Prognostic significance of plasma chloride in elderly patients hospitalized for acute heart failure

AIMS: Previous studies demonstrated the relationship between hypochloraemia and poor prognosis in patients hospitalized for acute heart failure (AHF). However, the usefulness of chloride in clinical practice remains uncertain, notably in very old patients with predominantly heart failure (HF) with preserved ejection fraction (HFpEF). We aimed to evaluate the prognostic impact of chloride in a cohort of very aged patients with AHF and the possible existence of different phenotypes of hypochloraemia with distinct clinical significance. METHODS AND RESULTS: It was an observational study of 429 patients hospitalized for AHF in which chloraemia was measured. Two different phenotypes of hypochloraemia were identified by their relationship with estimated plasma volume status (ePVS) as a proxy of intravascular congestion. The endpoint of interest was time to all‐cause mortality and the composite of death and/or HF readmission. A multivariable Cox proportional hazard regression model was constructed to analyse the endpoints. The median age was 85 (78–92) years, 266 (62%) were women, and 80% had HFpEF. After multivariable analysis, chloraemia, but not natraemia, was associated with the risk of death and HF readmission in a U‐shaped pattern. The phenotype characterized by hypochloraemia and low ePVS (depletional) was associated with an increased risk of mortality when compared with patients with normochloraemia [hazard ratio (HR) 1.86, P = 0.008]. In contrast, hypochloraemia with high ePVS (dilutional) had no prognostic significance (HR 0.94, P = 0.855). CONCLUSIONS: In very old patients hospitalized with AHF, plasma chloride was associated with the risk of death and HF readmission in a U‐shaped pattern and could potentially be used for congestion phenotyping.