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 (Delta PWV) between systolic and diastolic (cPWV(d)) carotid pulse wave velocity. Biomechanically, a greater Delta PWV implies greater increases in left ventricular afterload with physical activity. Therefore, we hypothesized, that Delta PWV 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), Delta PWV was obtained from combined carotid artery ultrasound and tonometry recordings. Multiple linear regression analysis was performed to investigate the associations of Delta PWV, cPWV(d) and aPWV with LVMI, adjusting for age, sex, mean blood pressure (MBP), central pulse pressure, and other possible confounders. Results: DPWV 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. Delta PWV was significantly associated with LVMI (beta of 2.46 g/m(1.7) per m/s, P <0.001), even after full adjustment (beta 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 (beta 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.