A 44 year old man presents with worsening exertional dyspnea and fatiguability for 6 months, which has now progressed to dyspnea at rest. He also complains of orthopnea and paroxysmal nocturnal dyspnea but is otherwise asymptomatic.
His medical history is unremarkable, while there is no family history of cardiac disease. He is a heavy alcoholic, having consumed around 10 drinks per day for the last 20 years. His full blood count shows macrocytosis and a mild thrombocytopenia.