**6. Controversies in the use of natriuretic peptides for the verification of HF**

It is known that in HF, an increase in the level of natriuretic peptides is observed in the blood. They are natural antagonists of the renin-angiotensin-aldosterone system. This is a weapon with which the patient's body resists the onslaught of neurohumoral activity in HF. However, it is very difficult to interpret the increase in the activity of these substances in a patient 2–3 times in comparison with the upper limit of the norm.

Thus, the level of brain natriuretic peptide (BNP) in obese patients is one and a half times lower compared to people with normal body weight despite a similar severity of HF [11]. In patients with liver cirrhosis, N-terminal precursor of brain natriuretic peptide (NT-proBNP) plasma level may increase five times in comparison with the control [12]. In patients with renal insufficiency, standards for the content of NT-proBNP have been developed depending on age [13].

The Association between NT-proBNP and the probability of developing atrial fibrillation [14] can be interpreted as an increase in the level of NT-proBNP in patients after silent paroxysms of atrial fibrillation. That is, the NT-proBNP level will indicate that the patient has suffered acute cardiac dysfunction, and not the presence of HF.

Thus, the abundance of parameters that affect the concentration of NT-proBNP does not allow us to make a decision about the presence or absence of HF with a small increase in its level. NTproBNP provided a higher negative predictive values (0.97) than BNP (0.87), but at lower positive predictive values (0.44 versus 0.59) [15].

In summary, it can be argued that the absence of an increase in NTproBNP can be used to exclude the diagnosis of HF, but an increase within 3 HGN should be interpreted very carefully.

Soluble ST2 receptor is a marker of the severity of fibrosis, remodeling, inflammation, and volume load on the heart. It can claim to be a more accurate marker of CH dynamics in comparison with NTproBNP [16].

On the other hand, the practitioner does not need a predictor of the developing deterioration of the patient's condition. The dynamics of body weight indicates an occurring fluid retention and the need to increase the dose of diuretics and search for the cause. And life-saving medications, such as renin-angiotensin-aldosterone system blockers, should be given at targeted doses that are independent of such markers.
