Elderly patients treated with carotid artery stenting (CAS) faced a higher risk of stroke with increasing age compared with patients treated with carotid endarterectomy (CEA), according to a study published Oct. 6 in the online issue of Stroke. Based on the results, the authors recommend physicians take patient age into consideration when choosing a treatment for carotid stenosis.
Jenifer H. Voeks, PhD, at the University of Alabama in Birmingham, Ala., and colleagues conducted an extended investigation of the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) to assess the role of age on efficacy of the two procedures and to assess factors that may influence age-related risk differences. The analysis was based on CREST, a randomized clinical trial that enrolled 1,321 symptomatic patients with high-grade carotid stenosis and 1,181 asymptomatic patients with high-grade carotid stenosis.
The researchers noted that patients in their 80s were excluded during CREST after a high risk of stroke was observed, but that they continued to be included in randomization to assess for risks from CEA. Consequently, their current study was based on only lead-in data that was blinded and randomized.
The authors conducted proportional hazards analysis to evaluate the impact of age on the relative efficacy of CAS and CEA, and the impact of age on risk within the two treatment groups. Their analysis found the risk for stroke increased with age in the CAS group but was little changed in the CEA group. Patients treated with CAS had a 1.76 times increase in the risk of a stroke event with each 10-year age increment. Patients treated with CEA had no difference in risk across the age spectrum.
“The risk of the two procedures is approximately equal at age 70 years, with CAS showing superiority in younger patients, and there is an increasing benefit for CEA in older patients,” they wrote. “The point of equal risk is at age 64 years.”
In a CAS-only mediation analysis, they found no evidence that differences in factors such as the prevalence of hypertension, diabetes or dyslipidemia, differences in lesion characteristics or procedure duration contributed to age-related risk differences. The researchers also noted a modest effect from total fluoroscopy time, though.
“[T]he degrees of arterial tortuosity or lesion calcification were not available in the data set and could contribute to increased CAS events in the elderly,” they suggested. “We hypothesize that the risk of embolization during CAS is increased during navigation of tortuous extracranial arteries. … Consistent with this hypothesis, we observed that the elderly required longer fluoroscopy time for CAS.”
They added that while CREST was a large cohort that represented a broad range of age groups, their initial projection of events such as strokes proved to be smaller than actually occurred. Despite that limitation, they argued that their analysis showed that there was a difference in efficacy of CAS compared with CEA related to patient age, primarily attributed to strokes. Given the increased risk of stroke at older ages for CAS, they concluded that age should be factored into treatment decisions for carotid stenosis.