Adaptive-Lag approach for assessing baroreflex functions: validation with the eurobavar dataset

The arterial baroreflex is a fundamental short-term feedback mechanism stabilizing arterial pressure through autonomic modulation of heart rate and vascular tone. Conventional sequence method for Baroreflex sensitivity (BRS) assessment assumes a fixed delay between systolic pressure and cardiac interval responses, overlooking the physiological variability in reflex latency that arises from differences in neural conduction and effector kinetics. We developed and validated an Adaptive Lag (AL) Baroreflex Sensitivity method that accommodates variable delays, thereby quantifying both reflex gain and lag in response. Using 42 recordings from the EuroBaVar dataset, we compared the AL-BRS method (incorporating variable lags of 0-10 beats), to conventional sequence and spectral methods. The AL approach identified 34% more baroreflex sequences and demonstrated excellent agreement (r = 0.99) with fixed lag BRS. Also, Baroreflex Response Lag (BRL) was also determined which was significantly longer in subjects with impaired baroreflex function (supine: 2.35 vs. 1.16 beats). AL-BRS and BRL, showed superior diagnostic performance for identifying baroreflex impairment (AUC = 0.86 and 0.87, respectively), with BRL being excellent during standing (AUC = 0.95). These findings demonstrate that incorporating variable response time into BRS assessment not only refines sensitivity estimation but also reveals BRL as a temporal feature of baroreflex control, which carries diagnostic and potentially prognostic value in autonomic regulation. Thus AL-BRS method provides a more physiologically complete assessment of baroreflex function. This work advances the field by offering a refined, publicly available tool (implemented in MATLAB and R) for research and clinical applications.