Can gabapentin (anticonvulsant medication) cause bradycardia (abnormally slow heart rate)?

Gabapentin and Bradycardia: Clinical Considerations

Gabapentin can cause bradycardia, particularly with chronic use, through direct effects on cardiac calcium signaling pathways that can suppress cardiovascular function.

Mechanism and Evidence

Gabapentin, an anticonvulsant medication commonly used for neuropathic pain and seizures, has been associated with cardiovascular effects that can lead to bradycardia:

• Recent preclinical research demonstrates that both acute and chronic gabapentin treatment can cause significant bradycardia in rat models 1
• The mechanism appears to involve:
  • Direct effects on cardiac calcium signaling pathways
  • Upregulation of calmodulin in heart tissue
  • Suppression of cardiovascular function independent of central nervous system effects

Risk Factors and Clinical Considerations

Several factors may increase the risk of gabapentin-induced bradycardia:

• Age: Elderly patients are at higher risk for cardiovascular adverse effects
• Pre-existing cardiovascular disease: Patients with heart disease may be more susceptible
• Concomitant medications: Particular caution is needed when combining gabapentin with:
  • Beta-blockers
  • Non-dihydropyridine calcium channel blockers (verapamil, diltiazem)
  • Digoxin
  • Other medications with bradycardic effects 2, 3

Monitoring Recommendations

For patients on gabapentin therapy:

• Obtain baseline ECG before initiating treatment, particularly in patients with:
  • History of cardiovascular disease
  • Age >65 years
  • Concomitant use of other medications affecting heart rate
• Monitor heart rate and blood pressure regularly during dose titration
• Consider follow-up ECGs after significant dose increases
• Be vigilant for symptoms of bradycardia:
  • Dizziness
  • Fatigue
  • Syncope or pre-syncope
  • Exercise intolerance

Management of Gabapentin-Induced Bradycardia

If bradycardia develops:

1. Assess severity and symptoms:

   • Asymptomatic bradycardia >40 bpm generally doesn't require immediate treatment 3
   • Symptomatic bradycardia requires intervention

2. For symptomatic bradycardia:

   • Consider dose reduction or discontinuation of gabapentin
   • If severe or persistent:
     • Atropine 0.5-1 mg IV (may repeat every 3-5 minutes, maximum 3 mg) 3
     • For refractory cases: beta-agonists (dopamine, epinephrine) or temporary pacing 3

3. Alternative medications:

   • Consider alternative pain management strategies if appropriate
   • If gabapentin must be discontinued, slow tapering is preferable to sudden withdrawal

Other Cardiovascular Considerations with Gabapentin

Beyond bradycardia, gabapentin has been associated with:

• Atrial fibrillation, particularly in older adults but also reported in younger patients 4
• Heart failure risk, though this appears more significant with pregabalin than gabapentin 5
• Peripheral edema that may progress to central edema 6

Clinical Pearls

• The bradycardic effect of gabapentin appears to be dose-dependent
• Start with low doses and titrate slowly, especially in elderly patients or those with cardiovascular disease
• The cardiovascular effects of gabapentin may be underrecognized in clinical practice
• When evaluating unexplained bradycardia, consider gabapentin as a potential cause
• Patients with pre-existing sinus node dysfunction or conduction disorders may be at higher risk

While gabapentin is generally well-tolerated, clinicians should be aware of its potential to cause bradycardia and other cardiovascular effects, particularly in vulnerable populations.