Can gabapentin cause tachycardia or abnormal heart rhythms?

Gabapentin and Cardiac Arrhythmias

Yes, gabapentin can cause tachycardia and abnormal heart rhythms, particularly atrial fibrillation, especially in elderly patients and those with pre-existing cardiovascular conditions.

Evidence for Gabapentin-Associated Arrhythmias

Atrial Fibrillation Risk

• Recent evidence shows gabapentin is associated with an increased risk of atrial fibrillation, particularly in elderly populations
• A population-based cohort study found that new users of gabapentin had a 2.91-fold increased risk of initiating treatment for atrial fibrillation compared to opiate users 1
• The Multi-Ethnic Study of Atherosclerosis found gabapentinoid use was associated with:
  • 84% greater average frequency of premature atrial contractions per hour
  • 44% greater average number of runs of supraventricular tachycardia per day 2

Case Reports

• A case report documented atrial fibrillation developing in a young adult male just 4 days after starting gabapentin for lumbar radiculitis 3
• Another case report described cardiac complications including peripheral and central edema progressing to heart failure symptoms with pregabalin (a similar gabapentinoid), which resolved after discontinuation 4

Risk Factors for Gabapentin-Induced Arrhythmias

Higher risk populations include:

• Elderly patients (≥65 years)
• Patients with pre-existing cardiovascular disease
• Patients with renal impairment (gabapentin is primarily eliminated by the kidneys)
• Patients taking other medications that affect cardiac conduction 5
• Dose-dependent relationship (higher doses = greater risk) 1

Mechanism of Action

While the exact mechanism is not fully understood, gabapentin's effect on calcium channels may contribute to cardiac side effects:

• Gabapentin binds to the α2δ subunit of voltage-gated calcium channels
• This binding may affect cardiac conduction and rhythm regulation
• Similar mechanisms have been observed with pregabalin, which has a similar structure and mechanism of action 4

Monitoring Recommendations

For patients on gabapentin therapy:

1. Baseline cardiac assessment before initiating therapy, especially in high-risk patients
2. Regular monitoring for symptoms of arrhythmias (palpitations, dizziness, syncope)
3. ECG monitoring if symptoms develop or in high-risk patients
4. Dose adjustment based on renal function to prevent toxicity
5. Careful consideration when prescribing to patients with pre-existing cardiac conditions

Alternative Medications

If cardiac concerns exist, consider alternative medications for neuropathic pain:

• Duloxetine (SNRI) - first choice for central neuropathic pain 5
• Tricyclic antidepressants (with cardiac monitoring)
• Topical capsaicin for localized neuropathic pain 5

Clinical Pearls

• The risk of arrhythmias appears to be dose-dependent; consider using the lowest effective dose
• Renal impairment significantly increases gabapentin levels and potential for adverse effects
• Monitor for peripheral edema, which may be an early sign of cardiac complications 4
• Be particularly vigilant when prescribing to elderly patients or those with cardiac risk factors
• Consider drug interactions that may potentiate cardiac effects (e.g., amiodarone, as seen in a case report of extreme QT prolongation with combined gabapentinoid and amiodarone use) 6

While gabapentin is generally considered to have a favorable safety profile compared to some alternatives like opioids, clinicians should be aware of these potential cardiac effects and monitor appropriately, especially in high-risk populations.