Similarities and Distinctions Between Acetazolamide and Sodium–Glucose Cotransporter 2 Inhibitors in Patients with Acute Heart Failure: Key Insights Into ADVOR and EMPULSE

Both acetazolamide and sodium-glucose cotransporter 2 (SGLT2) inhibitors block sodium reabsorption in the proximal renal tubule primarily through inhibition of sodium-hydrogen exchanger isoform 3 (NHE3), but neither SGLT2 inhibitors nor acetazolamide produce a sustained natriuresis due to compensatory upregulation of sodium reabsorption at distal nephron sites. Nevertheless, acetazolamide and SGLT2 inhibitors have been used as adjunctive therapy to loop diuretics in states where NHE3 is upregulated, e.g. acute heart failure. Two randomized controlled trials have been carried out with acetazolamide in acute heart failure (DIURESIS-CHF and ADVOR). In ADVOR, acetazolamide improved physical signs of fluid retention, but this finding could not be explained by the modest observed diuretic effect. Acetazolamide did not produce a natriuresis in the DIURESIS-CHF trial, and in ADVOR, immediate effects on symptoms and body weight were not reported, and the drug had no effect on morbidity or mortality after 90 days. Three randomized controlled trials have been carried out with empagliflozin (EMPAG-HF, EMPA-RESPONSE-AHF and EMPULSE) in acute heart failure. The EMPULSE trial did not report effects on diuresis or in changes in physical signs of congestion during the first week of treatment, but in EMPAG-HF and EMPA-RESPONSE-AHF, empagliflozin had no effect of dyspnoea, urinary sodium excretion or body weight during the first 4 days. In the EMPULSE trial, empagliflozin improved health status at 15 days and reduced the risk of worsening heart failure events at 90 days, but these effects are similar in magnitude and time course to the early statistical significance on the risk of heart failure hospitalizations achieved within 14-30 days in the major trials of SGLT2 inhibitors in patients with chronic heart failure. Neurohormonal inhibitors produce this early effect in the absence of a diuresis. Additionally, in numerous randomized controlled trials, in-hospital diuretic intensification has not reduced the risk of major heart failure events, even when treatment is sustained. These findings, taken collectively, suggest that any immediate diuretic effects of acetazolamide and SGLT2 inhibitors in acute heart failure are not likely to influence the short- or long-term clinical course of patients.