Incidence and Clinical Significance of Brugada Syndrome Masked by Complete Right Bundle-Branch Block

Abstract

2568WADA T et al. Circulation JournalOfficial Journal of the Japanese Circulation Society http://www. j-circ.or.jp occasionally induces fatal ventricular tachyarrhythmia, SCB test should be avoided in patients with type 1 ECG under baseline conditions, but it is difficult to identify type 1 in BrS patients with CRBBB. The prevalence and clinical significance of the combination of CRBBB and BrS has not been well investigated. Therefore, the present study evaluated the incidence and clinical significance of BrS with CRBBB, especially BrS masked by CRBBB. Methods SubjectsA total of 326 consecutive BrS patients (mean age, 47.4±13.6 years; male, 95.4%) and 20 control subjects were enrolled in this study. All BrS patients were diagnosed as having BrS based on HRS/EHRA/APHRS expert consensus statement. 1 Type 1 ECG was documented spontaneously or was provoked by SCB test (pilsicainide, at a dose of 1 mg/kg for 5-10 min) in all BrS patients. Echocardiography was performed to exclude rugada syndrome (BrS) is characterized by ST-segment elevation at the J point in the right precordial electrocardiographic (ECG) leads and sudden cardiac death caused by polymorphic ventricular tachycardia/ventricular fibrillation (PVT/VF). This ST-segment elevation is the most important characteristic for diagnosis of BrS, 1,2 and spontaneous ST-segment elevation is reported to be a high risk for PVT/VF.

Impact of premature activation of the right ventricle with programmed stimulation in Brugada syndrome

“…Different characteristics between RBBB in healthy subjects and type‐1 BrS ECG on a vector cardiogram and body surface mapping have also been reported . Furthermore, some recent reports demonstrated that genuine CRBBB does coexist with BrS ECG and sometimes masks typical BrS ECG . We have previously reported that the prevalence of BrS patients with CRBBB was 7.7% (25 of 325 BrS patients) and typical BrS ECG was masked in 40% (10 of 25) of those patients.…”

“…They reported that type‐1 ECG converted to type‐2, type‐3, or normal ECG after elimination of delayed or fragmented potential with catheter ablation. On the other hand, complete right bundle‐branch block (CRBBB), which also causes delayed activation in the RV, can mask the typical BrS ECG and sometimes make it difficult to diagnose BrS …”

“…On the other hand, complete right bundle-branch block (CRBBB), which also causes delayed activation in the RV, can mask the typical BrS ECG and sometimes make it difficult to diagnose BrS. [12][13][14][15][16] We assumed that premature RV stimulation on electrophysiological study (EPS) allows artificial premature RV activation and can unmask the influence of delayed activation in the RV including CRBBB. The purpose of the present study was to investigate the impact of gradually premature activation in the RV on morphological change of ECG using single premature stimulation of the RV in BrS patients including those with concomitant CRBBB.…”

Masquerading bundle branch block obscuring the diagnosis of Brugada syndrome: an electrocardiographic and vectorcardiographic study

“…In our cases, the VCG obtained during masquerading BBB at peak ajmaline effect undoubtedly shows the displacement of the J‐point . The J‐point is displaced and the ST‐segment vector has a greater magnitude and is oriented forwards in the horizontal and sagittal planes; yet, the downwards slope of the ST segment observed in the ECG at 1 and 2 mm is ≥4 mm and is due to the presence of high‐degree BBB , developed within the first minutes, which modifies the characteristics of type 1 Brugada pattern as shown in Figures and .…”

Exercise stress test reveals ineligibility for subcutaneous implantable cardioverter defibrillator in patients with Brugada syndrome

“…To avoid inappropriate cardioversion of S‐ICD, morphological changes on standard 12‐lead ECG can provide initial clues to physicians to reconsider whether patients will be eligible for S‐ICD. In particular, intermittent CRBBB is sometimes observed in BrS, and could be associated with inappropriate therapy using S‐ICD …”