3.4 Meta-analysis results
Pooled annual incidences of MAE in spontaneous and drug challenge induced Type-1 Brugada pattern were 23.8 (95% CI: 19.8-27.8) (Figure 2) and 6.5 (95% CI: 3.9-9.1) per 1,000 person-years (Figure 3) respectively. Spontaneous Type-1 Brugada pattern was associated with a higher risk of MAE (OR=3.05, 95%CI: 2.08-4.46, p<0.001, I2=23.8%) than drug challenge induced Type-1 Brugada pattern (Figure 4).
We performed subgroup analysis of symptomatic (with history of syncope or documented SCD, sudden cardiac arrest, VF, sustained ventricular tachycardia) and asymptomatic (without history of syncope or documented SCD, sudden cardiac arrest, VF, sustained ventricular tachycardia) drug challenge induced Type-1 Brugada pattern subjects. In asymptomatic individuals with drug challenge induced Type-1 Brugada pattern, pooled annual incidences of MAE was 2.1 (95% CI: -0.3-4.4) per 1,000. In symptomatic individuals with drug challenge induced Type-1 Brugada pattern, pooled annual incidences of MAE was 19.6 (95% CI: 9.9-29.3) per 1,000. Thus, the combination of symptoms and drug challenge induced Type-1 Brugada pattern was associated with a higher risk of MAE (IRR=9.7, 95%CI: 3.6-25.9, p<0.001) than drug challenge induced Type-1 Brugada pattern but no history of symptoms. Drug challenge induced Type-1 Brugada pattern in symptomatic patients has a similar incidence of MAE when compared to asymptomatic spontaneous Type-1 Brugada pattern (IRR=1.0, 95%CI: 0.6-1.7, p=0.861).
The presence of ventricular tachyarrhythmia during drug challenge testing was associated with four-fold increased risk of MAE in drug challenge induced BrS patients (pooled OR=3.73, 95% CI: 1.77-7.86, p=0.001, I2=0.0%) (Figure 5) and increased to 13-fold in the subgroup of symptomatic patients (pooled OR=12.9, 95% CI: 3.8-43.2, p<0.001, I2=0.0%). In asymptomatic drug challenge induced BrS patients, ventricular tachyarrhythmia during drug challenge testing increased risk of MAE but non-significant (OR=2.78, 95% CI: 0.07-103.83) (data only available from one study)(16).