Background : Early repolarization pattern (ERP) is associated with long-term cardiovascular death. However, the incidence of early repolarization syndrome ( ERS) has never been studied in a general population-based cohort study. Purpose : To determine the prevalence and long-term outcome of ERP as well as the incidence of ERS in a general population-based cohort study. Methods : Participants from the electricity generating authority of Thailand (EGAT) study during 1997 to 2015 were included. The outcomes included cardiovascular death,deaths due to acute myocardial infarction, SCD, and all-cause mortality. A Cox- proportional hazard model was used to determine the association between ERP and the outcomes. Results: 2,689 participants with completed ECGs and risk factor profiles were included for the analysis. Mean follow up duration was 11.2±6.7 years. There were 444 participants with baseline ERP. There were 566 deaths during the follow-ups; of these, 21 were SCD including 6 ERS. The prevalence and incidence of ERS in our study was 0.22% and 0.20 per 1000 person-year. Overall, ERP was not associated with an increased risk of all-cause mortality (hazard ratio [HR]=1.04; 95% confidence interval [CI]:0.81 to 1.34; p =0.75). However, ERP was associated with an increased risk of all-cause mortality in the population ≤55 years old (HR=2.36; 95% CI:1.47-3.77; p <0.01). Conclusion : The prevalence of ERP in the Thai population was higher than the prevalence in other countries in Asia. Our study supports previous studies that ERP is associated with a long-term increased risk of all-cause mortality in the young-middle age population.

Introduction: Brugada syndrome is associated with ventricular arrhythmia leading to sudden cardiac death. Risk stratification is challenging, as major arrhythmic events (MAE) are rare. We assessed the utility of drug challenge testing in Brugada syndrome by a systematic review and meta-analysis. Methods and results: We comprehensively searched the databases of MEDLINE and EMBASE from inception to May 2019. Included studies compared the incidence of MAE between spontaneous and drug challenge induced Type-1. Data were combined using the random-effects, generic inverse variance method, to calculate pooled incidence and odds ratio (OR). Mixed-effects Poisson regression was used to calculated incidence rate ratio (IRR). Eighteen studies from 2006 to 2018 were included (4,099 patients, mean follow-up 4.5 years). Pooled annual incidences of MAE in spontaneous, drug challenge induced (regardless of symptoms), asymptomatic drug challenge induced, and symptomatic drug challenge induced Type-1 were 23.8 (95% confidence interval [CI]: 19.8-27.8), 6.5 (95% CI: 3.9-9.1), 2.1 (95% CI: -0.3-4.4), and 19.6 (95% CI: 9.9-29.3) per 1,000 person-years respectively. The incidence of MAE between symptomatic drug challenge induced and asymptomatic spontaneous Type-1 was not statistically different (IRR=1.0, 95%CI: 0.6-1.7). The presence of ventricular tachyarrhythmia during drug challenge testing was a predictor of MAE (OR=3.73, 95% CI: 1.77-7.86, p=0.001). Conclusions: The incidence of MAE in drug challenge induced Type-1 in asymptomatic patients is low. The incidence of MAE between symptomatic drug challenge induced and asymptomatic spontaneous Type-1 was similar. Ventricular tachyarrhythmia during drug challenge testing could be a useful risk marker for MAE in Brugada syndrome.