A 57-year-old male with atrial fibrillation and reduced ejection fraction: correct dose of exercise prescription

The case

• A 57-year-old male was diagnosed with non-ischemic dilated cardiomyopathy associated with long standing permanent atrial fibrillation (AF). On presentation he was in New York Heart Association functional class III. On clinical examination, the heart rate was 75 bpm with a blood pressure of 115/80 mmHg. The chest was clear and there was no peripheral oedema. Cardiac auscultation revealed dual heart sounds with no additional murmurs.
• Associated co-morbidities: non-insulin-dependent diabetes mellitus and body mass index of 36.8 kg/m2, grade II obesity.
• The patient was on the following medical therapy: Losartan 100 mg od, Furosemide 40 mg od, Carvedilol 150 mg od, Warfarin according to INR, Simvastatin 20 mg od, Metformin 850 mg bid and Omeprazole 20 mg od.
• Echocardiography demonstrated a left ventricular ejection fraction was 35% (Simpson method), with diffuse myocardial hypokinesis, left ventricular diastolic dimension of 57mm, left atrial size of 54 mm. The right ventricular size was 37 mm (basal segment) with preserved systolic function. Pulmonary artery systolic pressure measured 35 mmHg. There were no significant valvular abnormalities.
• Cardiopulmonary exercise testing showed a VO_2peak 14.7 mL/Kg/min and a VE/VCO₂ slope 33