Varying Definitions of Carotid Intima‐Media Thickness and Future Cardiovascular Disease: A Systematic Review and Meta‐Analysis

Abstract

Background Carotid intima‐media thickness (cIMT) has been widely used as a predictor of future cardiovascular disease (CVD); however, various definitions of cIMT exist. This study provides a systematic review and meta‐analysis of the associations between different cIMT definitions and CVD. Methods and results A systematic review of the different cIMT definitions used in prospective cohort studies was performed. The relationships between cIMT of different definitions (common carotid artery IMT [CCA‐IMT], internal carotid artery IMT [ICA‐IMT], combined segments [combined‐IMT], mean CCA‐IMT, and maximum CCA‐IMT) with future stroke, myocardial infarction (MI), and CVD events were analyzed using random effects models. Among 2287 articles, 18 articles (14 studies) with >10 different cIMT definitions were identified and included in our meta‐analysis. After adjusting for age and sex, a 1‐SD increase in CCA‐IMT was associated with future stroke (hazard ratio [HR], 1.32 [95% CI, 1.27–1.38]), MI (HR, 1.27 [95% CI, 1.22–1.33]), and CVD events (HR, 1.28 [95% CI, 1.19–1.37]). A 1‐SD increase in ICA‐IMT was related to future stroke (HR, 1.25 [95% CI, 1.11–1.42]) and CVD events (HR, 1.25 [95% CI, 1.04–1.50]) but not MI (HR, 1.26 [95% CI, 0.98–1.61]). A 1‐SD increase in combined‐IMT was associated with future stroke (HR, 1.30 [95% CI, 1.08–1.57]) and CVD events (HR, 1.36 [95% CI, 1.23–1.49]). Maximum CCA‐IMT was more strongly related than mean CCA‐IMT with risk of MI, and both measures were similarly associated with stroke and CVD events. Conclusions Combined‐IMT is more strongly associated with CVD events compared with single‐segment cIMT definitions. Maximum CCA‐IMT shows a stronger association with MI than mean CCA‐IMT. Further research is warranted to validate our findings and to standardize the cIMT measurement protocol, as well as to explore underlying mechanisms.