Microvolt T-wave alternans as a predictor of mortality and severe arrhythmias in patients with left-ventricular dysfunction: a systematic review and meta-analysis

Table 2 Test characteristics of microvolt T-wave alternans as a predictor of mortality or severe arrhythmias

		Patients with Endpoint (n/N)			Non-negative vs Negative MTWA†
Study	Endpoint*	Positive MTWA	Negative MTWA	Indeterminate MTWA	Sensitivity	Specificity	PPV	NPV
Chow 2006 [18]	ACM	78/514^††	21/254	NR	87.6	34.8	15.2	91.7
	AD	33/514^††	9/254	NR	78.6	33.7	6.4	96.5
Bloomfield 2006 [6]	ACM/SA/ICDS	47/360^††	4/189	NR	92.2	37.1	13.1	97.9
Grimm 2003 [19]	CD/SA	18/137	7/72	13/54	82.6	28.9	16.2	90.3
Klingenheben 2000 [22]	CD/VT/VF	11/52	0/33	2/22	100	35.1	17.6	100
Ikeda 2000 [20]	SA	14/50	1/52	NR	NE	NE	NE	98.1
Kitamura 2002 [21]	CD	3/46	0/37	NR	NE	NE	NE	100
	SA	8/46	1/37	NR	NE	NE	NE	97.2
	CD/SA	11/46	1/37	NR	NE	NE	NE	97.2
Sarzi Braga 2004 [24]	CD	7/23	0/13	0/8	100	35.1	22.6	100
Sakabe 2001 [23]	SA	13/24	0/6	NR	NE	NE	NE	100

Abbreviations: ACM: all-cause mortality; AD: arrhythmic death; CA: cardiac arrest; CD: cardiac death; ICDS: implantable cardioverter defibrillator shock; NPV: negative predictive value; NE: not estimable; NR: not reported; PPV: positive predictive value; SA: severe arrhythmias (ventricular fibrillation or ventricular tachycardia); VF: ventricular fibrillation; VT: ventricular tachycardia;
* The inclusion of more than one clinical endpoint per row represents the use of a composite endpoint.
† Test characteristics are for non-negative (i.e., positive and indeterminate) vs negative MTWA. Valid estimates of the sensitivity, specificity, and PPV can only be obtained when indeterminate tests are included. Consequently, test characteristics for Grimm [19], Klingenheben [22], and Sarzi Braga [24] were recalculated using non-negative or negative MTWA. Sensitivity, specificity, and PPV for studies that excluded indeterminate tests were not estimable (NE).
†† The studies conducted by Chow [18] and Bloomfield [6] categorized participants as non-negative or negative MTWA. Consequently, these data represent patients with endpoints who had a non-negative test.

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