Oral acetazolamide in acute heart failure: effects on renal function and clinical outcomes

Background Congestion remains the primary cause of hospitalisation in acute heart failure. Although furosemide is the mainstay diuretic, its efficacy is limited. The ADVOR trial demonstrated the effectiveness of intravenous acetazolamide, but its availability is restricted in many regions. As a result, oral acetazolamide is empirically used, yet its effects remain unclear. This study aims to evaluate the safety and clinical outcomes of oral acetazolamide in acute heart failure. Purpose To evaluate the impact of oral acetazolamide on diuresis, weight change, renal function, electrolyte balance, in-hospital mortality, length of stay, and rehospitalisation rates in patients with acute heart failure receiving conventional diuretic therapy. Methods A retrospective cohort study was conducted using electronic medical records. Clinical and laboratory data were collected and analysed. Continuous variables were assessed for normality using the Shapiro-Wilk test. Comparisons were performed using paired t-tests or Wilcoxon signed-rank tests for continuous variables and chi-square or Fisher’s exact tests for categorical variables. A p-value <0.05 was considered statistically significant. Results A total of 85 patients were included (mean age: 62 years ± 15, 39% female). Over half had a left ventricular ejection fraction <40%, and 66% were managed in intensive care units. The median intravenous furosemide dose at acetazolamide initiation was 160 mg (IQR 80–160). No significant differences were found in diuresis or weight change after acetazolamide use. However, acetazolamide was associated with an increase in serum creatinine (1.36 vs 1.56, p=0.00017) and a decrease in estimated glomerular filtration rate (52 vs 42, p=0.000025). A mild increase in bicarbonate levels was observed (28.2 vs 27.2, p=0.022). In-hospital mortality was 13%, and the 3-month rehospitalisation rate was 32%. Beta-blocker and SGLT2 inhibitor use were associated with lower in-hospital mortality and shorter length of stay. Conclusion(s) In this high-risk acute heart failure cohort, oral acetazolamide was associated with a decline in renal function without significant changes in diuresis or weight. The study’s retrospective nature, high-risk population, heterogeneous treatment protocols, and lack of a control group limit generalizability. Caution is advised when using oral acetazolamide, and further prospective trials are needed to confirm its safety and efficacy.Comparison of creatinine and eGFR before Cohort characteristics