Comparison of non-invasive estimation of central aortic blood pressure and biomarkers of vascular health measured by two devices using brachial cuff waveforms

Introduction: The pulse wave analysis technology in the specialist SphygmoCor XCEL device has now been implemented in the CONNEQT Pulse device, which is a conventional sphygmomanometer suitable for home blood pressure (BP) monitoring. The aim of this study was to compare the correlation and consistency of measurements between the two devices. Methods: The study was conducted in participants admitted to the Department of Geriatrics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine. Brachial BP (bBP), central BP (cBP), augmentation pressure (AP), augmentation index (AIx), and subendocardial viability ratio (SEVR) were measured with the CONNEQT Pulse and the SphygmoCor XCEL devices, both using a calibrated cuff-based brachial waveform. Results: A total of 367 eligible subjects, aged 23-92 (57.6 ± 13.0) years, of whom 254 (69.2%) were male, was enrolled in this study. Paired t tests showed relatively low bias and elevated standard deviation: cSBP mm Hg ([121.7± 17.2] vs. [117.5± 14.5], p < 0.001), cDBP ([80.6± 11.0] vs. [78.3± 11.4], p < 0.001), cPP ([41.0± 12.7] vs. [39.2± 9.5], p < 0.001), AP mm Hg ([11.5± 6.2] vs. [12.8± 6.6], p < 0.001), AI ([26.4 ± 9.0]% vs. [31.9± 14.0]%, p < 0.01), and SEVR ([135.6± 25.5]% vs. [137.8 ± 26.4]%, p = 0.02). cDBP (r = 0.812) measured by both devices was strongly correlated, cSBP (r = 0.762), cPP (r = 0.702) and SEVR (r = 0.778) were strongly correlated, whereas AP (r = 0.587) and AIx (r = 0.522) were moderately correlated (all p < 0.001). For intraclass correlation coefficient (ICC) for both devices, cDBP (ICC = 0.794) and SEVR (ICC = 0.776) showed good reproducibility, while cSBP (ICC = 0.727), cPP (ICC = 0.666), AIx (ICC = 0.428), and AP (ICC = 0.575) showed good to modest reproducibility. The differences between cSBP, cDBP, cPP, AP, AIx, and SEVR measured by the two devices were 4.2 ± 11.2 mm Hg, 2.3 ± 6.9 mm Hg, -1.8 ± 9.0 mm Hg, -1.3 ± 5.8 mm Hg, -5.6 ± 12.0%, and 2.1 ± 17.3%, respectively. Conclusion: Both devices show strong cBP-bBP correlations and low bias, suggesting that the new CONNEQT Pulse provides similar measurements of cBP to the original SphygmoCor XCEL. Although there is greater variability in waveform parameters, the magnitude of differences is within acceptable limits for meaningful use in conventional home BP monitoring. The relatively elevated variability in measurement precision (standard deviation), most likely due to sequential measurements with both devices in the same arm, needs to be further evaluated using simultaneous measurements in both arms.