Table 1.

Baseline Demographics of Cohort

Sex (male/female)	32/40
Age at diagnosis (yr)	11±10
Age at LCSD (yr)	14±10
Baseline QTc (ms)	505±56
ICD pre-LCSD, no. (%)	18 (28%)
B-blocker, no. (%)	67 (93%)
Genotype positive, no. (%)	67 (93%)
LQT1	36 (50%)
LQT2	17 (24%)
LQT3	5 (7%)
JLNS	6 (8%)
Other	3 (4%)
Genotype negative/Phenotype positive	4 (6%)
Symptom at diagnosis, no. (%)	38 (53%)
None	34 (47%)
Syncope	26 (36%)
Cardiac arrest	7 (10%)
Fetal arrhythmia	5 (7%)
Indication for LCSD, no. (%)
Beta-blocker intolerance	28 (39%)
Additional protection	19 (26%)
Breakthrough cardiac events	15 (21%)
Severe LQTS/high-risk	10 (14%)