OBJECTIVE: Worsening renal function (WRF) is a frequent complication in acute heart failure (AHF) with a controversial prognostic value. We aimed to study the usefulness of natriuresis to evaluate WRF.
METHODS: We conducted an observational, prospective, multicenter study of patients with AHF who underwent a furosemide stress test. The patients were classified according to whether WRF was present or absent and according to the median natriuretic response. The main endpoint was the combination of mortality, rehospitalization due to HF, and heart transplant at 6 months of follow-up.
RESULTS: One hundred and fifty-six patients were enrolled, and WRF occurred in 60 (38.5%). The patients were divided into 4 groups: a) 47 (30.1%) no WRF/low UNa (UNa ≤ 109 mEq/L); b) 49 (31.4%) no WRF/high UNa (UNa >109 mEq/L); c) 31 (19.9%) WRF/low UNa and d) 29 (18.6%) WRF/high UNa. The parameters of the WRF/low UNa group showed higher clinical severity and worse diuretic and decongestive response. The development of WRF was associated with a higher risk of the combined event (HR, 1.88; 95%CI, 1.01-3.50; P=.046). When stratified by natriuretic response, WRF was associated with an increased risk of adverse events in patients with low natriuresis (HR, 2.28; 95%CI, 1.15-4.53; P=.019), but not in those with high natriuresis (HR, 1.18; 95%CI, 0.26-5.29; P=.826).
CONCLUSIONS: Natriuresis could be a useful biomarker for interpreting and prognosticating WRF in AHF. WRF is associated with a higher risk of adverse events only in the context of low natriuresis.

BACKGROUND: We aimed to describe the thiamine status in hospitalized hypervolemic heart failure (HF) and/or renal failure (RF) patients treated with furosemide and to investigate whether there was a difference in furosemide-related thiamine deficiency between patients with RF and HF.
METHODS: Patients who were diagnosed as hypervolemia and treated with intravenous furosemide (at least 40mg/day) were included in this prospective observational study. Whole blood thiamine concentrations were measured 3 times during hospital follow-up of patients.
RESULTS: We evaluated 61 hospitalized hypervolemic patients, of which 22 (36%) were men and 39 (64%) were women, with a mean age of 69.00±10.39 (45-90) years. The baseline and post-hospital admission days 2 and 4 mean thiamine levels were 51.71±20.66ng/ml, 47.64±15.43ng/ml and 43.78±16.20ng/ml, respectively. Thiamine levels of the hypervolemic patients decreased significantly during the hospital stay while furosemide treatment was continuing (p=0.029). There was a significant decrease in thiamine levels in patients who had HF (p=0.026) and also, thiamine was significantly lower in HF patients who had previously used oral furosemide before hospitalization. However, these findings were not present in patients with RF.
CONCLUSIONS: Thiamine substantially decreases in most hypervolemic patients receiving intravenous furosemide treatment during the hospital stay. Thiamine levels were significantly decreased with furosemide treatment in especially HF patients, but the decrease in thiamine levels did not detected at the same rate in RF patients. Diuretic-induced thiamine loss may be less likely in RF patients, probably due to a reduction in excretion.

Although treatment of acute heart failure is based primarily on the administration of intravenous loop diuretics, evidence supporting this practice is still scarce and there is uncertainty about the optimal dose. The existence of a considerable percentage of patients refractory to diuretic therapy and worsening of renal failure associated with the use of these drugs, with possible implications for medium-term mortality, have prompted the search for more effective and safer alternatives. Extracorporeal purification techniques, such as ultrafiltration, have demonstrated efficacy, although their superiority is unclear, due to the possible adverse effects associated with the procedure. The use of low-dose dopamine is not superior to conventional diuretic therapy after the first few hours of treatment. Moreover, combination with furosemide and hypertonic saline could be a valid alternative for patients with refractory congestion and depressed ejection fraction and serum creatinine ≤ 2.5mg/dL, but further studies are needed before its widespread use. The use of tolvaptan may be an effective alternative in the short-term but its use may be limited by its price. There is still controversy about whether treatment with loop diuretics is associated with higher mortality in all groups of patients with HF exacerbations. These controversies should be clarified by future clinical trials.

Diuretics are widely recommended in patients with acute heart failure (AHF). Unfortunately, despite their widespread use, limited data are available from randomized clinical trials to guide clinicians on the appropriate management of diuretic therapy. Loop diuretics are considered the first-line diuretic therapy, especially intravenous furosemide, but the best mode of administration (high-dose versus low-dose and continuous infusion versus bolus) is unclear. When diuretic resistance develops, different therapeutic strategies can be adopted, including combined diuretic therapy with thiazide diuretics and/or aldosterone antagonists. Low or \"non-diuretic\" doses (25-50mg QD) of aldosterone antagonists have been demonstrated to confer a survival benefit in patients with heart failure and reduced ejection fraction and consequently should be prescribed in all such patients, unless contraindicated by potassium and/or renal function values. There is less evidence on the use of aldosterone antagonists at higher or \"diuretic\" doses (≥ 100mg QD) but these drugs could be useful in relieving congestive symptoms in combination with furosemide. Thiazide diuretics can also be helpful as they have synergic effects with loop diuretics by inhibiting sodium reabsorption in distal parts of the nephron. The effect of diuretic therapy in AHF should be monitored with careful observation of clinical signs and symptoms of congestion. Serum electrolytes and kidney function should also be monitored during the use of intravenous diuretics.