Validation of Circumferential Carotid Artery Strain as a Screening Tool for Subclinical Atherosclerosis

Aim: We evaluated the validity of circumferential carotid artery strain as a marker for subclinical atherosclerosis and its benefit in addition to carotid intima-media thickness (IMT) to detect high-risk groups. Methods: The study was a cross-sectional study. From April 2007 to July 2008, 1057 patients who had undergone both echocardiography and carotid ultrasonography were consecutively enrolled. Circumferential carotid strain was obtained from the ratio of change in circular length during the cardiac cycle. Results: As the number of risk factors for atherosclerosis increased from 0 to >= 4, circumferential strain decreased accordingly (5.1 +/- 2.1, 4.4 +/- 1.8, 3.8 +/- 1.6, 3.3 +/- 1.3, 3.1 +/- 1.3%, p < 0.001), whereas carotid IMT and beta-stiffness increased (p < 0.001 for both IMT and beta-stiffness). Patients with a high Framingham risk score (FRS) also showed lower circumferential strain (5.01 +/- 2.19, 3.46 +/- 1.34, 3.08 +/- 1.38, p < 0.001 for FRS <5%, 5-15% and >15%). Compared to patients with documented atherosclerotic disease, patients without known atherosclerotic disease showed significantly higher circumferential strain (3.25 +/- 1.30 vs. 4.18 +/- 1.89%, p < 0.001 for patients with vs. without documented atherosclerotic disease). The addition of circumferential carotid strain to IMT significantly improved the ability to detect patients at high risk for coronary heart disease, as assessed by the Framingham risk score (chi(2) = 61.0 from 42.4, p < 0.001), whereas beta-stiffness did not have additive power (p = 0.439). Conclusion: Circumferential strain can be used as a screening tool for subclinical atherosclerosis and may help detect subjects at increased risk for atherosclerotic disease.