Diuretic Response and Effects of Diuretic Omission in Ambulatory Heart Failure Patients on Chronic Low Dose Loop Diuretic Therapy

AIMS To study the loop diuretic (LD) response and effect of LD omission in ambulatory heart failure (HF) patients on chronic low dose LD. METHODS AND RESULTS Urine collections were performed on 2 consecutive days in 40 ambulatory HF patients with 40-80 mg furosemide (day 1 with LD; day 2 without LD). Three phases were collected each day: (1) first 6 hours; (2) rest of the day; and (3) night. On the day of LD intake, the total natriuresis was 129.9 (86.9-155.0) mmol/24h and urine output was 1650 (1380-2025) mL/24h. There was a clear LD response with a natriuresis of 9.4 (6.7-15.9) mmol/h and a urine output of 117 (83-167) mL/h during the first 6 hours, followed by a significant drop in natriuresis and urine output during the rest of the day (2.6 [1.8-4.8] mmol/h and 55 [33-71] mL/h) and night (2.2 [1.6-3.5] mmol/h and 44 [34-73] mL/h). On day 2, after LD omission, the natriuresis and urine output remained similarly low the entire day, resulting in a 50% reduction in natriuresis (55.1 [33.5-77.7] mmol/24h; p<0.001) and a 31% reduction in urine output (1035 [875-1425] mL/24h; p<0.001) compared with the day of LD intake. CONCLUSION HF patients on chronic LD treatment still have a clear diuretic response phase, while LD omission leads to a significant drop in natriuresis and urine output, arguing against routine cessation of low dose LD.