Loop diuretics for chronic heart failure: a foe in disguise of a friend?

Loop diuretics are recommended for relieving symptoms and signs of congestion in patients with chronic heart failure and are administered to more than 80% of them. However, several of their effects have not systematically been studied. Numerous cohort and four interventional studies have addressed the effect of diuretics on renal function; apart from one prospective study, which showed that diuretics withdrawal is accompanied by increase in some markers of early-detected renal injury, all others converge to the conclusion that diuretics receipt, especially in high doses is associated with increased rates of renal dysfunction. Although a long standing perception has attributed a beneficial effect to diuretics in the setting of chronic heart failure, many cohort studies support that their use, especially in high doses is associated with adverse outcome. Several studies have used propensity scores in order to match diuretic and non-diuretic receiving patients; their results reinforce the notion that diuretics use and high diuretics dose are true risk factors and not disease severity markers, as some have suggested. One small, randomized study has demonstrated that diuretics decrease is feasible and safe and accompanied by a better prognosis. In conclusion, until elegantly designed, randomized trials, powered for clinical endpoints answer the unsettled issues in the field, the use of diuretics in chronic heart failure will remain subject to physicians' preferences and biases and not evidence based.