A 75 year old man experienced a heart attack 1 year ago. In the past 1 month he states he has noted increased breathlessness on exertion. He states that he is now only able to walk about 100 metres before he must rest, but there is no chest pain. There is peripheral oedema of the legs bilaterally. He has Chronic Obstructive Pulmonary Disease and says he is compliant with his inhalers and all of his other medications. Bloods including a N-terminal pro-B-type natriuretic peptide level (NT-proBNP) level have been arranged which is elevated.
Which one of the following situations would not elevate his BNP level?