Fever outperforms flecainide test in the unmasking of type 1 Brugada syndrome electrocardiogram

A thirty-year-old male patient with previous abrupt syncopal episode and a family history of sudden cardiac death was seen for a type 2 Brugada pattern. Risk stratification was performed through flecainide test and programmed electrical stimulation, which were negative. Two weeks later, a new was electrocardiogram (ECG) performed during a febrile syndrome, with precordial leads at third intercostal space, unmasked unequivocal type 1 Brugada pattern. Drug testing with flecainide or ajmaline is recommended in symptomatic patients with non-type 1 Brugada pattern, as symptomatic patients with drug-induced type 1 ECG carry a worse prognosis than their counterparts with non-inducible type I pattern. Although a negative test does not exclude the presence of Brugada syndrome (BS) and several studies have demonstrated the appropriateness of the flecainide/ajmaline challenges to unmask electrocardiographic patterns of BS, some authors have found disparate responses of BS patients to these two drugs. A previous study reported a failure of flecainide in 7 of 22 cases (32%) who had previously had a positive response to ajmaline testing, explained as resulting from greater inhibition of Ito by flecainide rendering it less effective. In our patient, fever outperformed the flecainide test for unmasking type I BS ECG. Accelerated inactivation of sodium channels under conditions of elevated temperature might be sufficient to obliterate phase-1 depolarization reserve and shift balance of currents in favour of premature repolarization, revealing BS phenotype. Furthermore, it is not known whether currents other than (INa) may present temperature-dependent changes underlying the ECG phenotype. This case demonstrates how important it is for symptomatic patients with non-type 1 Brugada pattern to perform an ECG in case of fever, irrespective of the result of the flecainide drug challenge. Conflict of interest: R.P. holds a research grant from Medtronic and a training grant from Boston Scientific. The full-length version of this report can be viewed at: http://www.escardio.org/communities/EHRA/publications/ep-case-reports/Documents/flecainide-test-fever-brugada-syndrome.pdf