Electrocardiographic predictors of Brugada type response during Na channel blockade challenge

To identify ECG predictors of Brugada type response during Na channel blockade challenge.

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 (−2V ₁ and −2V ₂ ). 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.

Ajmaline challenge was positive in 48 (47%) of the 103 cases. Baseline J wave elevation was greater in −2V ₁ (0.077±0.078 mV vs. 0.038±0.046 mV, P =0.003) and −2V ₂ (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 V ₁ , V ₂ and V ₃ . Logistic regression showed that J wave elevation in −2V ₂ and decreased T wave amplitude in V ₃ at baseline were independent predictors of a positive response. Baseline J wave elevation >0.16 mV in −2V ₂ had a specificity of 100%, a sensitivity of 40%, a positive predictive value of 100% and a negative predictive value of 28%.

J wave elevation >0.16 mV in −2V ₂ was the strongest predictor of a Brugada type response to Na channel blockade challenge when Brugada syndrome was suspected on a baseline ECG.