The limitations of diuretics in the treatment of acute decompensated heart failure (ADCHF) are progressive worsening of renal function and resistance to up-titrated doses. The occurrence of resistance to loop diuretics in patients with ADCHF is associated with worsening prognosis and increased mortality. In this study, we report two patients with ADCHF and resistance to loop diuretics suspected for venous thromboembolism, suggesting that heparin administered to ADCHF patients treated for venous thromboembolism with cardiorenal syndrome decreases right-ventricular overload and improves renal function. To our knowledge, these are the first reported cases describing restored responsiveness to loop diuretics in ADCHF patients after additional heparin administration.