TABLE 2.

Model predicting ACA, SCD, or appropriate ICD shock after enrollment in 1,509 LQTS patients with QTc ≥ 470 ms (No. of events = 77, 30 SCD, 14 ACA, and 33 shock).

Variables in the model	β	HR	95% CI		P
QTc, per 10 ms increase	0.08	1.09	1.05	1.13	<0.001
Age at enrollment (Ref: 0– < 10 years)
10– < 20 years	-0.37	0.69	0.38	1.25	0.221
20–50 years	-1.16	0.31	0.16	0.62	0.001
Time-dependent syncope (Ref: No syncope)
Syncope while off BB	1.14	3.12	1.59	6.11	0.001
Syncope while on BB	1.77	5.87	2.89	11.90	<001
Time-dependent beta-blocker (yes vs. no)	-0.58	0.56	0.34	0.93	0.024
Sex by time-dependent age (female vs. male)
<13 years	-1.01	0.36	0.11	1.22	0.102
≥13 years	0.37	1.45	0.84	2.50	0.185
C statistic	0.784 (0.740–0.827)

Robust sandwich estimates of standard errors were used. P-value for interaction between time-dependent age and sex: 0.038.