The Changing Role of Loop Diuretics in Heart Failure Management across the Last Century

Congestion is the main therapeutic target of acute heart failure (HF) treatment, and loop diuretics (LDs) are widely used drugs for this purpose. Despite their extensive use, these agents remain largely understudied in terms of modality administration, treatment duration, and escalation dose for subjects responding poorly to therapy. LDs were initially investigated in several edematous statuses such as cirrhosis, nephrotic syndrome, and congestive HF and initially approved for the treatment of cardiogenic congestion in 1966. Despite the long history and the undoubted role in congestion management, the use of LDs in the acute phase is mostly based on the physician's experience, the oral amount chronically administered, and clinical decongestion response. Recent literature suggests monitoring diuretic activity by the evaluation of daily diuresis, weight loss, and sample urinary sodium assessment after early intravenous LD administration. More recently, the measurement of urinary sodium integrated with urinary and blood creatinine values and fluid status has been suggested as optimal marker to predict whole diuretic efficiency and to target the optimal dose. However, this method is not easily available in the chronic setting or in patients with recurrent hospitalization taking a high loop diuretic amount. Since high loop diuretic dose is related to diuretic resistance (DR) and poorer outcome, additional diuretics acting in different nephron sites are often required. Current sequential nephron blockade can stimulate diuresis by synergic mechanisms. This strategy is attempted in patients with poor response, revealing good results in the early period, but the effects of neuro-endocrine stimulation and electrolyte balance across long-term follow-up are still questioned. This paper reviews the historical course of loop diuretics and highlights the need for a universal approach based on clinical conditions, cardio-renal interactions, and HF phenotypes.