Wave Reflection Measured by Peripheral Arterial Tonometry is Related to Cardiovascular Risk Factors in Adults: The ELSA-Brasil Cohort Study

Introduction: Augmentation index (AIx) measures the contribution that wave reflection makes to arterial pressure. Higher values of AIx measured by arterial tonometry associate with risk factors and predict cardiovascular events. Recently, peripheral arterial tonometry (PAT) waveforms have been used to calculate PAT-AIx. We evaluated the clinical correlates of PAT-AIx and its relation to carotid-femoral pulse wave velocity (PWV), a measurement of arterial stiffness. Methods: In a cross-sectional study, 1535 participants of ELSA-Brasil, a multi-site, Brazilian cohort study underwent PAT. PAT-AIx is calculated by averaging the baseline pulse amplitude data and using the formula: PAT-AIx=(P2 – P1)х100/P1(%). To investigate the association of PAT-AIx and cardiovascular risk factors, linear regression was used for multivariable analyses. Partial correlation coefficients adjusted for age, sex, heart rate, height, and multivariable-adjusted for cardiovascular risk factors were used to study the relation of PAT-AIx and PWV. P≤0.05 were considered statistically significant. Results: Participants’ mean age was 52±9 years, 44% were women and 49% nonwhite. PAT-AIx values were 7.3±15.8% for men and 16.7±16.6% for women. Multivariable analysis revealed that PAT-AIx was higher in women, and with advancing age, smoking, and higher mean systolic and diastolic pressures. PAT-AIx was inversely correlated to higher mean heart rate, height, BMI and prevalent cardiovascular disease. There was no association of PAT-AIx with diabetes or dyslipidemia. There was a significant age and sex interaction: the beta coefficient for men was 0.61 (CI95% 0.51-0.72) and for women 0.39 (CI95% 0.25-0.52). In women, PAT-AIx values tended to plateau at age of 55 years, getting closer to men’s values. PAT-AIx correlated with PWV in both models (r=0.13, p Conclusions: PAT-AIx, a novel measure of peripheral wave reflection, is associated with cardiovascular risk factors consistent with studies that used arterial tonometry. The age and sex interaction shows that the increase in PAT-AIx with advancing age is greater in men than women. The modest correlation of PAT-AIx and PWV suggests that PAT-AIx has complex determinants, including aortic stiffness.