Abstract Background Congestion and volume overload are strongly associated with low quality of life and pose a significant risk for both rehospitalization and mortality in heart failure (HF) patients. Despite the widespread use of diuretics in HF, the use of weekly, intravenous (IV), high-intensity diuretic treatment has not been prospectively studied in the setting of ambulatory congestion-refractory patients. Purpose To assess the efficacy and safety of weekly high-intensity diuresis regimens in a practical setting of ambulatory day care for chronically congested HF patients. Methods We performed a sub-analysis on data from a prospective, randomized, cross-over controlled study (DEA-HF) originally designed to compare diuresis regimens in the setting of an HF ambulatory daycare unit who had signs of congestion or volume overload despite adherence to guideline-directed medical therapy. Each patient received three different IV diuretic regimens, in one of six randomized sequences: IV furosemide 250mg; IV furosemide 250mg + oral metolazone 5mg; and IV furosemide 250mg + IV acetazolamide 500mg. All regimens given on the same chronological week were pooled, and diuresis efficacy was assessed by measuring excreted urine volume and sodium weight 6 hours post treatment initiation. Additional assessment at one week post each treatment included serum levels of NT-ProBNP, body weight and creatinine as well as congestion score based on the presence of ascites, pleural effusion and pedal edema. Statistical analysis was based on linear mixed models while accounting for the random effect of patient identity. Results A total of 42 patients were recruited. The mean age was 72±9 years, twenty-one subjects (50%) had LVEF ≥ 50%. 74% of patients were NYHA III class. All patients were on contemporary guidelines-directed HF therapy. Analysis of excreted sodium weight and urine volume revealed values of 4202.1±180.1 mg (Mean±SEM) and 1.77±0.07 liter per visit, respectively. No significant differences in efficacy were detected among treatments given in consecutive weeks (P= 0.80 and 0.69 for differences in sodium weight and urine volume, respectively). After 4 weeks, log(NT-ProBNP) was significantly decreased (P=0.044), accompanied by a significant decrease of 2.4±0.62 kg in body weight (P=0.0004) and of 0.92±0.44 points in congestion score (P=0.037). Serum creatinine level was only slightly increased by 0.19±0.04 mg/dl (P=0.0001), demonstrating the overall safety of the high-intensity diuresis strategy. Conclusions In ambulatory, congestion refractory HF patients a strategy based on high-intensity, weekly diuresis therapy was safe and effective for three consecutive weeks. The natriuresis response to the treatments was maintained, NT-ProBNP levels and congestion score were decreased. The strategy may be instrumental for ambulatory HF patients that require diuretic therapy intensification and may allow to prevent hospitalization.