N terminal pro-brain natriuretic peptide levels are elevated in:
In left heart failure, left ventricle releases N terminal pro-BNP and it is used as a marker for left ventricular failure.
Measurement of brain natriuretic peptide levels in serum is increasingly used to assess for CHF in patients presenting with acute dyspnea, but may be elevated in the presence of right ventricular strain as well.
Plasma levels of N-terminal pro brain natriuretic peptide moderately correlate with carcinoid heart disease severity.
Reference: Harrison’s P R I N C I P L E S   O F I N T E R N A L M E D I C I N E 20th edition page no 1740,
Atrial fibrillation
Left heart failure
Pulmonary thromboembolism
Myocardial infarction