Table 2:

Trials of Pacemakers for NCS

Study	Type of Study	Inclusion Criteria	Number of Patients (Intervention/Control)	Intervention/Control	Mean Follow-up	Syncope Recurrence (Intervention/Control)
Connolly et al. 199933	Nonblinded RCT	≥ six episodes of syncope plus HUT with relative bradycardia	54 (27/27)	DDD with rate-drop response/standard treatment	1 year	22%/70% (p < 0.0001)
Sutton et al. 200034	Nonblinded RCT	≥ three episodes of syncope in two years; VASIS IIa or IIb on HUT	42 (19/23)	DDI with hysteresis/no therapy	3.7 years	5%/61% (p = 0.0006)
Ammirati et al. 200135	Nonblinded RCT	≥ three episodes of syncope in two years plus HUT with relative bradycardia	93 (46/47)	DDD with rate-drop response/atenolol	520 days	4.3%/25.5% (p = 0.004)
Connolly et al. 200336	Double-blinded RCT	≥ six total episodes of syncope or ≥ three episodes in two years plus HUT with heart rate × blood pressure < 6,000 bpm × mmHg	94 (42/52)	DDD with rate-drop response/sensing only (ODO)	6 months	33%/42% (p = 0.14)
Raviele et al. 200437	Double-blinded RCT	≥ six episodes of syncope plus HUT with asystolic or mixed response	29 (16/13)	DDD with rate-drop response/no pacing (OOO)	715 days	50%/33% (p = not reported)
Brignole et al. 200639	Observational	≥ three episodes of syncope in two years	392	Implantable loop recorder- based specific therapy (pacemaker, anti-tachycardia therapy)/no therapy	9 months	11%/35% (p = 0.002)
Brignole et al. 201440	Double-blinded RCT	≥ three episodes of syncope in two years; ILR-documented asystolic response	77 (38/39)	DDD with rate-drop response/sensing only (ODO)	2 years	25%/57% (p = 0.039)
Flammang et al. 201241	SIngle-blinded RCT	Isolated or recurrent syncope; > 10-second pause on ATP test	80 (39/41)	DDD/backup pacing (AAI)	16 months	66%/21% (p = not reported)

NCS: neurocardiogenic syncope; RCT: randomized controlled trial; HUT: head-up tilt test; ILR: implantable loop recorder; ATP: adenosine triphosphate.