What conditions are Diltiazem (Diltiazem) contraindicated in?

Diltiazem Contraindications

Diltiazem is contraindicated in patients with sick sinus syndrome or second/third-degree AV block (unless a functioning ventricular pacemaker is present), hypotension (less than 90 mmHg systolic), hypersensitivity to the drug, and acute myocardial infarction with pulmonary congestion. 1

Absolute Contraindications

• Sick sinus syndrome without a functioning ventricular pacemaker 1, 2
• Second or third-degree AV block without a functioning ventricular pacemaker 1, 3
• Hypotension (less than 90 mmHg systolic) 1, 3
• Hypersensitivity to diltiazem 1
• Acute myocardial infarction with pulmonary congestion documented by x-ray on admission 1
• Wolff-Parkinson-White (WPW) syndrome with atrial fibrillation/flutter 3, 2
• Decompensated systolic heart failure or severe LV dysfunction 3, 2
• Cardiogenic shock 3

Use with Caution (Relative Contraindications)

• Concomitant use with beta-blockers - may cause significant bradyarrhythmias and heart failure 4, 5
• Hepatic dysfunction - diltiazem is metabolized by the liver 3, 2
• Renal dysfunction - may require dose adjustment 3, 2
• First-degree AV block - risk of progression to higher-degree block 4
• Bradycardia - may be exacerbated 4, 6
• Medications with SA/AV nodal-blocking properties - increased risk of conduction abnormalities 3

Drug Interactions to Consider

• CYP3A4 substrates and inhibitors - diltiazem is both a substrate of CYP3A4 and a moderate CYP3A4 inhibitor 3, 2
• Specific medications requiring caution:
  • Apixaban, itraconazole, bosutinib, ceritinib, cilostazol, cyclosporine, everolimus 3, 2
  • Ibrutinib, idelalisib, ivabradine, lomitapide, olaparib 3, 2
  • Ranolazine, rifampin, simeprevir, voriconazole 3, 2

Monitoring Recommendations

• Blood pressure and heart rate - monitor regularly, especially during dose titration 2
• ECG monitoring - particularly in patients with known conduction system disease 4
• Signs and symptoms of heart failure - especially in patients with pre-existing ventricular dysfunction 2, 5
• Liver function tests - if clinically indicated 2

Clinical Pearls

• In patients where beta-blockers are contraindicated for angina or hypertension, diltiazem may be an appropriate alternative, but not if LV dysfunction is present 7
• The risk of developing serious conduction abnormalities is higher when diltiazem is combined with beta-blockers, requiring careful monitoring 4, 5
• Peripheral edema is a common side effect that may be managed with the addition of diuretics 2
• Diltiazem can be effective for rate control in supraventricular tachyarrhythmias, but must be used with caution in patients with structural heart disease 8

Remember that the presence of multiple relative contraindications may compound risk and should be considered as potentially absolute contraindications in certain clinical scenarios.