This 68-year-old woman is in hospital for treatment of severe congestive heart failure secondary to rheumatic valvular disease:

• Atrial fibrillation – ventricular rate 66/min
• Incomplete right bundle branch block (iRBBB)
• ST depression, prominent U waves, with marked QT-U prolongation (QTU 612ms – cQTU 641ms)
• Hypokalemia should be strongly considered

Urgent bloodwork was sent off, and she was found to have a potassium of 2.2 mmol/L.