NPPB and Left ventricular diastolic dysfunction: Like other natriuretic peptides, the serum concentration of NT-proBNP increases as a response to increased left ventricular myocardial wall stress.25,26 NT-proBNP levels increased in patients with disorders causing left ventricular diastolic dysfunction, but this increase in NT-proBNP was not as much as that seen in left ventricular systolic dysfunction.27