© 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.
Electrocardiographic predictors of Brugada type response during Na channel blockade challenge*
aAmiens-Picardie University Hospital Hôpital Sud, 80054 Amiens Cedex, France; bLariboisière University Hospital Paris, France
AIM: To identify ECG predictors of Brugada type response during Na channel blockade challenge.
METHODS: We studied prospectively 103 patients (M=76, 45±13 years) in whom ECGs were collected during ajmaline challenge. ECG recordings included the high right precordial leads (–2V1 and –2V2). A positive response was defined by a >0.2 mV J point or ST segment elevation and a down-sloping pattern of the ST segment in at least one right precordial lead.
RESULTS: Ajmaline challenge was positive in 48 (47%) of the 103 cases. Baseline J wave elevation was greater in –2V1 (0.077±0.078 mV vs. 0.038±0.046 mV, P=0.003) and –2V2 (0.149±0.103 mV vs. 0.043±0.088 mV, P<0.001) in cases with a subsequent positive response. In contrast, ST segment elevation and T wave amplitudes were reduced in V1, V2 and V3. Logistic regression showed that J wave elevation in –2V2 and decreased T wave amplitude in V3 at baseline were independent predictors of a positive response. Baseline J wave elevation >0.16 mV in –2V2 had a specificity of 100%, a sensitivity of 40%, a positive predictive value of 100% and a negative predictive value of 28%.
CONCLUSION: J wave elevation >0.16 mV in –2V2 was the strongest predictor of a Brugada type response to Na channel blockade challenge when Brugada syndrome was suspected on a baseline ECG.
Key Words: antiarrhythmia agents, genetics, electrocardiography, ion channel, Brugada syndrome
*Corresponding author. Tel.: +33 614 27 33 09; fax: +33 322 45 56 61. E-mail address: hermida.jean-sylvain{at}chu-amiens.fr (J.-S. Hermida).