Which test is considered a definitive marker for early heart failure?

B-type natriuretic peptide (BNP) is recognized as a definitive marker for early heart failure due to its physiological role and its elevated levels in response to cardiac stress and dysfunction. When the heart is unable to pump blood effectively, the myocardial walls stretch, leading to the release of BNP from the ventricles.

In a clinical context, measuring the levels of BNP can help differentiate heart failure from other conditions that may present with similar symptoms, such as dyspnea. Elevated BNP levels are particularly advantageous because they can be detected relatively early in the course of heart failure, providing crucial information about heart function and guiding diagnosis and treatment decisions.

In contrast, other markers listed, such as CK, AST, CK-MB, and troponin, are more associated with myocardial injury and infarction rather than specifically indicating heart failure. While troponin can indicate cardiac muscle injury and could indicate a heart failure scenario, BNP directly reflects heart failure condition itself, making BNP a more definitive choice for confirming early heart failure.