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Sina Safabakhsh¹, Andrew D Krahn¹, Zachary Laksman¹

¹Division of Cardiology, University of British Columbia, Vancouver, British Columbia, Canada.

|September 10, 2021

Summary

Flecainide can unmask a Brugada pattern during exercise stress tests in patients with early repolarization. This drug-induced pattern, observed at higher heart rates, aids in diagnosing Brugada syndrome.

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Area of Science:

Cardiology
Clinical Electrophysiology
Pharmacology

Background:

Early repolarization is a common finding on electrocardiograms.
Symptomatic atrial arrhythmias require treatment, often with antiarrhythmic drugs.
Brugada syndrome is a genetic disorder affecting the heart's electrical system.

Observation:

A young man with early repolarization developed a type 1 Brugada electrocardiogram pattern during a treadmill stress test while on flecainide and diltiazem.
The Brugada pattern emerged at higher heart rates.
Genetic testing and family history did not reveal underlying Brugada syndrome.

Findings:

Flecainide, an antiarrhythmic drug, can exhibit use-dependent properties.
This use-dependent effect can unmask a Brugada pattern, particularly at faster heart rates.
Exercise stress testing can provoke this drug-induced Brugada pattern.

Implications:

Exercise stress testing can be a valuable tool for diagnosing Brugada syndrome in select patients.
Understanding flecainide's use-dependent properties is crucial for interpreting electrocardiogram changes.
This case highlights the importance of considering drug effects when evaluating cardiac arrhythmias and ECG abnormalities.