Atypical right bundle brunch block and cardiac arrhythmias during exercise stress testing

Background: Atypical right bundle brunch block may conceal potentially lethal arrhythmogenic canalopathy known as Brugada syndrome. This disorder is characterised by dynamic electrocardiographic patterns, ranging from type I to type II and type III. The typical arrhythmia is a rapid polymorphic ventricular tachycardia but an increased propensity to atrial fibrillation has been documented, as well. Cardiac events occur mostly at the time of parasympathetic predominance. Purpose: In patients with atypical right bundle brunch block perhaps cardiac arrhythmias might occur during parasympathetic reactivation post exercise? Method: A group of forty eight patients with an electrocardiogram consistent with type II and type III Brugada ECG patters was observed during exercise stress testing. Patients were off medication at the time of the procedure. Special attention was payed to occurrence of cardiac arrhythmias during the recovery period. Results: Ventricular premature beats were documented in 18 patients (38%). Ventricular tachycardia, ventricular fibrillation and atrial fibrillation were not documented throughout the observed group. Conclusion: In the observed group of forty eight patients with type II and type III Brugada ECG patterns, an increased incidence of cardiac arrhythmias was not documented during the recovery period at the time of exercise stress testing. In this group of patients ventricular premature beats occurred at the similar rate to that documented in general population.