Can lacosamide (antiepileptic medication) cause bradycardia?

Can Lacosamide Cause Bradycardia?

Yes, lacosamide can cause bradycardia and other cardiac conduction abnormalities, including atrioventricular (AV) block, through its mechanism of enhancing slow inactivation of voltage-gated sodium channels in cardiac tissue.

Mechanism and Clinical Evidence

Lacosamide's cardiac effects stem from its action on voltage-dependent sodium channels, which affects not only neuronal tissue but also cardiac conduction pathways 1. The drug primarily impacts non-sinusal cardiac tissue, with particular effects on the atrioventricular and infrahisian nodes 1.

Documented Cardiac Complications

Bradycardia and conduction abnormalities have been reported across multiple clinical contexts:

• In clinical trials for diabetic neuropathy, atrial fibrillation/flutter occurred in 1.5% of patients receiving lacosamide 600 mg/day, compared to 0% in placebo groups 2
• Complete atrioventricular block with extreme bradycardia requiring pacemaker placement has been documented, particularly when combined with other sodium channel blockers 1
• Second-degree AV block can develop rapidly—within hours of intravenous administration—even in healthy young adults with no cardiac comorbidities 3
• Severe bradycardia and shock with delayed onset (approximately 8.5 hours post-ingestion) has occurred in overdose cases, with serum levels reaching 91.5 µg/mL 4

High-Risk Populations and Scenarios

Exercise particular caution in the following situations:

• Patients with baseline bradycardia or early repolarization changes are exquisitely sensitive to lacosamide-induced conduction abnormalities, even at therapeutic doses 3
• Concomitant use with other sodium channel blockers (carbamazepine, eslicarbazepine) dramatically increases risk of high-degree AV block 1
• Elderly patients or those with pre-existing cardiac disease (ischemic heart disease, heart failure, history of AV block) should be considered contraindicated for lacosamide therapy 1
• Pediatric patients have experienced bradycardia, though the incidence appears lower; one study reported bradycardia in 1 of 9 children (11%) receiving IV lacosamide for status epilepticus 5

Monitoring Requirements

Implement the following surveillance protocol:

• Obtain a baseline 12-lead electrocardiogram before initiating lacosamide therapy 1, 3
• Perform regular electrocardiographic monitoring during the first few weeks of treatment, with particular attention to PR interval prolongation 1
• For intravenous administration, continuous cardiac monitoring is essential, as conduction changes can develop within hours 3
• Monitor for dose-dependent PR interval prolongation, which is a characteristic effect of lacosamide 3

Management of Lacosamide-Induced Bradycardia

When bradycardia or conduction abnormalities occur:

• Immediately discontinue lacosamide 1, 4
• Most patients with drug-induced bradycardia are asymptomatic and require only observation 2
• For symptomatic bradycardia with hemodynamic instability, initiate vasopressor support (dopamine infusion may be required at doses up to 10.5 µg/kg/min in severe cases) 4
• Temporary pacing should be considered for persistent hemodynamically unstable bradycardia unresponsive to medication discontinuation 6
• Permanent pacemaker implantation may be necessary for complete AV block, particularly when lacosamide cannot be discontinued and no alternative therapy exists 1

Contraindications and Precautions

Lacosamide should be contraindicated or used with extreme caution in:

• Patients with known atrioventricular block, ischemic heart disease, or heart failure 1
• Patients receiving other medications that prolong the PR interval 1
• Patients with severe sinus node dysfunction, marked sinus bradycardia, or second- or third-degree AV block (similar precautions as with amiodarone) 2

Alternative Administration Considerations

Recent evidence suggests that undiluted IV push administration over 5 minutes may be safe in selected patients, with hypotension or bradycardia occurring in 16.6% of lacosamide recipients in one cohort 7. However, this route still requires careful cardiac monitoring and should not diminish vigilance for conduction abnormalities 7.