Trajectory of serum chloride levels during decongestive therapy in acute heart failure

Background: Hypochloremia is a risk factor for poor outcomes in patients with acute heart failure (AHF). However, the changes in serum chloride levels during decongestion therapy and their impact on prognosis remain unknown. Methods: In total, 2798 patients with AHF were retrospectively studied and divided into four groups according to their admission and discharge serum chloride levels: (1) normochloremia (n=2,192, 78%); (2) treatment-associated hypochloremia, defined as admission normochloremia with a subsequent decrease (<98 mEq/L) during hospitalization (n=335, 12%); (3) resolved hypochloremia, defined as admission hypochloremia that disappeared at discharge (n=128, 5%); (4) persistent hypochloremia, defined as chloride <98 mEq/L at admission and discharge (n = 143, 5%). The primary outcome was all-cause death, and the secondary outcomes were cardiovascular death and a composite of cardiovascular death and rehospitalization for heart failure after discharge. Results: The mean age was 76 ± 12 years and 1584 (57%) patients were men. The mean left ventricular ejection fraction was 46 ± 16%. During a median follow-up period of 365 days, persistent hypochloremia was associated with an increased risk of all-cause death (adjusted hazard ratio [95% confidence interval]: 2.27 [1.53–3.37], p < 0.001), cardiovascular death (2.38 [1.46–3.87], p < 0.001), and a composite of cardiovascular death and heart failure rehospitalization (1.47 [1.06–2.06], p = 0.022). However, the outcomes were comparable between patients with resolved hypochloremia and normochloremia. Conclusions: Persistent hypochloremia was associated with worse clinical outcomes, while resolved hypochloremia and normochloremia showed a comparable prognosis. Changes in serum chloride levels can help identify patients with poor prognoses and can be used to determine subsequent treatment strategies.