Serum Chloride and the Response to Acetazolamide in Patients With Acute Heart Failure and Volume Overload: A Post Hoc Analysis From the ADVOR Trial

BACKGROUND: Chloride plays a crucial role in renal salt sensing. This study investigates whether serum chloride is associated with clinical outcomes and decongestive response to acetazolamide in patients with acute decompensated heart failure. METHODS: This post hoc analysis includes all 519 patients from the ADVOR trial (Acetazolamide in Decompensated Heart Failure With Volume Overload), randomized to intravenous acetazolamide or matching placebo on top of intravenous loop diuretics. The impact of baseline serum chloride on the main trial end points and the treatment effect of acetazolamide was assessed, as was the evolution of serum chloride under decongestive treatment. RESULTS: Hypochloremia (<96 mmol/L) and hyperchloremia (>106 mmol/L) were present in 80 (15%) and 53 (10%), respectively, at baseline. Hypochloremia was associated with significantly slower decongestion, a longer length of hospital stay, and increased risk of all-cause mortality and heart failure readmissions. Acetazolamide increased the odds of successful decongestion and reduced length of stay irrespectively of baseline serum chloride levels. No statistically significant interaction between serum chloride levels and the effect of acetazolamide on death or heart failure readmissions was observed. The placebo group exhibited a progressive decline in serum chloride, which was effectively prevented by acetazolamide (P<0.001). CONCLUSIONS: Hypochloremia is associated with diuretic resistance and worse clinical outcomes. Add-on acetazolamide therapy improves decongestion across the entire range of serum chloride and prevents the drop in chloride levels caused by loop diuretic monotherapy.