Physicians who have little experience with technically demanding carotid artery stenting have alarmingly higher rates of 30-day mortality than more seasoned operators, according to a study that reviewed 24,701 procedures in Medicare beneficiaries.
Additionally, more than 70% of the operators performed fewer than six procedures annually, a level of experience associated with the highest, 2.5%, risk of patient death.
Patients of operators who performed 6 to 11 procedures a year had a 1.9% 30-day mortality, 12-23 procedures had a 1.6% mortality and patients of operators with 24 or more procedures had a 1.4% mortality, indicating a treacherous learning curve at the patient's expense.
For some reason, novice operators were less likely to use an embolic protection device, which is a filter or balloon placed inside the artery to prevent particles from escaping and causing neurological damage.
The report by Brahmajee K. Nallamothu, MD, of the University of Michigan Medical School in Ann Arbor was published Wednesday in the Journal of the American Medical Association.
"Overall, 461 patients (1.9%) died within 30 days of their procedure and 1,173 patients (4.8%) did not receive an embolic protection device," the Nallamothu and colleagues wrote. "We identified an additional factor that may be contributing (to higher rates of 30-day mortality): limited operator experience with carotid stenting as the procedure has disseminated into routine clinical practice.
"Indeed, we found that fewer than 1 in 8 operators had annual operator volumes of 12 procedures or more during the study period."
Nallamothu noted that unlike other types of procedures that have been performed for longer periods, there is no professionally agreed upon standard for training requirements on the number of stenting procedures one must do under supervision before becoming the primary practitioner on the case.
Asked what he thinks the training requirements might be, he wrote in an e-mail that "no one knows for sure," although a coalition consisting of the Society for Cardiac Angiography, the Society for Vascular Medicine and the Society for Vascular Surgery suggests that a minimum of 25 procedures is required, with half as primary operator.
Use of carotid artery stents, designed to prevent stroke, was approved by the U.S. Food and Drug Administration in 2004 as a less invasive alternative to carotid artery surgery or endartarectomy. Since then, use of the practice has more than doubled.
It can be done without general anesthesia, and operators include cardiologists, radiologists, and general surgeons.
In an accompanying editorial, Ethan Halm, MD, of the Departments of General Internal Medicine and Clinical Sciences of the University of Texas Southwestern Medical Center in Dallas, noted that in clinical practice, mortality rates seem to be more than twice the mortality rate in CREST, the Carotid Revascularization Endartarectomy vs. Stenting Trial that led to the procedure's approval.
"The mortality rates even among the most experienced Medicare operators in the study by Nallamothu et al were substantially higher than those in CREST and postapproval studies," Halm wrote. "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 mortality rates caused by clinicians' learning curve, Halm wrote, place policy makers "at a fundamental crossroads regarding carotid artery stenting (CAS)."
"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 CEA (carotid endartarectomy) and percutaneous coronary interventions."
Halm also called for the Centers for Medicare & Medicaid Services to restrict reimbursements and impose requirements for credentialing operators and facilities, and mandatory reporting of audited 30-day death and stroke rates. He also suggested that the new Patient-Centered Outcomes Research Institute take on the procedure to "clarify the indications, appropriateness, and outcomes of CAS in both ideal and real-world practice."