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IIa B-NR 1. Preoperative catheter ablation or intraoperative surgical ablation of accessory pathways or AT is reasonable in patients with SVT who are undergoing surgical repair of Ebstein anomaly.479–485 See Online Data Supplement 20. The prevalence of SVT among patients with Ebstein anomaly was 33% in 1 large series, the highest noted among ACHD patients,440 and increased with age. AT, atrial flutter, or AF develops in ≥50% of patients with Ebstein anomaly and significant tricuspid regurgitation. Right-sided accessory pathways are present in 15% to 30% of patients with Ebstein anomaly and may be multiple in up to ≥29% of those patients. Catheter ablation of accessory pathways in patients with Ebstein anomaly is associated with lower success rates than for other populations, acute success rate of 75% to 89% of procedures, with acute recurrence in 25% to 30%.480,481 In a series of 83 adults undergoing arrhythmia surgery at the time of surgical repair of Ebstein anomaly, accessory pathways were present in 32%, and atrial flutter/fibrillation was noted in 54%,483 with no recurrence of AP after surgery. Successful surgical ablation of accessory pathways has been reported in 92% to 100%.483,484 In a series of patients undergoing right atrial maze procedures or isthmus ablation for atrial flutter/fibrillation in association with repair of Ebstein anomaly, freedom from recurrent flutter/fibrillation was 75% during 34 months of follow-up.483 In a comparison study of combined operative arrhythmia surgery with repair, versus catheter ablation followed by surgical repair, the combined approach was effective in 94% of cases versus 76% of patients treated with the catheter approach alone.484 In a series of patients undergoing repair of Ebstein anomaly, patients who underwent preoperative EP study with intraoperative ablation of arrhythmia substrate had lower risk of SCD than patients without arrhythmia intervention.479 In patients with Ebstein anomaly undergoing planned surgical intervention, an integrated approach of arrhythmia intervention has been demonstrated to be safe and effective. IIa B-NR 2. Oral beta blockers or sotalol therapy can be useful for prevention of recurrent AT or atrial flutter in ACHD patients.218,447,486 See Online Data Supplement 20. Beta blockers may decrease catecholamine-related triggers and provide AV nodal blockade during recurrent atrial arrhythmias. One study of adults with transposition of the great arteries and prior atrial switch repairs with implanted defibrillators demonstrated SVT preceding VT in 50% of patients; use of beta-blocker medications in this population was associated with decreased incidence of appropriate defibrillator shocks.486 Observational studies on the use of sotalol in ACHD patients report freedom from recurrent AT in 41% to 46% of patients during short-term follow-up.218,487,488 Use of either medication in the setting of significant sinus node dysfunction may exacerbate bradycardia and requires careful monitoring. Initiation of sotalol in this population is recommended during inpatient monitoring for proarrhythmia for 48 to 72 hours. IIa B-NR 3. Catheter ablation is reasonable for treatment of recurrent symptomatic SVT in ACHD patients.330,449,452,454,457,458,489–492 See Online Data Supplement 20. Multiple observational and multicenter studies have demonstrated acute success rates between 65% and 100% for treatment of SVT associated with ACHD.452,454,455,457,489,493,494 Acute success rates vary by tachycardia mechanism and type of congenital heart disease and repair. Success rates are highest for SVT associated with AVNRT (>80%),490,494 accessory pathways (75% to 89% among patients with Ebstein anomaly),480 or focal AT (80% to 100%).492,494,495 Success rates for catheter ablation of AT or atrial flutter are significantly lower than that reported in patients without ACHD, with overall 65% to 82% acute success in mixed anatomic substrates,452,454,455,457,493,494 but success rates have improved with advanced mapping and ablation techniques.494 Acute success rates in ablation of AT or atrial flutter varies significantly by type of congenital heart disease, ranging from 93% to 100% in patients with repaired ASD,330,449,458 85% to 100% in atrial baffle repairs of transposition of the great arteries,490,492 and 54% to 75% of univentricular heart or Fontan repairs.457,490,495 Older age and presence of univentricular heart physiology was associated with decreased acute success rates in a series of 193 ablations of AT.457 Recurrent AT has been reported in 20% to 85% of patients during short-term follow-up, with development of AF reported in 7% to 30% of patients.330,449,454,493 Recurrent SVT may represent the same or a new reentrant circuit, and arrhythmia burden may be decreased by ablation procedures. Ablation procedures in patients with complex congenital heart disease are best performed in centers with advanced mapping techniques and expertise in congenital heart disease.25,29,496 IIa B-NR 4. Surgical ablation of AT or atrial flutter can be effective in ACHD patients undergoing planned surgical repair.497–508 See Online Data Supplement 20. In patients with symptomatic SVT undergoing planned surgical repairs of structural heart disease or ischemic heart disease, observation studies report that arrhythmia surgery can be integrated into the operation with high efficacy and without increased surgical morbidity.497–500 In populations including those with tetralogy of Fallot/double-outlet right ventricle, tricuspid valve repairs, and ASD, rates of freedom from recurrent AT or atrial flutter have been reported as 73% to 93% without antiarrhythmic medications during medium-term follow-up of 2.5 to 10 years. Catheter ablation may be attempted in specialized centersbefore surgical Fontan repair. There are no RCTs comparing efficacy of catheter versus surgical ablation of AT or atrial flutter in patients with prior Fontan repairs. The incidence of AT or atrial flutter in patients with prior Fontan repairs approaches 60% and increases with advancing age. Catheter ablation success rates in this subset of patients are lower than for other lesions,457 with acute success in 54% to 75%, and with recurrent AT in 27% to 50% of patients within 2 to 4 years490,495; death or transplantation was reported in 27% during follow-up. Several observational studies of surgical resection and ablation for AT or atrial flutter associated with Fontan conversion reported rates of freedom from AT of 12% to 16% during follow-up extending to 8 years501–505; death or transplantation was reported in 6% to 14% during follow-up. Performance of a modified right atrial maze procedure versus CTI ablation was associated with lower recurrence rates.501 Alternatively, surgical repairs without arrhythmia intervention are associated with high recurrence rates of AT. Arrhythmia surgery can be combined with hemodynamic surgical revision with low mortality rate and improved medium-term freedom from arrhythmia recurrence and deathin this population. IIb B-NR 1. Atrial pacing may be reasonable to decrease recurrences of AT or atrial flutter in ACHD patients and sinus node dysfunction.472,509,510 See Online Data Supplement 20. Small observational studies support the use of atrial pacing in patients with recurrent AT or atrial flutter to reduce the frequency of tachycardia episodes. The pacing rate is programmed to maintain atrial pacing for the majority of the time in patients with sinus node dysfunction, significantly reducing tachycardia recurrences to 11% in 1 study.509,510 In addition, the implanted pacemaker can be used for termination of recurrent episodes of AT or atrial flutter.472 Recommendations for Ongoing Management of SVT in ACHD Patients (Continued) COR LOE Recommendations Downloaded from http://ahajournals.org by on October 7, 2026