A 70-year-old male was referred by his GP for management of congestive heart failure, which was diagnosed recently. History Poorly controlled hypertension Deteriorating shortness of breath, fatigue and orthopnea for the last three months Medications since last one month: digoxin (62.5 mg daily), frusemide (80 mg daily), and amiloride (10 mg) Examination Pulse: 96b pm Blood pressure: 132/88 mmHg JVP not raised, some scattered bibasal crackles on auscultation with a displaced apex beat in the anterior axillary line, 6th intercostal space Auscultation of the heart revealed no murmurs Peripheral oedema to the mid tibia Investigation Electrolytes normal Serum urea concentration: 17 mmol/l (NR 2-8 mmol/l) Creatinine: 175 µmol/l (NR 55-110 µmol/l) Serum digoxin-:0.7 ng/mL (therapeutic: 1.0–2.0) One month earlier, urea: 11 mmol/l and creatinine: 110 µmol/l ECG reveals left ventricular…