Comparison of Carotid Atherosclerosis between Patients at High Altitude and Sea Level: A Chinese Atherosclerosis Risk Evaluation Study

Objectives: To investigate the differences in characteristics of carotid plaques between patients Xining at high altitude and Jinan at sea level using magnetic resonance (MR) imaging. Methods: Subjects were recruited from a cross-sectional, observational, multicenter imaging study of CARE-II study. Forty-nine (mean age 63.3 ± 12.0 years, 33 males) and 51 (mean age 64.5 ± 12.0 years, 34 males) patients were recruited from a site located in a high altitude region and a site located near sea level, respectively. All patients underwent multicontrast MR vessel wall imaging for carotid arteries on 3.0 T MR scanner. The carotid plaques features were compared between 2 patient groups. Results: Compared with patients at sea level, those at high altitude had significantly greater lumen area (58.5 ± 17.8 mm² versus 50.0 ± 19.6 mm², P = .008), smaller maximum normalized wall index (48.6% ± 14.2% versus 57.8% ± 16.3%, P = .002), and smaller percentage volume of calcium (0.9% versus 5.6%, P < .001) in the symptomatic carotid artery. After adjustment for clinical risk factors including age, sex, systolic blood pressure, LDL-C, and statin use, these differences in plaque morphology and composition remained statistically significant. After further adjustment for normalized wall index as a measure of plaque burden, percentage volume of calcification was still significantly smaller in patients at high altitude area than that in patients at sea level area (P = .047). Conclusion: Symptomatic subjects from a high altitude area have lower plaque burden and less calcification in the carotid artery compared to those from an area near sea level.