A 76-year-old man is brought to the emergency department in an unresponsive state.

Spironolactone is a potassium-sparing diuretic that can cause hyperkalemia, especially in patients with impaired renal function. Hyperkalemia can lead to life-threatening arrhythmias, particularly wide complex tachycardia or ventricular fibrillation.

Toronto Notes 2023 – Cardiology and Nephrology, “Hyperkalemia” Section:

“Patients with CKD are at increased risk for hyperkalemia, particularly when taking potassium-sparing medications such as spironolactone. Severe hyperkalemia may cause bradycardia or wide-complex tachyarrhythmias.”

MCCQE1 Objectives (Internal Medicine > 76-2: Electrolyte Abnormalities):

“Candidates must recognize drug-induced hyperkalemia as a cause of cardiac arrhythmias, especially in patients with renal dysfunction.”

Hydrochlorothiazide (B) can cause hypokalemia. Metoprolol (C) and diltiazem (E) are rate-controlling agents but do not typically cause wide complex tachycardia. Clopidogrel (D) has no effect on cardiac conduction.

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