Low‐Voltage Type 1 ECG Is Associated With Fatal Ventricular Tachyarrhythmia in Brugada Syndrome

Figures

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  Figure 1. Position of 9 right precordial ECG leads analyzed in this study. In this study, V1 to V3 leads positioned in the standard and upper 1 and 2 intercostal spaces (+1ICS and +2ICS, respectively) were recorded for evaluation of the number and amplitude of type 1 ECG.

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  Figure 2. Measurements of ECG parameters in leads showing type 1. Among the 9 right precordial leads, the amplitudes of late R′, S, and late R′ plus S were evaluated in each ECG lead showing type 1.

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  Figure 3. Distribution of the number of ECG leads showing type 1 in 3 groups. The number of ECG leads showing type 1 among the 9 right precordial leads did not differ among the 3 groups (P=not significant). The distribution points overlapped widely among the 3 groups. Numerical values show the mean±SD. AS indicates patient without any symptoms; SY, patient with a previous syncope episode; VF, patient with documented ventricular fibrillation.

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  Figure 4. Box‐plot diagram showing the amplitude of type 1 ECG in each group. A, Averaged S‐wave amplitude of type 1 ECG. B, Averaged late R′ plus S‐wave amplitude of type 1 ECG. C, Minimum S‐wave amplitude of type 1 ECG. D, Minimum late R′ plus S‐wave amplitude of type 1 ECG. AS indicates patient without any symptoms; SY, patient with a previous syncope episode; VF, patient with documented ventricular fibrillation.

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  Figure 5. Representative cases. Representative cases of ECGs, including the 9 right precordial leads (green frame) and evaluated data in this study. Red asterisks indicate type 1 ECG. Numerical values on the ECG show the amplitude of later R′ (top panels) and S (bottom panels) in each ECG showing type 1. A, A 31‐year‐old male patient without any symptoms (group AS). This patient was free from all symptoms during follow‐up. Minimum late R′, minimum S, and minimum late R′ plus S were recorded in lead V1. B, A 66‐year‐old male patient with a previous syncope episode (group SY). This patient was free from all symptoms during follow‐up. Minimum late R′ was recorded in lead V3 with upper 2 intercostal spaces (+2ICS), and minimum S and minimum late R′ plus S were recorded in lead V1 with upper 1 intercostal space (+1ICS). C, A 52‐year‐old male group AS patient. In this patient, a ventricular fibrillation episode was observed during follow‐up. Minimum late R′ was recorded in lead V1+2 ICS, and minimum S and minimum late R′ plus S were recorded in lead V3+2 ICS. D, A 51‐year‐old male group SY patient. In this patient, a ventricular fibrillation episode was observed during follow‐up. Minimum late R′…

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  Figure 6. Kaplan‐Meier analysis of freedom from ventricular fibrillation (VF) event. Patients with the minimum late R′ plus S amplitude of type 1 ECG at or lower than the median value (0.97 mV) had a higher incidence of VF than others (log‐rank test, P<0.01).

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  Figure 7. Receiver‐operating characteristic (ROC) curve and area under the curve (AUC). ROC curve comparing the sensitivity and specificity of the minimum late R′ plus S amplitude and future ventricular fibrillation (VF) event. ROC curve analysis for the amplitude of the late R′+ S wave in type 1 ECG revealed that the optimized cutoff point in the prediction of VF event during follow‐up was 0.78 mV.

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  Figure 8. Kaplan‐Meier analysis of freedom from ventricular fibrillation (VF) event. Kaplan‐Meier analysis revealed that the patients with minimum late R′ plus S amplitude of ≤0.8 mV had a significantly worse prognosis.