N-terminal fragment of the prohormone B-type natriuretic peptide (NT-proBNP) is a neurohormone secreted from certain cardiac muscle cells in response to cardiovascular stress. Elevated NT-proBNP levels indicate the presence of ongoing cardiac stress and potentially an underlying, possibly unsuspected, cardiovascular disorder. Addressing the source of cardiac stress through appropriate therapy will reduce NT-proBNP levels to normal. At The Heart Attack Prevention Institute (HAPI) of Naples, FL, testing to determine NT-proBNP levels is performed using a small sample of the patient's blood (LINK TO BERKELEY HEARTLAB WEBSITE).