Table 2. Derivation and validation cohorts.

Characteristic	Derivation cohort (n=2242)	Validation cohort (n=1113)
Age (years)	61.7±11.5	61.7±11.7
Male gender (n)	1747 (78%)	885 (80%)
Coronary artery disease (n)	1687 (75%)	845 (76%)
Left ventricle ejection fraction (%)	41.6±16.1	41.3±16.5
β-blocker use (n)	1067 (48%)	531 (48%)
Microvolt T-wave alternans result (n)
Positive	651 (29%)	345 (31%)
Negative	1197 (53%)	593 (53%)
Indeterminate	394 (18%)	175 (16%)
Duration of follow-up (months)	20.4±6.0	20.4±6.3

Data are presented as mean±standard deviation or n (%).