INTRODUCTION: Mortality from heart failure remains high. Many subjects who have been hospitalised with acute decompensated heart failure leave hospital with residual congestion, despite treatment with loop diuretics. In an attempt to improve this, the Acetazolamide in Decompensated heart failure with Volume OveRload (ADVOR) trial was undertaken, where acetazolamide was added to the loop diuretic bumetanide. AREAS COVERED: This article discusses ADVOR. The primary endpoint of ADVOR was the reversal of congestion, which was increased by adding acetazolamide to bumetanide. However, acetazolamide did not shorten hospital stay or the composite of rehospitalisation and death after three months. EXPERT OPINION: The limitations of ADVOR include that acetazolamide did not improve quality of life and that the testing was in white subjects only. During the hospital stay for decompensation, medicines that inhibit the angiotensin and mineralocorticoid systems were increased, which suggests that the treatment for heart failure was not ideal on hospitalisation. As the death rates in ADVOR were lower than in previous studies, this suggests that the overall treatment of decompensated/heart failure is improving. However, in the author's opinion, although the addition of acetazolamide is a small improvement in the treatment of acute decompensated heart failure with volume overload, more options need to be considered.