Syncope in pharmacologically unmasked Brugada syndrome: indication for an implantable defibrillator or an unresolved dilemma?

A 30-year-old Caucasian male was referred for evaluation of a 2-year history of recurrent post-exertion lightheadedness and near syncopal spells in the setting of a family history of unexplained sudden cardiac death. Cardiac evaluation demonstrated normal heart structure, but the 12-lead surface ECG was suggestive of but not diagnostic of Brugada syndrome. An exercise stress test reproduced the patient's usual symptoms during the recovery period, and was consistent with a typical vasovagal faint. The same symptoms were observed during a head-up tilt table test. However, given the family history and ECG, pharmacological testing with procainamide, isoprenaline and metoprolol, as well as programmed ventricular stimulation, were undertaken. Pharmacological provocation further supported a diagnosis of Brugada syndrome, whereas programmed ventricular stimulation was considered non-diagnostic regarding ventricular tachyarrhythmia susceptibility. Consequently, despite ECG and pharmacological findings suggestive of Brugada syndrome, there appeared to be sufficient evidence to believe that this patient's symptoms were the result of neurally mediated syncope and not due to ventricular tachyarrhythmias. The patient was treated with midodrine, and has remained symptom-free for 16 months. Thus, given the frequency with which vasovagal syncope occurs in young patients, its occurrence is not unexpected in individuals with concomitant diagnoses such as Brugada syndrome. In as much as current recommendations favour implantable defibrillators in symptomatic Brugada syndrome, the identification of other causes of syncope in such patients poses an uncomfortable, and currently unsettled dilemma.