No large-scale randomized, placebo-controlled trials evaluate furosemide's effect on mortality and long-term morbidity in diastolic or systolic dysfunction. In short-term studies, furosemide reduces edema, reduces hospitalizations, and improves exercise capacity in the setting of systolic dysfunction (strength of recommendation [SOR]: B, based upon low-quality randomized controlled trials). Furosemide and other diuretics reduce symptomatic volume overload in diastolic and systolic dysfunction (SOR: C, based on expert opinion). There is potential morbidity with the use of high-dose loop diuretics (volume contraction, electrolyte disturbances, and neuroendocrine activation). Use of high-dose loop diuretics for systolic dysfunction is associated with increased mortality, sudden death, and pump failure death (SOR: B, based on retrospective analyses of large-scale randomized controlled trials). However, diuretic resistance or disease severity may explain these latter findings.