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).