Single Oral Flecainide Dose to Unmask Type 1 Brugada Syndrome Electrocardiographic Pattern

Background Brugada syndrome (BrS) includes a group of patients with a typical pattern of ST segment elevation in right precordial leads who are at risk for sudden cardiac death. The electrocardiogram pattern may be intermittent and unmasked by sodium channel blockers. The main objective of this study is to describe a serie of consecutive patients in whom oral administration of flecainide was used to unmask BrS type I electrocardiographic pattern. Methods We prospectively studied 14 symptomatic (palpitations/syncope) patients referred to our laboratory presenting a suggestive but not diagnostic Brugada ECG or family history of sudden death. Single oral dose of flecainide 400 mg was administered. Resting 12-lead ECG with upper and standard right precordial leads were performed after flecainide administration at 15, 30, 60 and 90 min and hourly until ECG became normal. Results Median age was 37.5 years (range= 22-50). None of them had structural heart disease. In 7 patients (50%) the typical coved-type ECG pattern of BrS was unmasked. PR interval, QRS duration and QTc median difference after-before test was 20 msec (min-max= -17-+57), 21 ms (min-max= 0 to +59) and 20 ms (min-max= -11-+77), respectively. There were no episodes of AV block, atrial or ventricular tachyarrhythmia. Conclusions In our experience we found that oral administration of flecainide in a single dose of 400 mg is useful to unmask type 1 Brugada electrocardiographic pattern.