The Utility of Sodium Channel Provocation in Unexplained Cardiac Arrest Survivors and Electrocardiographic Predictors of Ventricular Fibrillation Recurrence.

BACKGROUND: The implications of a drug-induced type 1 Brugada ECG pattern following sodium channel blocker provocation (SCBP) are not fully understood. METHODS: Baseline clinical and ECG data were obtained from consecutive unexplained cardiac arrest survivors undergoing SCBP at 3 centers. A further 15 SCBP positive (SCBP+) unexplained cardiac arrest survivors were recruited from 3 additional centers to explore ventricular fibrillation recurrence. RESULTS: A total of 121 consecutive unexplained cardiac arrest survivors underwent SCBP. The yield of the drug-induced type 1 Brugada ECG pattern was 17%. A baseline type 2/3 Brugada pattern (T2/3BP) (adjusted odds ratio, 19.36 [2.74-136.61]; P=0.003) and PR interval (odds ratio, 1.03 [1.01-1.05] per ms; P=0.017) were independent predictors of SCBP+ response. A pathogenic SCN5A variant was identified in 36% of the SCBP+ group versus 0% in the SCBP- group (P<0.001). Amongst SCBP+ patients, a spontaneous type 1 Brugada pattern was identified in 19% during follow up and in 24% a type 1 Brugada pattern was identified in a relative. Prior syncope (adjusted hazard ratio, 3.83 [1.36-10.78]; P=0.011) and the presence of global early repolarization (hazard ratio, 7.91 [3.22-19.44]; P<0.001) were independent predictors of 5-year ventricular fibrillation recurrence. There was a nonsignificant trend toward greater 5-year ventricular fibrillation recurrence in the SCBP- group (23/95 [24%] versus 3/34 [9%]; P=0.055). CONCLUSIONS: The yield of the drug-induced type 1 Brugada ECG pattern in consecutive unexplained cardiac arrest survivors undergoing SCBP is 17%. A baseline T2/3BP and PR interval were independent predictors of the drug-induced type 1 Brugada ECG pattern. Greater heritability of BrS phenotype in this group was evidenced by a greater prevalence of pathogenic SCN5A variants and relatives with a type 1 Brugada pattern. A history of prior syncope and the presence of global early repolarization were independent predictors of ventricular fibrillation recurrence.

Sudden cardiac death caused by myocarditis in persons aged 1-49 years: a nationwide study of 14 294 deaths in Denmark.

Myocarditis is associated with an increased risk of sudden cardiac death (SCD) in the young. However, information on nationwide burden of SCD caused by myocarditis (SCD-myocarditis) is sparse. For this study all deaths among persons in Denmark aged 1-35 years in 2000-2009 and 36-49 years in 2007-2009 (27.1 million person-years) were included. Autopsy reports, death certificates, discharge summaries, and nationwide registries were used to identify all cases of SCD-myocarditis. In the 10-year study period, there were 14 294 deaths, of which we identified 1 363 (10%) SCD. Among autopsied SCD (n = 753, 55%), cause of death was myocarditis in 42 (6%) cases corresponding to an SCD-myocarditis incidence of 0.16 (95%CI: 0.11-0.21) per 100 000 person-years. Males had significantly higher incidence rates of SCD-myocarditis compared to females with an incidence rate ratio of 2.2 (95%CI: 1.1-4.1). Myocarditis was not registered as cause of death in any of the non-autopsied SCD (n = 610, 45%). In conclusion, after nationwide unselected inclusion of 14 294 deaths, we found that 6% of all autopsied SCD was caused by myocarditis. No cases of SCD-myocarditis were reported in the non-autopsied SCD, which could reflect underdiagnosing of myocarditis in non-autopsied SCD. Furthermore, our data suggest a female protection towards SCD-myocarditis.