Autonomic function and cardiorespiratory coupling analysis in patients with chronic heart failure with reduced and preserved ejection fractions

Chronic heart failure (CHF) is a syndrome in which the heart fails to pump enough blood to meet the body’s needs. It is classified into two phenotypes: CHF with preserved ejection fraction (HFpEF) and reduced ejection fraction (HFrEF). CHF disrupts autonomic control and cardiorespiratory coupling (CRC). CRC quantifies the dynamic interactions between heart period (HP) and respiration (RESP). The assessment of CRC offers insights beyond traditional univariate markers, such as the high frequency (HF, 0.15-0.5 Hz) power of HP variability (HFaHP) and the power of variability of the time interval between Q-wave onset and T-wave end (QT) in the low frequency (LF) band (LFaQT). In this study, we analyzed HFaHP, LFaQT, and CRC strength in 29 subjects belonging to three gender-balanced groups (HFrEF: n=10, 62±11 yrs; HFpEF: n=9, 56±14 yrs; CTRL: n=10, 58±9 yrs). CRC was estimated via K2 between RESP on HP at the respiratory rate. Compared to HFrEF in the HFpEF group, K2 and HFaHP were reduced (0.80±0.16 vs 0.46±0.22 and 158±80 ms2 vs 113±94 ms2 respectively) and LFaQT was increased (48±55 ms2 vs 143±109 ms2). Markers in CRTL group were more similar to HFrEF. These results suggest compensatory autonomic mechanisms that help maintain proper cardiac function, with these responses depending on the CHF phenotype.