Diagnostic tests for rheumatologic diseases, amyloidosis, or pheochromocytoma are reasonable in patients presenting with HF in whom there is a clinical suspicion of these diseases. (Level of Evidence: C) See Table 6 for a summary of recommendations from this section. A. Ambulatory/Outpatient CLASS I 1. In ambulatory patients with dyspnea, measurement of B- type natriuretic peptide (BNP) or N-terminal pro-B-type natriuretic peptide (NT-proBNP) is useful to support clin- ical decision making regarding the diagnosis of HF, espe- cially in the setting of clinical uncertainty (64 70). (Level of Evidence: A) 2. Measurement of BNP or NT-proBNP is useful for establishing prognosis or disease severity in chronic HF (69,71 76). (Level of Evidence: A) CLASS IIa 1. BNP- or NT-proBNPLguided HF therapy can be useful to achieve optimal dosing of GDMT in select clinically euvole- mic patients followed in a well-structured HF disease management program (77 84). (Level of Evidence: B) CLASS IIb 1. The usefulness of serial measurement of BNP or NT-proBNP to reduce hospitalization or mortality in patients with HF is not well established (77 84). (Level of Evidence: B) 2. Measurement of other clinically available tests such as biomarkers of myocardial injury or brosis may be consid- ered for additive risk strati cation in patients with chronic HF (85 91). (Level of Evidence: B) B. Hospitalized/Acute CLASS I 1. Measurement of BNP or NT-proBNP is useful to support clinical judgment for the diagnosis of acutely decom- pensated HF, especially in the setting of uncertainty for the diagnosis (92 98). (Level of Evidence: A) Table 5. 