Whole-Body Impedance Cardiography-Derived Haemodynamic Parameters Associated With Outcomes in Clinically Stable Heart...

Heart failure with reduced ejection fraction (HFrEF) is one of the most prevalent chronic cardiac conditions. Despite recent advances, overall morbidity and mortality remain high. Routine outpatient evaluation is predominantly based on subjective descriptions of symptoms. The utility of non-invasively obtained haemodynamic parameters in identifying high-risk patients with HFrEF has not been described.

Clinically stable (>3 months) patients with HFrEF from the tertiary HF clinic at St. Boniface Hospital, Canada were recruited. Resting and exercise-augmented (25 watts, up to 12 minutes on a mounted bike) haemodynamic parameters were obtained using a Non-Invasive Cardiac System (NICaS), a whole-body impedance cardiography-based technology. Electronic patient records were reviewed to identify outcomes.

Overall, 63 patients (63.4±15.4 years; 11 [17.5%] female, mean body mass index 31.0±7.1 kg/m²) were recruited. Resting stroke index (SI) correlated with post-exercise SI (r=0.56). At 12-month follow-up, 25 of 63 subjects (39.7%) experienced adverse outcomes (emergency department presentation or unplanned HF hospitalisation, new-onset arrhythmia, referral for cardiac implantable electronic device implantation/optimisation, referral for palliative care and all-cause death). Lower resting SI, either supine (35.5±9.5 vs 40.3±8.0 mL/m²; p=0.02) or sitting (32.1±7.9 vs 37.6±7.9 mL/m²; p=0.009) and exaggerated exercise-augmented Granov-Goor index, a surrogate marker of impaired left ventricular contractility, were the hemodynamic parameters most strongly associated with outcomes.

Non-invasively obtained resting SI and higher exercise-augmented Granov-Goor index identify a high-risk cohort among patients with clinically stable HFrEF. Such findings should be validated in a larger prospective study.