Diagnostic utility of bipolar precordial leads during ajmaline testing for suspected Brugada syndrome

BackgroundLeads V1 and V2 recorded from the standard position (fourth intercostal space) have insufficient sensitivity to detect the diagnostic type 1 Brugada ECG pattern.ObjectiveThe purpose of this study was to compare the sensitivity of bipolar leads with a positive pole at V2 and a negative pole at V4 or V5 with that of the standard unipolar lead V2 for detection of the type 1 Brugada pattern.MethodsWe analyzed digital 15-lead ECGs (12 standard leads plus leads V1 to V3 recorded from the third intercostal space [V1h to V3h]) acquired during diagnostic ajmaline testing in 128 patients (80 men, age 37 ± 15 years) with suspected Brugada syndrome and standard 12-lead ECGs recorded in 229 healthy subjects (111 men, age 33 ± 4 years). Bipolar leads between V2 (positive pole) and V4 or V5 (leads V2–4, V2–5) were derived by subtracting leads V4 and V5 from V2. All ECGs were examined for the presence of type 1 Brugada pattern.ResultsDuring 21 (16.4%) positive ajmaline tests, type 1 pattern was observed in lead V2h during 20 tests (95.2%) and in V2 during 10 tests (47.6%). Type 1 pattern appeared in lead V2–4 or V2–5 in all tests when it was present in V2 and in seven tests during which it was observed in lead V2h but not V2 (17 tests [81%]). Type 1–like pattern was observed in lead V2–4 or V2–5 during two nonpositive tests (1.9%) and in one healthy subject (0.4%).ConclusionBipolar leads V2–4 and V2–5 are more sensitive than lead V2 for detection of the type 1 Brugada pattern.