Impact of Clinical, Demographic and Laboratory Variables on Brain Natriuretic Peptide Levels

Brain natriuretic peptide (BNP), forms together with atrial natriuretic peptide (ANP) a peptide family involved in the regulation of blood pressure and fluid volume. It is used for the early diagnosis of heart failure (HF) in patients presenting to the emergency room with dyspnea. Additionally, in patients with chronic HF and acute and chronic coronary syndrome, BNP is a marker of unfavorable prognosis, being associated with increased mortality.

Recently, elevated BNP levels have been measured in patients with septic shock and have been attributed to myocardial dysfunction due to sepsis. Because BNP synthesis is also induced by endotoxin and inflammatory mediators, the mechanisms leading to elevated BNP levels in patients with sepsis remain unclear.

Interleukin-6 (IL-6) is a cytokine marker of inflammation that exhibits significant prognostic value in predicting severity and outcome of sepsis, since it is considered to play a key role in the pathogenesis of sepsis. Accumulating evidence suggests that inflammatory cytokines play an important role in the development of heart failure. In particular, studies using genetically engineered animal models have demonstrated the critical role of the gp130-dependent cardiomyocyte survival pathway in the transition to heart failure. However, the significance of gp130 for patients with CHF has not been fully assessed. Previous clinical studies showed that the plasma level of IL-6 is elevated in patients with advanced CHF and that such high levels are associated with a poor prognosis for CHF patients.

Procalcitonin (PCT) is a propeptide of calcitonin which is normally produced in the C-cells of the thyroid glands. Although physiologic levels of PCT remain very low, a dramatic increase in serum PCT levels is observed during severe systemic infections. It is not infection per se but infection accompanied by severe systemic reactions or poor organ perfusion that increases procalcitonin levels. These properties make procalcitonin less useful for the diagnosis of simple infections but a very promising marker of severe infections especially in the critical care setting.

Few studies have investigated the role of procalcitonin in patients with acute heart failure, although there was a slightly increased level of procalcitonin in patients with severe acute heart failure, the results were not conclusive. These results support the hypothesis that inflammatory process has a role in heart failure.