This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
N terminal pro-brain natriuretic peptide levels are elevated in: 
Select and explain. 
A. Atrial fibrillation, B. Left heart failure, C. Pulmonary thromboembolism, D. Myocardial infarction
B: Left heart failure
Answer: B: Left heart failure 
Explanation: 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,