Intermachine Variability Between the Sphygmocor CVMS and Sphygmocor Xcel Device in Young Healthy Adults: A Pilot Study

Abstract

Objective: Carotid-femoral pulse wave velocity (cf-PWV) is considered the gold-standard measure for arterial stiffness. The SphygmoCor CVMS uses applanation tonometry on the carotid and femoral arteries, synchronized with an ECG signal. The more recent SphygmoCor XCEL eliminates the need for ECG gating by utilizing leg cuff detection of the femoral pulse in conjunction with carotid tonometry. The latter method is more time-efficient, but may yield different cf-PWV values. The aim of this pilot study is to validate the use of the SphygmoCor XCEL against the SphygmoCor CVMS. Design and method: Measurements of the right carotid and femoral artery were conducted using the SphygmoCor CVMS (AtCor Medical), immediately followed by the SphygmoCor XCEL (AtCor Medical). These measurements were performed under standardized conditions, namely in a fasted state and after 15 minutes of rest in a supine position in a quiet room (20̊). All measurements were done in triplicate and were repeated when they did not meet the quality control guidelines, as defined by the manufacturer. The mean difference and SD of the difference between the two devices was calculated and visualized through scatter plot and Bland-Altman analysis. Correlation coefficient as well as intraclass correlation (ICC) was calculated. Results: A total of nine (5 females) non-smoking, physically active individuals were included, with a MEDIAN age of 21 years (21-36) and MEDIAN BMI of 21.8 (18,4-25,8). Mean cf-PWV measured by SphygmoCor CVMS was 8.11 ± 0.69 m/s and by SphygmoCor XCEL was 7.61 ± 0.16 m/s. Measurements by both techniques were significantly correlated (R = 0,75; P<0,05; Fig1). The mean difference between the two measurement techniques was 0.50 ± 0.81 m/s, which is ‘acceptable’ according to the ARTERY Society guidelines. Bland-Altman analysis revealed limits of agreement ranging from -1.09 to 2.09 m/s. A ‘moderate’ agreement was documented (ICC = 0.51). Conclusions: In this pilot study, the SphygmoCor XCEL demonstrated acceptable agreement with the SphygmoCor CVMS. Bland-Altman plots show that with higher cf-PWV values, there could be a tendency towards overestimation of the cf-PWV by the SphygmoCor EXCEL. Further validation is needed in larger cohorts and other populations.