Forward and Backward Wave Morphology and Central Pressure Augmentation in Men and Women in the Framingham Heart Study

Central pressure augmentation is associated with greater backward wave amplitude and shorter transit time and is higher in women for reasons only partially elucidated. Augmentation also is affected by left ventricular function and shapes of the forward and backward waves. The goal of this study was to examine the relative contributions of forward and backward wave morphology to central pressure augmentation in men and women. From noninvasive measurements of central pressure and flow in 7437 participants (4036 women) aged from 19 to 90 years (mean age, 51 years), we calculated several variables: augmentation index, backward wave arrival time, reflection factor, forward wave amplitude, forward wave peak width, and slope of the backward wave upstroke. Linear regression models for augmentation index, adjusted for height and heart rate, demonstrated nonlinear relations with age (age: B=4.6±0.1%; P<0.001; age2: B=−4.2±0.1%; P<0.001) and higher augmentation in women (B=4.5±0.4%; P<0.001; model R2=0.35). Addition of reflection factor and backward wave arrival time improved model fit (R2=0.62) and reduced the age coefficients: age (B=2.3±0.1%; P<0.001) and age2 (B=−2.2±0.1%; P<0.001). Addition of width of forward wave peak, slope of backward wave upstroke, and forward wave amplitude further improved model fit (R2=0.75) and attenuated the sex coefficient (B=1.9±0.2%; P<0.001). Thus, shape and amplitude of the forward wave may be important correlates of augmentation index, and part of the sex difference in augmentation index may be explained by forward and backward wave morphology.