 According to current guidelines, angiotensin converting enzyme inhibitors and beta-adrenolytics are the first-line treatment agents in patients with heart failure. In case of fluid retention, diuretics, as a part of symptomatic treatment, should be administered. In practice, the most common diuretic used in patients with heart failure is loop diuretic - furosemide. What is important, furosemide has no effect on patients outcomes. Some studies showed unfavourable influence of this drug on rennin-angiotensin-aldosterone system. 