A 76-year-old man is referred by his family physician because of poor oral intake, weight loss, and severe fatigue over the past 2 weeks:

• Sinus tachycardia
• One premature ventricular complex
• Tall peaked T waves in the anterior leads (consider hyperkalemia)

His bloodwork showed evidence of acute renal failure, with a serum creatinine of 797 micromoles/L (normal range: 60-120 micromoles/L), hyperkalemia with a serum potassium of 6.6 mmol/L (normal range: 3.5-5 mmol/L), and severe normocytic anemia.

The patient was admitted to hospital, and his renal failure was vigorously treated. A diagnosis of multiple myeloma was made, and the patient received a course of melphalan. He was discharged from hospital after 2 weeks.

The patient was reassessed in the hematology clinic after 6 weeks. His clinical condition remained satisfactory, and he had no cardiac complaints:

• Lead I shows only very small r waves and no P or T waves (“collapsed lead I”)
• Leads II and III have identical pattern – the chest leads are normal
• Suspect lead placement error (Right Arm-Right Leg lead reversal, Left Arm-Left Leg lead reversal)

The patient is in the hematology clinic for reassessment 2 months later. He is still stable, and moderately active without symptoms:

• Sinus rhythm, 89/min
• Normal ECG
• The previous ECG (ECG 2) had been incorrectly recorded