Symptoms of SVT vary with age: gastrointestinal or respiratory findings in infants, chest or abdominal pain in the younger child, and palpitations in the adolescent. Congestive heart failure is present in up to 20% of infants and in older children with incessant tachycardia and in rare cases may necessitate mechanical cardiopulmonary sup- port during initial therapy.410 Pre-excitation is present in 20% to 35% of children with SVT. The risk of ventricular fibrillation or SCD related to WPW in childhood is 1.3% to 1.6% and is highest in the first The risk of cardiac arrest is higher in patients with AVRT precipitating AF, short accessory con- nection refractory periods, and posteroseptal accessory path- Notably, the absence of prior symptoms does not preclude risk because cardiac arrest may be the initial mani- festation of pre-excitation.254,257,411 Risk stratification, such as with ambulatory 24-hour monitoring or treadmill exercise testing, is often considered for children with pre-excitation to assess persistence of pre-excitation.412 Pharmacological therapy of SVT in childhood is largely based on practice patterns because RCTs of antiarrhythmic medications in children are lacking. AV nodal blocking drugs are widely used for the most common arrhythmias, AVRT, and Recommendations for Ongoing Management of Junctional Tachycardia COR LOE Recommendations IIa C-LD 1. Oral beta blockers are reasonable for ongoing management in patients with junctional tachycardia.388 See Online Data Supplement 19. Beta blockers are often used as first-line chronic therapy for junctional tachycardia because of the important proarrhythmic effects and long- term toxicity of other agents that have been shown to be effective.389,398,399 When junctional tachycardia is paroxysmal, attention should be directed toward avoiding the potential for bradyarrhythmias and hypotension when beta-blocker therapy is initiated. IIa C-LD 2. Oral diltiazem or verapamil is reasonable for ongoing management in patients with junctional tachycardia.397 See Online Data Supplement 19. 