Insti-tute of Neurological Disorders and Stroke (NINDS)CREST-2 (Carotid Revascularization EndarterectomyVersus Stenting Trial-2) is a prospective multicenterrandomized comparison of state-of-the-art contem-porary medical therapy versus elective revasculariza-tion. Because the NINDS recognizes 2 complementaryand equally safe and effective methods of revascular-ization—carotid stenting (CAS) and carotid endarter-ectomy—the trial will have parallel paths comparingeach revascularization method to best medicaltherapy.

The investigators have set the bar high in definingbest medical therapy. They have rightly designed abest medical therapy protocol to reflect an idealapproach to medical care that all expect to become astandard in future years. This “5 Starr” medicalregimen requires rigorous pharmacological controland monitoring of hypertension, blood lipids, dia-betes, and antiplatelet therapy. In addition, rigorousprotocol-driven lifestyle modifications, includingcessation of tobacco use, weight reduction, and ex-ercise programs, will be instigated and monitored.

Needless to say, for this difficult scientificendeavor to produce meaningful results, the

*Editorials published in JACC: Cardiovascular Interventions reflect the

views of the authors and do not necessarily represent the views of JACC:

Cardiovascular Interventions or the American College of Cardiology.

From the Cardiovascular Associates of the Southeast, Birmingham,

Alabama. Dr. Roubin has received royalties from Cook Medical Inc.; has

equity interests in Essential Medical Inc.; and consults for The Medicines

Company.

revascularization arms will need to be conductedwith equal rigor.

Carotid endarterectomy, in standard practice formore than 50 years, enjoys the privilege of full reim-bursement from the Centers for Medicare andMedicaid Services (CMS) and operator volumesremain adequate. Accordingly, the task of the CREST-2 surgical management committee to qualify experi-enced and creditable surgical operators should notbe a challenge. The opposite exists for the stentinginterventional management committee (IMC). Despitethe excellent comparative outcomes for stenting inthe CREST trial, CMS has determined not to cover thisless invasive and less traumatic alternative to carotidendarterectomy. Accordingly, the number of stentingoperators with a creditable current experience is“sparse.” As CREST-2 embarks on the important jobof trial site initiation, the stenting IMC is taskedwith the challenging mission of identifying operatorsthat will do credit to the trial with “5 Starr” stentingoutcomes.

The CREST IMC has requested prospective CREST-2stenting operators to submit information on totalvolume experience and detailed records on their last25 consecutive cases. The challenge in identifying theprospective “bad apple” from the safe and creditableoperator (commercial airline pilot analogy) hasproved enormously difficult. How many errors arepilots permitted before being grounded? From a sta-tistical perspective, the number of cases submitted istoo small to make “meaningful” evaluations on eventrates in isolation.

The paper by Shishehbor et al. (1) in this issue ofJACC: Cardiovascular Interventions is both timely and

J A C C : C A R D I O V A S C U L A R I N T E R V E N T I O N S V O L . 7 , N O . 1 1 , 2 0 1 4 RoubinN O V E M B E R 2 0 1 4 : 1 3 1 8 – 9 Carotid Artery Stenting

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helpful in guiding the CREST-2 IMC in its mission ofevaluating operator experience and outcomes. Theinvestigators attempted to improve our understandingof operator-related factors on technical performancefor CAS by undertaking a comprehensive analysis ofpreviously reported and new metrics that might in-fluence outcomes. This well-conducted analysis of alarge cohort of operators and procedures (5,240 pa-tients) in the U.S. Food and Drug Administration—sponsored, prospective CHOICE (Carotid Stenting forHigh Surgical-Risk Patients; Evaluating OutcomesThrough the Collection of Clinical Evidence) registryfocused on a specific combination of an embolic pro-tection device (EPD) and stent. They excluded otherknown confounding effects using the comprehensivedatabase of baseline factors and a multivariable logis-tic regression analysis. High-volume experiencedoperators have for many years taught that shorteningEPD dwell times may be a way of avoiding adverseevents during the carotid stent procedure. In thisstudy, the investigators hypothesized that the EPDdwell time would be a measure of good technical per-formance and a predictor of good outcomes. Cardiol-ogists (p<0.001) alongwith operatorswith longer timeinterval from first CAS (p < 0.001) had reduced EPDdwell times (technical performance). Increased timeinterval between CAS was the only independent pre-dictor of increased 30-day adverse events. Impor-tantly, prolonged EPD dwell time was also associatedwith 30-day adverse events.

How might the CREST-2 IMC and others evaluatingoperator performance for CAS use this information?Total experience (likely reflected in this analysis bytime from first CAS) has been previously demon-strated as a marker of low event rates, and now wecan add 2 additional metrics—the average intervalbetween submitted procedures and EPD dwell times.It should come as no surprise that operators per-forming a given procedure with frequency would beproficient at their work. But what of EPD dwell times?From the outset of the work with the development ofEPD, it was known that the shear forces associated

with filtering blood through the micro pores of thedevices was associated with the precipitation andadherence of fibrin deposits to the filters. Thisis likely a time-related (and device design-related)phenomenon. There are numerous reports of filtersoccluding during prolonged stenting procedures,with this “fibrin clogging” probably being the primaryevent.

There are numerous other potential factors thatmay make short EPD dwell times a measure of bothproficiency and safe outcomes. The cognitive skill ofthe operator in understanding optimal patient selec-tion immediately comes to mind. Even after “strug-gling” to deploy an EPD in the tortuous, calcified longcomplex lesion (which should not be treated withstenting), subsequent stent placement, dilation, andEPD retrieval are challenging and may prolong theEPD dwell time. In addition, the intervening increasedmanipulation may be associated with increasedembolization. Then there is the facile, expeditioustechnique! Experienced assistants and the experi-enced team ready to assist with timely placement ofthe stent may also play a role. Limiting contrast runs(also a source of micro bubbles), minimizing post-dilation of the stent (the most potent source ofembolic particles), and experience in knowing how tointerpret the post-stent angiographic result are alsoreflected in shorter EPD dwell times.

The CREST-2 executive and IMC committees, incollaboration with the NINDS, have approached CMSto establish a CREST-2 registry that will facilitate thecurrent stenting experience of potential operators. Inaddition to scrutinizing operator procedural tech-nique and outcomes, we will now have 2 additionalmetrics (frequency of procedures and EPD dwelltimes) to aid us in selecting appropriate operators forthe trial.

REPRINT REQUESTS AND CORRESPONDENCE: Dr.Gary S. Roubin, Cardiovascular Associates of theSoutheast, 3980 Colonnade Parkway, Birmingham,Alabama 35243. E-mail: garyroubin@aol.com.

RE F E RENCE

1. Shishehbor MH, Venkatachalam S, Gray WA,et al. Experience and outcomes with carotid arterystenting: an analysis of the CHOICE (CarotidStenting for High Surgical-Risk Patients;

Evaluating Outcomes Through the Collection ofClinical Evidence) study. J Am Coll Cardiol Intv2014;7:1307–17.

KEY WORDS carotid stenting outcomes,CREST, embolic protection devices