In patients with recurrent sustained monomorphic VT, catheter ablation of VT can be effective.S10.8-21 S10.8-25 Hemodynamic repair, at the time that an arrhythmia is being ablated surgically, should be considered. For patients with complex adult congenital heart disease, care should be provided at experienced centers. After successful catheter ablation of VT, implantation of an ICD for those who do not have an ICD is an individu- alized decision based on overall functional and physi- ological status and shared decision making. Careful monitoring during follow-up for recurrent arrhyth- mias is essential. 8. The highest risk of SCD associated with repaired congenital heart disease reported from large con- temporaneous cohorts is in patients with transpo- sition of the great arteries with atrial baffle repair, Ebstein anomaly of the tricuspid valve, aortic ste- nosis, and univentricular physiology.S10.8-44 S10.8-47 Patients with Senning or Mustard atrial baffle repairs are at an increased risk for SCA, particularly The atrial baffle is noncom- pliant restricting ability to augment volume and may be associated with pulmonary vein stenosis and increased end-diastolic pressures. RV ischemia and infarction occur, with perfusion defects identi- fied by myocardial perfusion studies in >40% of patients in this population.S10.8-49,S10.8-50 Risk factors for cardiac arrest in patients with transposition and atrial baffle repairs include prior ventricu- lar septal defect closure, symptoms of HF, atrial arrhythmia, RVEF <30% to 35%, and QRS dura- In the single multicenter study assessing outcomes after implantation of an ICD in patients with prior atrial baffle repair of transposition of the great arteries, the lack of beta blockers was associated with a high risk of appro- priate ICD therapy.S10.8-26 Atrial arrhythmias fre- quently precede VT in transposition patients, and treatments for atrial tachycardia including cath- eter ablation, antitachycardia pacing algorithms, and beta blockers are important to reduce ICD 9. 