NEW YORK (Reuters Health) – While carotid artery stenting (CAS) can be performed safely in different hospital settings by a variety of specialists, both site and operator volumes are important determinants of outcomes, according to study findings reported in JACC: Cardiovascular Interventions for February.

“Prompted by the observation that in multicenter studies many hospital sites were able to perform CAS with few or no adverse events — whereas others produced less favorable outcomes — there was a recognition of the need for a deeper understanding of what specific site and operator factors are associated with better CAS outcomes,” Dr. William A. Gray, at Columbia University, New York, New York, and colleagues explain.

To investigate, they analyzed data from the CAPTURE study in terms of the American Heart Association’s definition of acceptable CAS outcome: that is, a 30-day rate of death or stroke no greater than 3% in asymptomatic non-octogenarian subjects.

The study included 3388 patients that met those criteria out of a population of 5297, who were treated at 180 US hospitals by 459 operators. In the subgroup, the overall rate of death or stroke at 30 days was 2.7%.

The investigators found that 66% of the sites had no deaths or strokes, while the other third had at least one such event. Among those sites, there was an inverse relationship between event rates and patient volume.

There was no evidence that hospital type or geographic location had a significant influence on outcomes.

Similarly, 82% of the individual operators had no death or stroke events. Among the remaining operators, “an inverse relationship between event rates and operator volume was again observed.” This was independent of the operator’s specialty, according to the report.

The researchers calculate from the data that a minimum center volume of 72 CAS procedures is needed to achieve a death or stroke rate below 3%. “This value is higher than what has been suggested in the past or what has served as the threshold for enrolling patients in randomized trials,” Dr. Gray and colleagues point out.

They conclude that the association between volume/experience and outcomes of CAS is important “to establish the experience and training requirements for future trials as a way to eliminate unqualified operators as potential confounders of outcomes.”

Reference:

Influence of Site and Operator Characteristics on Carotid Artery Stent Outcomes: Analysis of the CAPTURE 2 (Carotid ACCULINK/ACCUNET Post Approval Trial to Uncover Rare Events) Clinical Study

J Am Coll Cardiol Intv 2011;4:235-246.