Background:
Arterial stiffness is a well-recognized predictor of cardiovascular disease (CVD). ECG R-wave to Radial artery pulse delay (RRD) is a novel hemodynamic index in which arterial stiffness is an important component (shorter delay = Higher arterial stiffness) and is obtainable from a single tonometric measurement at the radial artery with simultaneous ECG. Sleep disordered breathing (SDB) has emerged as a risk factor for CVD. The aim of the study was to determine the association of SDB with RRD.
Methods:
Multi-Ethnic Study of Atherosclerosis participants in 2010-2012 without overt CVD who underwent a sleep study, radial artery tonometry and cardiac MRI were eligible for this cross-sectional analysis (N = 1173, Mean [SD] age: 67.8 ± 8.8, Women: 55.4%). Independent associations between SDB indices including apnea hypopnea index (AHI) and oxygen (O2) desaturation index (ODI: events with more than 4% O2 desaturation), and RRD (transit time in msec) were examined. Model was constructed to adjust for isovolumetric contraction time, another component of RRD, by including measures of contractility and preload (left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDV) respectively).
Results:
Median [IQR] of AHI and ODI were 7.9/hr [2.9- 18.0] and 7.5/hr [3.0- 17.5] respectively. Adjusting for transit path length, demographic factors, BMI and CVD risk factors, both AHI and ODI were inversely associated with RRD (β= -50.3 msec per SD, p = 0.09 and β= -0.60.2 msec per SD, p = 0.04 respectively). In gender stratified analyses given presence of significant interaction, measures of SDB were predictive of RRD only in men. No significant associations were found with key nocturnal hypoxemia indices including mean O2 saturation (SpO2), percent time with SpO2less than 90 % and minimum SpO2. Men, older age, Asian race, high blood pressure, LVEF and LVEDV were also inversely associated with RRD.
Conclusion:
SDB was associated with shorter RRD implying higher arterial stiffness in men only. These findings suggest the importance of apnea related dynamic change in SpO2 (intermittent hypoxia and reoxygenation) in its potential link to arterial stiffness and also highlights effect modification by gender in the association between the two.
POS-758 IMPACT OF REDUCTION OF ARTERIAL STIFFNESS AFTER KIDNEY TRANSPLANT ON RADIAL ARTERY SYSTOLIC-DIASTOLIC PEAK-TO-PEAK TRANSIT TIME