Body surface potential mapping in patients with Brugada syndrome: right precordial ST segment variations and reverse changes in left precordial leads.

OBJECTIVE The aim of this study was to perform quantitative signal analysis of high-resolution body surface potential mapping (BSPM) recordings to assess its usefulness for the electrocardiographic characterization of patients with Brugada syndrome. The diagnostic value of the QRS integral and of the gradient of the ST segment have not been elucidated in Brugada syndrome. METHODS In 27 subjects (16 with Brugada syndrome and 11 healthy subjects), 120-lead BSPMs were recorded at baseline and after pharmacological provocation with intravenous administration of ajmaline (1 mg/kg). The recordings were analyzed for two regions outside the positions of the standard ECG leads: the right precordial leads (RPL) on the second and third intercostal space (high RPL) and the left precordial leads (LPL) between the fifth and seventh intercostal space (low LPL). RESULTS At baseline, in high RPL regions, patients with Brugada syndrome showed more positive QRS integrals (-5+/-8 vs. -16+/-8 mV ms) and a steeper negative ST segment gradient (-0.62+/-0.41 vs. -0.29+/-0.40 mV/s) compared to healthy subjects, P<0.001. In contrast, in low LPL regions, reduced QRS integrals and positive ST segment gradients were observed. These ECG signs were even more pronounced after intravenous ajmaline and showed a better discrimination for patients with Brugada syndrome than differences in RPL or LPL during baseline, respectively. CONCLUSIONS In the left precordial leads, patients with Brugada syndrome showed ECG changes which were reversed in relation to the ECG changes observed in right precordial leads. BSPM measurement is a useful tool to improve the understanding of the electrocardiographic changes in the Brugada syndrome.