Higher-Volume Operators of Carotid Stenting Reap Better Outcomes, Lower Costs

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 Higher annual operator volume of carotid artery stenting (CAS) is associated with a host of benefits—lower postoperative mortality, fewer complications, shorter length of hospitalization, and reduced cost, according to a retrospective database study published online July 3, 2014, ahead of print in the American Journal of Cardiology. 

Apurva O. Badheka, MD, of Detroit Medical Center (Detroit, MI), and colleagues looked at postprocedural mortality and complications in 13,564 patients who underwent CAS between 2006 and 2010 and were included in the Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample.
Mean patient age was 71 years, 60.6% were men, and 75% had hypertension. More than half of CAS procedures (60.3%) were performed in teaching hospitals following an elective admission (69.8%), and the most common primary payer was Medicare/Medicaid (74.6%).  


Symptomatic Patients, Low-Volume CAS Operators Fare Worse

 Rates of postprocedural mortality (0.5%) and complications (8%; including cardiac, vascular, respiratory, neurological, renal, and metabolic as well as need for open heart surgery) were low and relatively steady in the overall population.

In multivariate analysis, female and symptomatic patients had higher rates of postoperative mortality and complications, while procedures with more experienced operators resulted in fewer adverse events (table 1).

Table 1. Predictors of Mortality, Complications after CAS 



95% CI

P Value

Female vs Male



< .001

Symptomatic vs Asymptomatic



< .001

Operator Volume of 5-13 Procedures/Year vs < 5




Operator Volume of 14-68 Procedures/Year vs < 5





  Higher annual operator volume remained an independent predictor of lower postprocedural mortality and complications in 2 subgroups: the highest tertile of annual hospital volume and asymptomatic patients.

Overall, iatrogenic stroke (1.6%) and cardiac complications postprocedure (2%) were rare, and the incidence of vascular (3.7%) and renal complications (0.1%) were minimal with 0.8% requiring transfusion due to postoperative hemorrhage.

Average hospital length of stay was 2.52 ± 0.02 days with a mean cost $14,366. While average length of stay decreased from 2006 to 2010, hospital costs increased, primarily in symptomatic patients. A high burden of comorbidity predicted longer hospital stay and increased the cost of hospitalization by $1,603. Similarly, any postprocedural complication was associated with an average increase in length of stay of 2.48 days (P < .001) and an increase in hospitalization costs of $7,466 (P < .001).

Compared with those who were asymptomatic, symptomatic patients had hospital stays that were on average 1.3 days longer (P < .001) and $3,223 more costly (P < .001).

Higher annual operator volume predicted shorter length of stay (1.11 days shorter for operators with 5-13 annual procedures, 1.17 days shorter for operators with 14-68 cases) as well as reduced hospitalization cost ($2,956 less for operators with 5-13 annual procedures, $2,778 less for operators with 14-68 cases).

Positive Trend for Symptomatic Patients

“Analogous to a subanalysis of the CREST trial, symptomatic patients had significantly higher postoperative mortality and rate of complications in our study even in hospitals with highest annual volume,” Dr. Badheka and colleagues write. “A subset analysis of our study cohort shows a decreasing trend for in-hospital mortality as well as postprocedural complications in symptomatic patients, though it continues to be higher than that observed in asymptomatic patients undergoing CAS.”

Explanations for the trend may include evolving technology and operator experience as a result of increased utilization of CAS since its US Food and Drug Administration approval in 2011 they observe, adding, “Our study results, though not conclusive, should be considered as informative for further research in this field.”

Additionally, the study authors say the operator volume findings parallel other reports in the literature and provide more support for limiting CAS procedures to “physicians in the latter stages of a relatively steep learning curve.”

In an email with TCTMD, Hitinder S. Gurm, MD, of the University of Michigan Medical Center (Ann Arbor, MI), agreed, adding, “Under the current setting, the procedure is best performed by those who have the requisite experience. The volume outcome signal is remarkably strong, and I think patients should ask the physician about the total number of procedures they perform and their complication rates.”

Complications, Cost Argue for Restrictions on Operators

However, Dr. Gurm cautioned that the findings should be interpreted with the caveat that studies based on billing data may underestimate events other than death.

“Having said that, the complication rates that were observed [in symptomatic patients] were high, but stroke and mortality appear to be lower than the threshold of 6%,” Dr. Gurm noted. “For many reasons (chiefly CMS restrictions on reimbursement), the procedure has not been that widely disseminated in clinical practice, and the results reflect a fairly restricted number of procedures.”

Dr. Gurm added that the cost association with low-volume operators is a novel finding. “If one considers both the complications and the cost, the results argue for restricting the procedures to operators who do enough of these and have demonstrated good outcomes,” he commented.


Badheka AO, Chothani A, Panaich SS, et al. Impact of symptoms, gender, co-morbidities and operator volume on outcome of carotid artery stenting (from the Nationwide Inpatient Sample [2006-2010]). Am J Cardiol. 2014;Epub ahead of print.


  •  Dr. Badheka reports no relevant conflicts of interest.
  • Dr. Gurm reports receiving funding from the Agency for Healthcare Research and Quality.

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