Intravenous adenosine is recommended for acute treatment in ACHD patients and SVT.207,463 465 See Online Data Supplement 20. Observational studies support the use of adenosine to terminate AVNRT, SVT using an accessory pathway, and some forms of focal AT. These mechanisms account for <25% of SVT in adults with repaired congenital disease.207,463 Intravenous adenosine is unlikely to terminate atrial reentry tachycardia or atrial flutter, which represents >70% of SVT episodes in this population, but it may be diagnostic by producing transient AV block, which would make the atrial activity visible.464,465 Page et al 2015 ACC/AHA/HRS SVT Guideline e551 9.2.3. Ongoing Management: Recommendations Recommendations for Ongoing Management of SVT in ACHD Patients COR LOE Recommendations I C-LD Ongoing management with antithrombotic therapy is recommended in ACHD patients and AT or atrial flutter to align with recommended antithrombotic therapy for patients with AF.365 See Online Data and 17. The risk of stroke associated with AF is well established, and several RCTs have demonstrated the efficacy of anticoagulation for stroke prevention in patients with additional risk factors.366 Anticoagulation has also been shown to prevent stroke when administered during the weeks immediately before and after cardioversion.31,367 Whether atrial flutter carries a risk of stroke similar to that in patients with AF has been debated in the past but is now supported by limited evidence from mechanistic, observational, and prospective studies that include patients primarily with atrial flutter.365 369 Several reports have suggested that the risk of stroke in patients with atrial flutter is mitigated by anticoagulation. 