The change in arterial stiffness over the cardiac cycle rather than diastolic stiffness is independently associated with left ventricular mass index in healthy middle-aged individuals
Background: The current standard for arterial stiffness assessment, aortic pulse wave velocity (aPWV), is measured at diastolic pressure. Arterial stiffness, however, is pressure dependent. At the carotid artery level, the degree of this dependency can be quantified as the difference (ΔPWV) between systolic and diastolic (cPWV d ) carotid pulse wave velocity. Biomechanically, a greater ΔPWV implies greater increases in left ventricular afterload with physical activity. Therefore, we hypothesized, that ΔPWV is more strongly associated with left ventricular mass index (LVMI) than aPWV and cPWV d . Methods: In 1776 healthy individuals from the Asklepios cohort (age 35-55 years), ΔPWV was obtained from combined carotid artery ultrasound and tonometry recordings. Multiple linear regression analysis was performed to investigate the associations of ΔPWV, cPWVd and aPWV with LVMI, adjusting for age, sex, mean blood pressure (MBP), central pulse pressure, and other possible confounders. Results: ΔPWV was 2.4 ± 1.2 m/s (mean ± SD), ranging from 0.8 m/s, indicating almost constant arterial stiffness over the cardiac cycle, to 4.4 m/s, reflecting substantial pressure dependency. ΔPWV was significantly associated with LVMI (β of 2.46 g/m 1.7 per m/s, P < 0.001), even after full adjustment (β of 0.56 g/m 1.7 per m/s, P=0.03). cPWV d and aPWV had clear crude associations with LVMI (P < 0.001), but lost significance after adjustment (β of-0.48 and-0.33 g/m 1.7 per m/s, with P=0.11 and 0.2, respectively). Conclusion: The change in arterial stiffness over the cardiac cycle, rather than diastolic stiffness, is independently associated with LVMI in healthy middle-aged individuals. Therefore, the pressure dependency of arterial stiffness should be considered in cardiovascular risk assessment.