Diagnostic utility of bipolar precordial leads during ajmaline testing for suspected Brugada syndrome. 
Leads V(1) and V(2) recorded from the standard position (fourth intercostal space) have insufficient sensitivity to detect the diagnostic type 1 Brugada ECG pattern.  The purpose of this study was to compare the sensitivity of bipolar leads with a positive pole at V(2) and a negative pole at V(4) or V(5) with that of the standard unipolar lead V(2) for detection of the type 1 Brugada pattern.  We analyzed digital 15-lead ECGs (12 standard leads plus leads V(1) to V(3) recorded from the third intercostal space [V(1h) to V(3h)]) 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 V(2) (positive pole) and V(4) or V(5) (leads V(2-4), V(2-5)) were derived by subtracting leads V(4) and V(5) from V(2).  All ECGs were examined for the presence of type 1 Brugada pattern.  During 21 (16.4%) positive ajmaline tests, type 1 pattern was observed in lead V(2h) during 20 tests (95.2%) and in V(2) during 10 tests (47.6%).  Type 1 pattern appeared in lead V(2-4) or V(2-5) in all tests when it was present in V(2) and in seven tests during which it was observed in lead V(2h) but not V(2) (17 tests [81%]).  Type 1-like pattern was observed in lead V(2-4) or V(2-5) during two nonpositive tests (1.9%) and in one healthy subject (0.4%).  Bipolar leads V(2-4) and V(2-5) are more sensitive than lead V(2) for detection of the type 1 Brugada pattern.