Ventricular arrhythmia during ajmaline challenge for the Brugada syndrome

Abstract

The Brugada syndrome is a genetic disease characterized by an abnormal electrocardiogram (ECG) and an elevated risk of sudden cardiac death. Sodium channel blockers (SCBs), such as ajmaline, are used to unmask the characteristic type 1 Brugada electrocardiographic pattern. We review the literature on the incidence of ventricular arrhythmia (VA) during SCB challenge. We evaluate the clinical and electrocardiographic characteristics of these patients as well as their prognosis. All articles published from January 2000 until August 2015, in which the incidence and predictors of VAs during SCB challenge were reported, are reviewed. The occurrence of VA during SCB challenge ranges from 0 to 17.8%. The weighted average for induction of any VA during sodium blocking challenge is 2.4%; for non-sustained ventricular tachycardia (VT), it is 0.34% and for sustained VT 0.59%. No fatal cases were reported. Predictors may be young age, conduction disturbance at baseline ECG, and mutations in the SCN5A gene. All other clinical and electrocardiographic characteristics failed to be consistent predictors. Life-threatening arrhythmias during SCB challenge are not an exceptional event. Therefore, provocation testing must necessarily be performed in an appropriate environment in which advanced life support facilities are present. Patients who have a higher risk for induced arrhythmias might be those who display a conduction disturbance at baseline ECG or have certain SCN5A mutations or are of a younger age. However, survivors of these induced arrhythmias do not seem to suffer from a worse prognosis.

Keywords: Ajmaline challenge; Brugada syndrome; Proarrhythmia; Sodium channel blocker challenge; Ventricular arrhythmias.