Table 1. Baseline characteristics stratified by study of origin.

	Bloomfield et al. 21 n=472	Klingenheben et al. 26 n=107	ALPHA 25 n=415	Ikeda et al. 23 n=834	Ikeda et al. 24 n=1041	Chan et al. 22 n=486
Age (years)	55.3 ± 12.9	54.2 ± 10.1	58.6 ± 12.6	62.8 ± 10.8	63.9 ± 9.0	65.9 ± 12.5
Male gender (n)	328 (70%)	86 (80%)	349 (78%)	696 (83%)	824 (79%)	366 (75%)
Ischemic cardiomyopathy (n)	215 (46%)	67 (63%)	0	834 (100%)	1041 (100%)	375 (77%)
LV ejection fraction (%)	25.2 ± 8.5	28.2 ± 7.5	29.5 ± 7.1	50.3 ± 13.4	54.6 ± 10.4	27.8 ± 6.4
Beta blocker therapy at enrollment (n)	367 (78%)	45 (42%)	357 (80%)	232 (28%)	216 (21%)	399 (82%)
MTWA results (n)
positive	140	52	175	302	176	151
negative	163	33	151	4343	773	236
indeterminate	169	22	89	98	92	99
Duration of follow-up (months)	20.3 ± 5.9	14.6 ± 9.6	31.2 ± 16.2	24.7 ± 13.3	31.8 ± 14.0	36.9 ± 18.5
Definition of SCD endpoint	Unwitnessed deaths, witnessed instantaneous deaths nonsudden deaths due to incessant tachycardia, deaths considered to be sequelae of cardiac arrest	Sudden death, resuscitated VF or sustained VT	Unwitnessed deaths, witnessed instantaneous deaths nonsudden deaths due to incessant tachycardia, deaths considered to be sequelae of cardiac arrest	Instantaneous, unexpected death or death within one hour of symptom on-set not related to circulatory failure or resuscitated VF	Instantaneous, unexpected death or death within one hour of symptom on-set not related to circulatory failure or resuscitated VF	Unwitnessed death (if observed to be stable within 24 hrs before death), witnessed instantaneous death or sequelae of cardiac arrest
HR for SCD endpoint	Not reported	∞**	4.01*	11.4**	23.5**	Not reported

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

LV=left ventricle; MTWA=microvolt T-wave alternans; MI=myocardial infarction; SCD=sudden cardiac death; VF=ventricular fibrillation; VT=ventricular tachycardia; HR=hazard ratio.

^*for non-negative MTWA (positive and indeterminate) vs. negative MTWA

^**for positive MTWA vs. negative MTWA