MRCP2-2066
A 50-year-old male presents with persistent diarrhoea and shortness of breath similar to his childhood asthma for the past 4 weeks. He has a history of smoking 10 cigarettes per day for 30 years and works as a builder. He drinks minimal alcohol and has no other medical history. On examination, he has a red face, no clubbing, and a soft and non-tender abdomen. A mid diastolic murmur is heard at the left sternal border during cardiovascular examination. His blood pressure is 86/49 mmHg, heart rate is 112 beats/min, sats are 96% on air, and respiratory rate is 20 breaths/min. What test would be the most diagnostic?