Pulse wave transit time during exercise testing reflects the severity of heart disease in cardiac patients

The pulse wave transit time (PWTT) is easily measured as the time from the R wave of an electrocardiogram to the arrival of the pulse wave measured by an oxygen saturation monitor at the earlobe. We investigated whether the change of PWTT during exercise testing reflects cardiopulmonary function. Eighty-nine cardiac patients who underwent cardiopulmonary exercise testing (CPX) were enrolled. We analyzed the change of PWTT during exercise and the relationship between the shortening of the PWTT and CPX parameters. PWTT was significantly shortened from rest to peak exercise (204.6 ± 33.6 vs. 145.6 ± 26.4 msec, p < 0.001) in all of the subjects. The patients with heart failure had significantly higher PWTT at peak exercise than the patients without heart failure (152.7 ± 27.1 vs. 140.4 ± 24.8 msec, p = 0.031). The shortening of PWTT from rest to peak exercise showed significant positive correlations with the peak O₂ uptake (VO₂) (r = 0.56, p < 0.001), anaerobic threshold (r = 0.40, p = 0.016), and % increase of systolic blood pressure during exercise (r = 0.75, p < 0.001), and a negative correlation with the slope of the increase in ventilation versus the increase in CO₂ output (VE-VCO₂ slope) (r = - 0.42, p = 0.010) in the patients with heart failure. PWTT was shortened during exercise as the exercise intensity increased. In the patients with heart failure, the shortening of PWTT from rest to peak exercise was smaller in those with lower exercise capacity and those with higher VE-VCO₂ slope, an established index known to reflect the severity of heart failure.