Is trazodone safe to use in patients with heart block?

Trazodone Use in Patients with Heart Block

Trazodone should be avoided in patients with heart block due to its potential to cause cardiac arrhythmias and worsen conduction abnormalities. 1

Cardiac Risks of Trazodone

• The FDA label explicitly warns that trazodone may be arrhythmogenic in patients with preexisting cardiac disease, including symptomatic bradycardia and conduction abnormalities 1
• Trazodone can cause various cardiac conduction disturbances, including:
  • Isolated PVCs and ventricular couplets 1
  • QT interval prolongation 1
  • Tachycardia with syncope 1
  • Torsade de pointes 1
  • Various forms of heart block 2

Evidence of Heart Block Risk

• Case reports document complete heart block occurring within 40 minutes after a single starting dose of trazodone in patients with risk factors for conduction delay 2
• Severe trazodone overdose has been associated with variable degrees of atrioventricular nodal blocks occurring 12-24 hours after ingestion 3
• While early studies suggested trazodone had little effect on cardiac conduction, subsequent clinical experience has shown it can cause severe conduction abnormalities in susceptible individuals 2

Guidelines for Patients with Conduction Disorders

• The 2018 ACC/AHA/HRS guideline on bradycardia and cardiac conduction delay recommends that patients with transient or reversible causes of atrioventricular block, such as drug toxicity, should have the offending agent discontinued 4
• For patients with symptomatic second-degree or third-degree atrioventricular block who require antidepressant therapy, permanent pacing may be reasonable if the medication cannot be discontinued 4
• Medications that can cause sinus node dysfunction, atrioventricular block, or bundle-branch block should be avoided in patients with existing conduction disorders 4

Alternative Approaches

• For patients requiring treatment for depression or insomnia who have heart block:
  • Consider alternative antidepressants with fewer cardiac conduction effects 5
  • Start with lower doses if an alternative to trazodone cannot be found 5
  • Implement cardiac monitoring during initiation of therapy 5
  • Consider permanent pacing if the medication is deemed necessary and cannot be discontinued 4

Special Considerations

• Trazodone may interact with other QT-prolonging medications, increasing the risk of serious arrhythmias 1
• Patients with electrolyte abnormalities (hypokalemia, hypomagnesemia) are at increased risk for trazodone-induced arrhythmias 1
• Trazodone should be avoided during the initial recovery phase of myocardial infarction 1
• The risk of cardiac complications appears dose-dependent, with lower doses (100-300 mg) being better tolerated in patients with cardiovascular disease 5

Clinical Decision Algorithm

1. Assess for presence and severity of heart block
2. If any degree of heart block is present, avoid trazodone if possible 1, 2
3. If treatment for depression/insomnia is necessary:
   • Choose alternative agents without cardiac conduction effects 5
   • If no suitable alternative exists and trazodone must be used:
     • Consider permanent pacing before initiating therapy 4
     • Start with lowest possible dose 5
     • Implement close cardiac monitoring 5
     • Monitor for symptoms of worsening conduction (syncope, presyncope, dizziness) 1

In conclusion, the evidence strongly suggests that trazodone poses significant risks in patients with heart block and should generally be avoided in this population unless absolutely necessary and with appropriate cardiac monitoring and intervention.