MRCP2-3802

A 52-year-old man presents to the Emergency Department (ED) with ankle swelling and general malaise. He reports a recent decrease in exercise tolerance due to increasing breathlessness and a productive cough. On examination, he has a raised JVP, bipedal oedema, and bi-basal crackles. Investigations reveal an enlarged heart with evidence of fluid overload on CXR, and a dilated left ventricle with moderate global impairment of function on ECHO. Which factor would have the greatest impact on his long-term prognosis?