Admission hypochloremia and early chloride trajectories as markers of difficult decongestion in acute heart failure

Abstract Background Hypochloremia is common in acute heart failure, but it remains uncertain whether early in-hospital chloride trajectories provide clinically relevant information beyond chloride status at admission. Among patients with paired admission and 48–72-hour chloride measurements, we evaluated the association of admission hypochloremia with decongestion-related outcomes and examined whether early chloride trajectories provided additional information. Methods This retrospective cohort included 301 adults hospitalized with acute heart failure. Admission hypochloremia was defined as serum chloride < 98 mmol/L and was compared with admission normochloremia (≥ 98 mmol/L). Separate multivariable logistic regression models examined physician-documented diuretic resistance and residual congestion at discharge as the principal decongestion outcomes; worsening renal function and 90-day heart failure readmission were evaluated as secondary outcomes. The readmission analysis was restricted to patients discharged alive. Four chloride-trajectory categories were subsequently evaluated as exploratory exposures, and model fit was compared using the Akaike information criterion and likelihood-ratio tests. Results Admission hypochloremia was present in 102 patients (33.9%). After adjustment for age, sex, body mass index, heart failure phenotype, admission estimated glomerular filtration rate, albumin, log-transformed N-terminal pro-B-type natriuretic peptide, and right ventricular dysfunction, admission hypochloremia was associated with the principal decongestion outcomes of physician-documented diuretic resistance (adjusted odds ratio [OR], 2.68; 95% confidence interval [CI], 1.51–4.77; p < 0.001) and residual congestion (adjusted OR, 2.79; 95% CI, 1.52–5.13; p = 0.001). A less robust secondary association was observed with worsening renal function (adjusted OR, 1.86; 95% CI, 1.01–3.42; p = 0.046). The analysis did not demonstrate a clear association between admission hypochloremia and 90-day heart failure readmission among 292 patients discharged alive (adjusted OR, 1.37; 95% CI, 0.68–2.76; p = 0.385). Four-category trajectory models did not demonstrate statistically significant incremental fit over admission-status models for any outcome. Conclusions Among patients who underwent paired chloride measurement, admission hypochloremia was associated with physician-documented diuretic resistance and residual congestion. The association with worsening renal function was a less robust secondary finding. Early chloride trajectories did not significantly improve model fit beyond admission chloride status.