Abstract TP99: Non-invasive Aortic Pulse Wave Velocity is Related to Gold Standard Carotid-femoral Pulse Wave Velocity: Implications for Monitoring Large Artery Stiffness in the Clinic

Introduction: Aortic stiffness is an independent predictor of fatal stroke in both hypertensive populations and healthy subjects, but traditional monitoring methods have had difficulty being incorporated into routine practice. The gold standard, carotid-femoral pulse wave velocity (cfPWV), poses methodological challenges as this method bypasses the most distensible vessel, the proximal aorta. We propose a new method, aortic arch pulse wave velocity (aaPWV) assessed via ultrasound, which encompasses the proximal aorta and can be performed during standard cardiac echocardiography. We sought to determine if the two methods were related. Methods: We recruited 44 healthy volunteers (38.1y [SEM: 2.39], range 20-62y, 80% female) for this study. Both aaPWV and cfPWV were measured by the wave-foot method using a commercial Logic S8 Ultrasound system (GE Healthcare) with synchronous electrocardiogram. cfPWV was calculated by determining the time delay between the two vessels and dividing by the measured distance between the two sites. aaPWV was calculated by determining the time delay between onset of aortic ejection from the apical 5-chamber view and the arrival of the pulse wave at the start of descending aorta in the suprasternal view. Distance for aaPWV was estimated using regression equation from the literature. Results: Paired t-tests revealed cfPWV was significantly greater than aaPWV (5.98 ± 0.17m/s vs. 4.7 ± 0.29m/s; P<0.001). Pearson correlation revealed the two methods were related (r=0.35, P=0.01) and intraclass correlation coefficient revealed good agreement within and between raters (0.75, 0.85 respectively; 0.75-0.9 indicate good agreement). Conclusion: We report that while aaPWV and cfPWV are correlated, significant differences exist, which was expected given the proximal segment is the most elastic portion of the aorta. The findings from this study suggest aaPWV could be a more feasible method to measure large artery stiffness in routinely in the clinic, but future studies are needed to determine if aaPWV is similarly predictive of adverse cardiovascular outcomes.