|Study (Author, Year)||Study Groups||Results of Noninvasive Testing||Results of Invasive EP Study||Acute Outcome of Catheter Ablation||Clinical Outcomes of Interest||Duration of Follow-Up||Loss to Follow-Up|
|Pappone C, et al., 2003 (17)|
|Group 1: Ablation|
Group 2: No ablation
Group 3: Low-risk group followed as an observational cohort
|N/A||15/37 (41%) pts in the ablation group had inducible AVRT. In 8 additional pts, AVRT degenerated into sustained AF.|
The median number of radiofrequency applications was 9 (range, 5-22).
|Ablation was acutely successful in all pts. Complications related to EP study (2 pneumothoraxes and 1 large femoral hematoma) developed in 3 (1%) pts. An ablation-related complication (permanent right bundle-branch block) developed in 1/37 (3%) pt with an anteroseptal accessory pathway.||2/37 (5%) pts in the ablation group had an arrhythmic event, found on EP study to be due to AVNRT in both pts. Within a mean of 15 mo, 21/35 (60%) pts in the no-ablation group had an arrhythmic event, which was SVT in 15 pts, AF in 5 pts, and VF (not preceded by symptoms) in 1 pt. Among the high-risk controls (group 2), the 5-y rate of arrhythmic events was 77% vs. 7% in the ablation group. In the observational cohort, symptoms of SVT developed in 6 pts and 20 pts lost ventricular pre-excitation.||Ablation group median f/u 27 mo, range 9-60 mo. Control group median f/u 21 mo, range 8-60 mo.||None|
|Brembilla-Perrot B, et al., 2001 (18)|
|Group 1: Transesophageal stimulation||All patients had 24-h Holter and stress test performed before study entry and only those without supraventricular arrhythmia were included||The number of accessory pathways found was not reported. The ERPs of pathway(s) at baseline and during isoproterenol infusion were not reported. Shortest RR interval (<250 ms) during induced AF was present in 20/92 (22%) patients. Atrial tachyarrhythmia was induced in 27% of pts.||No ablation||3/92 (3%) pts developed symptomatic AF several years later. Of these 3 pts, 1 presented with AF and then VF 1 d after an aortic aneursymectomy. Among the 42 pts considered to have a benign form of WPW syndrome, there was no clinical event, except a death related to an accident.||—||—|
|Klein GJ, et al., 1989 (19)|
|Group 1: Invasive EP study without catheter ablation||N/A||28/29 (97%) pts had only 1 accessory pathway, and 1/29 (3%) pts had >1 accessory pathway. The mean (±SD) ERP of pathway(s) at baseline was 334 ms (±105 ms) on the initial study and 301 ms (±78 ms) on the f/u study.|
The shortest RR interval (±SD) during induced AF was 266 ms (±39 ms). Sustained AF was induced in 2/29 (7%) pts on the initial study and 11/29 (38%) pts on the f/u study.
|No ablation||Sustained paroxysmal SVT 2/29 (7%) (during 36-79 mo); 27/29 (93%) remained asymptomatic; 9/29 (31%) lost WPW pattern on the ECG.||36-79 mo||None|
|Leitch JW, et al., 1990 (20)|
|Group 1: Invasive EP study without catheter ablation||N/A||At baseline, the median ERP of the accessory pathway was 293 ms (IQR 280-310 ms), and the median retrograde ERP of the accessory pathway was 288 ms (IQR 240-320 ms).|
The median shortest RR interval during preexcited AF was 274 ms (IQR 240-325 ms) in 72 pts, was ≤250 ms in 23 pts, and was ≤200 ms in 8 pts.
AVRT was induced in 12/75 (16%), and sustained AF was induced in 23/75 (31%).
|No ablation||3/75 (4%) died of noncardiac causes, and 1/75 (1%) pt died suddenly after initial consultation but before EP study was done. 5/75 (7%) developed symptomatic AVRT. 1/75 (1%) developed symptomatic AF. The presence of sustained AVRT at EP study did not differentiate pts who remained asymptomatic from pts who became symptomatic. Only 1 (4%) pt developed clinical AF of the 23 pts in whom AF was induced at EP study.||Median 4.3 y (range 1-9 y)||None|
|Milstein S, et al., 1986 (22)|
|Group 1: Asymptomatic WPW pattern||N/A||43 accessory pathways in 42 asymptomatic pts. Mean (±SD) ERP of accessory pathway was 333±106 ms in asymptomatic pts vs. 298±42 ms in asymptomatic pts (p<0.025). Mean shortest RR interval during AF was 277±48 ms in the asymptomatic groups vs. 247±51 ms in the symptomatic group (p<0.025). Sustained AVRT could be induced in only 1 pt.||No ablation||1 pt died of metastatic carcinoma after 43 mo, and 1 pt died suddenly after he had agreed to participate in the study but before EP study could be performed. 4 pts received propranolol because of undocumented “skipped beats.” All other pts remained asymptomatic.||29±18 mo||None|
|Pappone C, et al., 2003 (21)|
|Group 1: Invasive EP study without catheter ablation||N/A||17/162 (10%) had multiple accessory pathways. Baseline mean (±SD) ERP was 275.2 ms (±33.8 ms). Isoproterenol mean (±SD) ERP was 246.1 ms (±30.5 ms). Shortest RR in AF was not reported.|
47/162 (29%) had inducible arrhythmia: nonsustained AF in 17, sustained AF in 19, and inducible AVRT that degenerated into totally pre-excited sustained AF in 11.
|No ablation||129/209 (62%) remained asymptomatic at the end of f/u, whereas 33 (16%) developed arrhythmic events: SVT in 25, AF in 8, documented VF in 3/209 (aborted sudden death in 2, both of whom had developed symptoms due to AF), and sudden death in 1/209||37.7±16.1 mo; range 14 to 60 mo||3/212 (1.4%); 47/212 who refused the 5-y EP study were excluded from the analysis.|
|Satoh M, et al., 1989 (23)|
|Group 1: Asymptomatic pts with WPW pattern||Intermittent pre-excitation on ECG recording 23%||Number of pts with multiple accessory pathways not reported. Baseline mean ERP of accessory pathway was 288±29 ms in asymptomatic pts. Shortest RR in AF not reported. AVRT was induced in 6/34 (18%) pts in the asymptomatic group, and sustained AF was induced in 2/34 (6%) of asymptomatic pts.||No ablation||Group 1: no events||Mean 15 mo (range 2 to 47 mo)||—|
|Santinelli V, et al., 2009 (16)|
|Group 1: Invasive EP study without catheter ablation||N/A||Anterograde ERP of accessory pathway ≤250 ms was present in 39/293 (13%) pts.|
Multiple accessory pathways were found in 13 (4%) pts.
Inducible arrhythmia was found in 47 (16%) pts.
|No ablation||262/293 (89%) pts did not experience arrhythmic events, remaining totally asymptomatic, whereas 31/293 (11%) pts had an arrhythmic event, which was potentially life threatening in 17 of them. Potentially life-threatening tachyarrhythmias resulted in resuscitated cardiac arrest (1 pt), presyncope (7 pts), syncope (4 pts), or dizziness (5 pts).||Median duration of f/u after EP study was 67 mo (range 8 to 90)||—|
|Pappone C, et al., 2014 (15)|
|Group 1: Asymptomatic pts with WPW pattern (they presented data on symptomatic pts and by whether catheter ablation of the accessory pathway was done, but the groups were not matched and selection bias was not adjusted for)||—||No ablation: Multiple accessory pathways in 59 (6%), median (IQR) ERP of accessory pathway 280 ms (250-300 ms). Inducible AVRT triggering AF on EP study was found in 47 (5%) of pts.|
With ablation: Multiple accessory pathways in 80 (7%), median ERP (IQR) of accessory pathway 280 ms (250-300 ms). Inducible AVRT triggering AF on EP study was found in 73 (6%) of pts.
|206/756 asymptomatic pts were treated with ablation; ablation was successful in 98.5%.||No ablation: during a median f/u of 22 mo, VF occurred in 13/550 (2%) asymptomatic pts (almost exclusively in children). During a median f/u of 46.5 mo, 48/550 (9%) additional asymptomatic pts experienced malignant arrhythmias, and 86/756 (11%) of the asymptomatic pts developed benign arrhythmias (AVRT and AF).|
With ablation: no pt developed malignant arrhythmias or VF over the 8 y of f/u.
|Median 96 mo||No ablation: completeness of f/u was 99.8% at 1 y and 92.3% at the end of the study|
With ablation: completeness of f/u was 95.5% at 1 y and 90.2% at the end of the study
AF indicates atrial fibrillation; AVNRT, atrioventricular nodal reentrant tachycardia; AVRT, atrioventricular reciprocating tachycardia; ECG, electrocardiogram/electrocardiographic; EP, electrophysiological; ERP, effective refractory period; f/u, follow-up; IQR, interquartile range; N/A, not applicable; pt, patient; SD, standard deviation; SVT, supraventricular tachycardia; VF, ventricular fibrillation; WPW, Wolf-Parkinson-White; and ---, not available.