Ambulatory low cardiac output state in heart failure: characteristics and outcomes

Ambulatory low cardiac output state (LCOS) is a known but poorly described heart failure (HF) phenotype. We aimed to investigate the prevalence, clinical markers, and prognostic importance of ambulatory LCOS.

Consecutive ambulatory patients with HF and reduced left ventricular ejection fraction referred for advanced HF assessment were included. All patients underwent right heart catheterization. Patients with LCOS defined as a cardiac index <1.8 L/min/m2 were compared to patients without LCOS.

In total, 618 patients were included. The mean ± SD age was 52.5 ± 12.5 years, and 78% were male. Low cardiac output state was present in 116 patients (19% [95% CI 16 to 22%]). Patients with LCOS presented with more advanced symptoms, lower systolic blood pressure and LVEF, higher N-terminal pro-B-type natriuretic peptide levels, and were less likely to receive treatment with renin-angiotensin system inhibitors (RASi) compared with patients without LCOS. Absence of RASi therapy was strongly associated with LCOS, odds ratio 2.34 [95% CI 1.44 to 3.74], P < .001. While liver function markers were more elevated in patients with LCOS, renal function was similar between groups. Over a median follow-up of five years, LCOS was independently associated with mortality, hazard ratio 1.86 [95% 1.32 to 2.62], P < .001 (adjusted for age, sex, and advanced therapy).

LCOS was observed in 19% of ambulatory patients and was strongly associated with mortality, independent of left-sided filling pressures and advanced therapies. Among other factors, the absence of RASi therapy was highly predictive of LCOS.