Arrhythmias induced by dextrose‐insulin challenge test in nondiagnostic Brugada ECG patterns

Introduction Dynamic ECG changes in Brugada syndrome (BrS) are influenced by several factors, may not be apparent, and can be unmasked by a drug test. Methods and Results Four of six patients with nondiagnostic Brugada ECG index patterns underwent a dextrose‐insulin challenge test that resulted in J‐ST segment elevation and triggered arrhythmias. Conclusion Insulin action may be due in part to an outward shift in the K+ current at the end of action potential phase 1 and the dispersion of repolarization, leading to local re‐entry with arrhythmogenicity. This effect is likely a phenomenon‐specific to BrS.