Utility of electrophysiological studies to predict arrhythmic events

Table 1 Baseline characteristics

Characteristic	All study participants n = 265	Participants without primary endpoint event1n = 216	Participants with primary endpoint event1n = 49	P value2
Age, mean ± SD, yr	57.4 ± 10.7	57.5 ± 10.6	57.2 ± 11.3	0.848
Male sex	230 (86.8%)	185 (85.6%)	45 (91.8%)	0.350
Cardiovascular risk factors
Hypertension	152 (57.4%)	124 (57.4%)	28 (57.1%)	0.973
Dyslipidemia	161 (60.8%)	131 (60.6%)	30 (61.2%)	0.941
Diabetes mellitus	60 (22.6%)	49 (22.7%)	11 (22.4%)	0.972
Smoking3	154 (58.1%)	121 (56.0%)	33 (67.3%)	0.147
Family history of CAD	81 (30.6%)	65 (30.1%)	16 (32.7%)	0.725
Cardiac disease
CAD	152 (57.4%)	120 (55.6%)	32 (65.3%)	0.213
DCM	58 (21.9%)	45 (20.8%)	13 (26.5%)	0.384
HCMObstructiveNon-obstructive	1 (0.4%)3 (1.1%)	1 (0.5%)2 (0.9%)	0 (0.0%)1 (2.0%)	1.0000.460
Brugada syndrome	2 (0.8%)	2 (0.9%)	0 (0.0%)	1.000
Long QT	3 (1.1%)	3 (1.4%)	0 (0.0%)	1.000
Other cardiac disease	30 (11.3%)	26 (12.0%)	4 (8.2%)	0.618
Echocardiography
LVEF, mean ± SD	41.1% ± 15.9%	42.8% ± 16.2%	33.6% ± 11.7%	< 0.001
LVEF < 35%	106 (40.0%)	79 (36.6%)	27 (55.1%)	0.017
EPS
Induction of sustained VT	125 (47.2%)	91 (42.1%)	34 (69.4%)	0.001
Induction of non-sustained VT	60 (22.6%)	53 (24.5%)	7 (14.3%)	0.122
No VT induction	80 (30.2%)	72 (33.3%)	8 (16.3%)	0.019

¹Event of primary endpoint (sudden cardiac death, ICD shock or ATP);

²P value for the comparison of participants without vs with endpoint event;

³Current or former smoker. CAD: Coronary artery disease; DCM: Dilated cardiomyopathy; EPS: Electrophysiological study; HCM: Hypertrophic cardiomyopathy; LVEF: Left ventricular ejection fraction; SD: Standard deviation; VT: Ventricular tachycardia.

Table 2 Diagnostic accuracy of the electrophysiological study and the left ventricular ejection fraction for the primary and secondary endpoint

Predictor variable	Sensitivity	Specificity	PPV	NPV	AUROC (95%CI)
Primary endpoint
Sustained VT during EPS
All study participants (n = 265)	69.4%	57.9%	27.2%	89.3%	0.636 (0.563-0.709)
Subgroup of study participants with LVEF < 35% (n = 106)	66.7%	48.1%	30.5%	80.9%	0.574 (0.468-0.680)
Subgroup of study participants with LVEF ≥ 35% (n = 159)	72.7%	63.5%	24.2%	93.5%	0.681 (0.578-0.785)
LVEF < 35%	55.1%	63.4%	25.5%	86.1%	0.593 (0.515-0.670)
Secondary endpoint
Sustained VT during EPS
All study participants (n = 265)	66.7%	55.6%	17.6%	92.1%	0.611 (0.524-0.699)
Subgroup of study participants with LVEF < 35% (n = 106)	61.1%	45.5%	18.6%	85.1%	0.533 (0.406-0.660)
Subgroup of study participants with LVEF ≥ 35% (n = 159)	73.3%	61.8%	16.7%	95.7%	0.676 (0.553-0.798)
LVEF < 35%	54.5%	62.1%	17.0%	90.6%	0.583 (0.491-0.675)

AUROC: Area under the receiver operating characteristic curve; EPS: Electrophysiological study; NPV: Negative predictive value; PPV: Positive predictive value; VT: Ventricular tachycardia; LVEF: Left ventricular ejection fraction.