Diltiazem (Cardizem) is Not Contraindicated in Hyperkalemia
Diltiazem (Cardizem) is not contraindicated in hyperkalemia, and in some cases may actually help reduce the rate of increase in plasma potassium levels in certain patients. 1
Evidence-Based Rationale
The 2016 ACC/AHA/HRS guidelines for the management of supraventricular tachycardia provide a comprehensive list of precautions and contraindications for diltiazem, which include:
- AV block greater than first degree
- SA node dysfunction (in absence of pacemaker)
- Hypotension
- Decompensated systolic heart failure/LV dysfunction
- WPW with atrial fibrillation/flutter
- Hepatic or renal dysfunction 2
Notably, hyperkalemia is not listed as a contraindication for diltiazem in these guidelines.
Relationship Between Diltiazem and Potassium Homeostasis
Research evidence actually suggests that diltiazem may have beneficial effects on potassium homeostasis:
- A 1992 study demonstrated that diltiazem reduced the rate of increase of plasma potassium during a 28-hour interdialytic period in patients with end-stage renal disease 1
- Unlike beta-blockers (particularly non-selective ones), calcium channel blockers like diltiazem are not known to worsen hyperkalemia 3
Clinical Considerations
When managing patients with hyperkalemia who may need diltiazem:
Monitor for bradycardia: Hyperkalemia itself can cause cardiac conduction abnormalities, and diltiazem has negative chronotropic effects. Combined, they could potentially exacerbate bradycardia 4
Consider drug interactions: Caution is needed when combining diltiazem with beta-blockers, as this combination may increase the risk of:
- Sinus arrest
- Atrioventricular block
- Bradycardia 5
Renal function: While hyperkalemia itself is not a contraindication, diltiazem should be used with caution in patients with renal dysfunction, which often accompanies hyperkalemia 2
Monitoring Recommendations
For patients with hyperkalemia receiving diltiazem:
- Monitor ECG for changes associated with hyperkalemia (peaked T waves, prolonged PR interval, widened QRS)
- Regular assessment of serum potassium levels
- Monitor heart rate and blood pressure
- Assess for signs of worsening cardiac conduction 3
Summary
Unlike non-selective beta-blockers which can worsen hyperkalemia, diltiazem is not contraindicated in hyperkalemia and may actually have beneficial effects on potassium handling in some patients. However, careful monitoring is essential, particularly when hyperkalemia is accompanied by ECG changes or when diltiazem is combined with other negative chronotropic agents.