Introduction Brugada syndrome is an established cause of sudden arrhythmic death syndrome (SADS). The use of higher (2nd-intercostal space) intercostal V1 and V2 leads has been associated with increased surface electrocardiogram (ECG) sensitivity in the detection of the Brugada phenotype, either on the baseline ECG or following provocation using sodium ion channel blocking agents, without compromising specificity. Despite the potential implications, there is a paucity of data relating to the efficacy of this simple methodology in the diagnostic yield of Brugada syndrome in victims of ventricular fibrillation (VF) or 1st-degree relatives of SADS victims.
Methods We identified 34 families diagnosed with Brugada syndrome based on the presence of a type-1 ECG in ¡Ý1 family members in the context of an unexplained VF arrest or a SADS death in a 1st-degree relative. The 12-lead ECGs of 139 individuals, who underwent comprehensive cardiac investigations including an Ajmaline provocation test, when appropriate, were reviewed. Electrocardiograms were performed with leads V1 and V2 placed in both the conventional 4th and the higher 2nd intercostal space. Family members not genetically related to the individuals diagnosed with Brugada syndrome were used as controls.
Results Fifty-two of the 139 family members (37%) were diagnosed with Brugada syndrome. Only 6 (12%) individuals exhibited a diagnostic baseline ECG, while the great majority required an Ajmaline provocation test to unmask the Brugada phenotype. Of the 111 individuals who received Ajmaline, 22 (20%) developed the Brugada phenotype in the conventional ECG. The diagnostic Brugada phenotype was observed in 48 (43%) individuals by raising V1 and V2 leads at the 2nd-intercostal space (p<0.001). None of the controls exhibited the Brugada phenotype in either the conventional or higher intercostal leads.
Only 18 (53%) of the families were diagnosed on the basis of the standard ECG lead whereas all 34 (100%) families had at least one member with a positive type-1 ECG in the higher intercostal leads (p<0.001).
Conclusion Utilising higher intercostal leads for the detection of Brugada phenotype increases the diagnostic yield when screening families of SADS victims. This is primarily due to increased sensitivity of the Ajmaline provocation test. In our cohort almost 50% of the families and the majority (56%) of 1st-degree family relatives harbouring the Brugada gene would have remained undetected based on the standard 12-lead ECG alone.
- Brugada syndrome
- Sudden arrhythmic death syndrome