Type 2 and type 3 ECG patterns (panels 1 and 4, respectively) and different methods for measurement. The alpha and beta angles²⁷ are illustrated in panels 1 and 2, distinguishing between a non-diagnostic type 2 Brugada pattern (panel 1) and benign incomplete RBBB (panel 2). Both angles are greater in patients with likely BrS than in incomplete RBBB and are therefore more likely to be associated with the type 1 Brugada pattern following SCB testing (cut-offs for a positive result: α > 50°, sensitivity 71% and specificity 79%; β > 58°, sensitivity 79% and specificity 83%). The base of the triangle method provides an alternative assessment of the β angle. In panel 3, the base of triangle (C) at 5 mm (0.5 mV—A) from the peak of the R wave is associated with induction of the type 1 Brugada pattern [cut-off C >140 ms (>3.5 mm) sensitivity 81% and specificity 82%].²⁸ Similarly, the duration of the base at the isoelectric line (G) illustrated in panel 4 associates with the type 1 Brugada pattern [cut-off G >60 ms (>1.5 mm) 95% sensitivity and 78% specificity] as does the triangle base (G):height (E) ratio.²⁹ BrS, Brugada syndrome; RBBB, right bundle branch block; SCB, sodium channel blocker.