Abstract
AIMS: Diuretic resistance (i.e., insufficient diuretic and natriuretic response to an appropriate dose of intravenously administered loop diuretic) is a major cause of insufficient decongestion in acute heart failure (AHF). Early assessment of diuretic and natriuretic response already after the first administration of loop diuretic is currently recommended, but few data exist on the prevalence and characteristics of upfront diuretic resistance in AHF. The aim of this sub-study of the P-Value-AHF randomized clinical trial was to investigate the prevalence and characteristics of upfront diuretic resistance in patients presenting with AHF in the emergency department (ED). METHODS: Consecutive patients presenting with a clinical diagnosis of AHF, ≥1 sign of congestion, and NT-proBNP >1000 ng/L between February and June 2024 were prospectively screened. Loop diuretics were administered per protocol: 40 mg furosemide i.v. in diuretic-naïve patients and those on oral torasemide <40 mg, 80 mg furosemide i.v. in patients on oral torasemide ≥40 mg daily. Urine output was measured over the following 2 h and in patients with urine volume <300 mL, urine sodium concentration was additionally measured in a spot sample. Upfront diuretic resistance was defined as urine volume <300 mL in 2 h and urine sodium concentration <70 mmol/L. RESULTS: From a total of 127 screened AHF patients presenting to the ED, 17 subjects were excluded after denial of informed consent and 17 could not be treated according to the protocol due to one or more exclusion criteria. Of the remaining 93 per-protocol-treated patients, 91 showed an adequate diuretic response either in terms of urine volume or urine sodium concentration. Only two of 93 patients (2.2%) met the criteria of upfront diuretic resistance. In a post-hoc analysis, patients with diuretic resistance had higher prevalence of chronic kidney or liver diseases, markedly lower blood pressure and heart rate, markedly higher serum creatinine and potassium levels, and lower serum sodium. Notably, clinical signs of congestion, circulating NT-proBNP, and left-ventricular ejection fraction were similar in both groups. CONCLUSIONS: Upfront diuretic resistance in an unselected population of AHF patients presenting to the ED affects only a minority of patients. These data highlight the importance of a standardized, protocolized approach to decongestive treatment in AHF, which includes the rapid administration of loop diuretics in an adequate dose. Pre-existing chronic kidney disease and high creatinine levels were more prevalent in patients with diuretic resistance.