Ambulatory Low Cardiac Output State in Heart Failure: Characteristics and Outcomes.

INTRODUCTION: 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. METHODS: 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. RESULTS: In total, 618 patients were included. Mean ± SD age was 52.5 ± 12.5 years, and 78 % were male. LCOS 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 < 0.001. 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 < 0.001 (adjusted for age, sex, and advanced therapy). CONCLUSION: 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.