Natural history of progression of carotid artery stenosis
Al Adas Z, Lin J, Nypaver T, Weaver MR, Shepard AD, Chau LC, Miller D, and Kabbani L. Natural history of progression of carotid artery stenosis. J Vasc Surg 2017; 65(6):50S.
J Vasc Surg
Objectives: Ipsilateral carotid artery stenosis has been reported as the cause of 10% to 20% of ischemic strokes. The rate of progression of carotid artery stenosis is not clear in the literature, and uncertainty exists regarding the optimal frequency of ultrasound examinations for surveillance of untreated internal carotid artery stenosis. This study was designed to define the natural progression of carotid artery stenosis. Methods: The vascular laboratory database at our tertiary care referral center was retrospectively analyzed for all carotid duplex studies performed between January 2004 and June 2014. Patients had to have at least two carotid studies more than ± months apart to be included in the study. Every carotid artery was considered as an individual case. Carotid arteries were grouped by degree of stenosis: Grade 1, no plaque up to 20% stenosis; grade 2, 20% to 49% stenosis; grade 3, 50% to 69% stenosis; grade 4, 70% to 90% stenosis; and grade 5, 90% to 99% stenosis. Progression was defined as an increase by any grade of stenosis. Patient demographics and comorbidities were analyzed for risk factors. Data analysis was conducted using SPSS 22.0 software (IBM Corp, Armonk, NY). Results: During the study period, 43,314 carotid arteries were imaged; of these, 6190 met the inclusion criteria. Average follow-up time was 43 months; average time between examinations was 29 months. Average age was 70 years, 52% were women, 82.5% had grade 1 or 2 stenosis, and 17.5% had grade 3, 4, or 5 stenosis. Only 2.6% of grade 1 arteries and 15% of grade 2 arteries progressed to grade ≥3. Of those carotid arteries with grade 3, 4, or 5 stenosis, 174 (16.2%) progressed to a higher grade, and average time to progression was 8 years. For grades 3, 4, and 5 stenosis, male sex (P =.023), young age (P =.001), and atrial fibrillation (P =.002) were independent risk factors for progression. Conclusions: This study documents a relatively slow progression rate for carotid disease. This result calls into question the utility of annual surveillance imaging in patients with carotid stenosis. Clinical criteria are needed to define a high-risk group of patients who might benefit from more frequent imaging.