Abstract
BACKGROUND: It is unclear to what extent the cardiac cycle influences carotid intima-media thickness CIMT values, especially in individuals with major Cardiovascular Risk Factors (CVRF). The authors analyzed CIMT variability across the cardiac cycle using baseline data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). METHODS: The authors analyzed data from 9546 ELSA-Brasil participants, aged 35 to 74 in six Brazilian cities. CIMT image acquisition was ECG-gated during three cardiac cycles (70 to 90 frames). The authors calculated the Coefficient of Variation (CV), range, and interquartile range to assess variability using frame-by-frame data. In addition, the authors stratified the sample according to the presence of five major CVRFs: hypertension, diabetes, dyslipidemia, smoking, and family history of premature CVD. RESULTS: The mean age of the sample is 51.5 years (56% women). CIMT variability was higher in individuals with major CVRF, except for a family history of premature CVD. As expected, variability was higher in measurements of the near wall (CV: 5.8% and 4.9% for left and right CCA, respectively) than those of the far wall (CV: 2.1% for both CCA). A significant positive trend was observed between variability measurements and the number of major CVRFs (all p < 0.001). DISCUSSION: The authors found a significant CIMT variability across the cardiac cycle in a very large sample. The magnitude of this phenomenon is more important among individuals with CVRFs. CIMT acquisition protocols must consider the effect of the cardiac cycle to improve risk estimation and reproducibility.