Net synergy/redundancy balance of cardiovascular interactions allows the stratification of the risk in patients with asymptomatic carotid stenosis

The net balance between redundancy and synergy can be exploited to characterize cardiovascular control from spontaneous variability of systolic arterial pressure (SAP) and heart period (HP) in patients with asymptomatic carotid stenosis (ACS), whose impairment could be graded according to features of the carotid plaque. A predictive information decomposition approach based on bivariate autoregressive model of HP with an exogenous SAP input was applied in 67 patients with ACS scheduled for carotid endarterectomy (age 74.9±7.6 yrs, 44 males). Patients were divided in two groups according to the presence of a plaque fibrous cap thicker than 200 µm (CAP>200, n=40) or not (CAP<200, n=27) as detected from postoperative histological analysis. HP and SAP time series were acquired preoperatively in supine position and during active standing (STAND). Redundancy was prevalent over synergy in both populations and conditions. During STAND, a more negative net synergy\redundancy balance, indicating a more prevalent redundancy, was observed in CAP>200. Findings suggest that in patients with thicker fibrous cap the shared contribution of baroreflex and non-baroreflex regulatory mechanisms to cardiac control is more important, thus indicating a greater fault tolerance. Advanced information domain markers can thus be exploited for risk stratification in ACS patients.