23rd May 2025

A 73 year old man presents to the emergency department with a four month history of worsening bilateral lower leg oedema and new shortness of breath.

A 73 year old man presents to the emergency department with a four month history of worsening bilateral lower leg oedema and new shortness of breath. His past medical history includes type 2 diabetes mellitus, hypertension, and angina. The regular medications include metformin, lisinopril, glyceryl trinitrate spray and aspirin. On examination, his blood pressure is 110/75 mmHg and his pulse rate is 60/min. Jugular venous distension is noted along with symmetric 2+ pitting oedema in both legs. Cardiac examination reveals a regular rate, no murmurs and the chest is clear. A chest radiograph shows mild interstitial oedema and cardiomegaly. Which of the following is the most important next step in diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.