Prevalence of type 1 brugada electrocardiographic pattern evaluated by twelve-lead twenty-four-hour holter monitoring.

Patients with drug-induced type 1 Brugada electrocardiograms (BrECGs) are considered to have good prognosis. Spontaneous type 1 is, instead, considered a risk factor; however, it is probably underestimated because of the BrECG fluctuations. The aim of this study was to analyze, in a large population of patients with Br, the real prevalence of type 1 BrECG using 12-lead 24-hour Holter monitoring (12L-Holter) and its correlation with the time of the day. We recorded 303 12L-Holter in 251 patients. Seventy-five (30%) patients exhibited spontaneous type 1 BrECG at 12-lead ECG (group 1) and 176 (70%) had only drug-induced type 1 (group 2). Type 1 BrECG was defined as "persistent" (>85% of the recording), "intermittent" (<85%), or "absent." In group 1, 12% showed persistent type 1 at 12L-Holter, 57% intermittent type 1%, and 31% never had type 1; in group 2, none had persistent type 1, 20% had intermittent type 1%, and 80% never showed type 1. To evaluate the circadian fluctuations of BrECG, 4 periods in the day were considered. Type 1 BrECG was more frequent between 12-noon and 6 p.m. (52%, p <0.001). In conclusion, in patients with drug-induced type 1, spontaneous type 1 BrECG can be detected more frequently with 12L-Holter than with conventional follow-up with periodic ECGs and this has important implications in the risk stratification. 12L-Holter recording might avoid 20% of the pharmacological challenges with sodium channel blockers, which are not without risks, and should thus be considered as the first screening test, particularly in children or in presence of borderline diagnostic basal ECG.