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03-10-2011 | Stroke | Article

Operator inexperience hits CAS outcomes in ‘real-world’ practice


Free abstract

MedWire News: Patients undergoing carotid artery stenting (CAS) outside the setting of a clinical trial are at an increased risk for mortality if the operator is inexperienced, shows an analysis of Medicare data.

In an editorial accompanying the report in JAMA, Ethan Halm (University of Texas Southwestern Medical Center, Dallas, USA) warned: "Relatively high complication rates in real-world practice would substantially reduce and perhaps completely eliminate any long-term expected benefit of revascularization, especially among asymptomatic patients who have much less to gain from the procedure."

The 30-day mortality rate in the US-based randomized Carotid Revascularization Endarterectomy vs Stenting Trial (CREST) was 0.7%, and the reported mortality rate in postapproval CAS studies is about 1.0%.

But in the current study, by Brahmajee Nallamothu (University of Michigan Cardiovascular Center, Ann Arbor, USA) and colleagues, the overall 30-day mortality rate of 24,701 procedures in Medicare claimants was twice that, at 1.9%.

The procedures were performed by 2339 operators, 1792 of whom began performing CAS only after the national coverage decision from the Centers for Medicare & Medicaid Services. These new operators had patient mortality rates of 2.3% when performing their first to 11th procedures, compared with 1.4% from the 12th procedure onward. After accounting for confounders, patients had a 1.7-fold increased risk for dying if their operator was early versus late in their CAS experience.

Annual case volume, reflecting how often an operator performs CAS, also affected patients' mortality risk. Patient mortality rates fell in line with increasing annual operator volumes, from 2.5% to 1.9%, 1.6%, and 1.4% for fewer than 6, 6-11, 12-23, and 24 or more procedures per year. Patients' mortality risk was increased 1.9-fold if they were treated by an operator with fewer than 6 versus 24 or more cases per year.

Operators' median annual volume was just 3.0 cases per year, and only 11.6% of operators performed 12 or more CAS procedures per year.

In his editorial, Halm noted that a high proportion of patients in the study were very old and asymptomatic, but with a high comorbidity burden, in other words, a group that would derive little benefit from stenting.

"A procedure performed in a patient who would not be expected to benefit from it is inappropriate and wasteful regardless of how skilled the operator or how low the complication rate," he said.

Halm also highlighted the point that improved medical management of patients with asymptomatic carotid stenosis has reduced stroke rates even without intervention, with reported rates now at 0.5-1.0%.

"The risk is so low that it may not be possible to demonstrate any benefit with revascularization given its periprocedural complications," he said.

Halm warned: "Without careful policies to ensure appropriate use and dissemination of CAS, the procedure may be misused and overused, as was seen in early in the diffusion of [carotid endarterectomy] and percutaneous coronary interventions."

By Eleanor McDermid

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