Sympathetic Score in Heart Failure: an ECG data-driven proposal

Heart Failure (HF) is a clinical syndrome whose signs and symptoms gradually become incapacitating for the patient. Representing almost half of the HF incidence worldwide, Heart Failure with preserved Ejection Fraction (HFpEF) remains in constant growth, being associated with an increase in costs and the need for resources. Cardiac Rehabilitation Programs (CRPs), as a secondary prevention strategy, are multidisciplinary structured interventions that include the prescription of physical exercise, healthy habits, and nutritional counseling. The Physiopathology of HF includes the overactivation of the sympathetic nervous system, and access to this increased activity in the context of cardiovascular rehabilitation constitutes valuable information for exercise prescription. Accordingly, the main goal of this work is to propose a score of sympathetic activation in HFpEF patients, to be applied in the context of CRPs for exercise prescription. The methodology here proposed is based on a long-term Electrocardiogram (ECG) acquisition, followed by the extraction of autonomic attributes to conduct a Principal Component Analysis approach yielding a score of autonomic activation. Three cases were tested by using distinct sets of attributes, highlighting the contribution of using all attributes versus applying only the ones related to the specific part of the autonomic function, as is the case when the very low-frequency band is included to derive the activation score for the sympathetic system. The proposed methodology is a simple and easy-to-use method to compare, within a group with similar initial characteristics, the extent to which the intervention is changing the initial status of each individual when compared withing one group with similar phenotype.