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8.2 Ongoing Management: Recommendations

9 Special Populations

9.1 Pediatrics

As discussed in the Scope (Section 1.4), the present document is aimed at the adult population (≥18 years of age) and offers no specific recommendations for pediatric patients. Nevertheless, a brief discussion of SVT in pediatric patients is included below, highlighting major considerations with regard to SVT in younger patients, including adolescent patients. SVT in young patients varies significantly from SVT in adult patients in terms of mechanism, risk of developing heart failure or cardiac arrest, risks associated with interventional therapy, natural history, and psychosocial impact. Approximately half of pediatric SVT presents in the first 4 months of life, with age-related peaks in occurrence subsequently at 5 to 8 years and after 13 years. Accessory pathway– mediated tachycardia accounts for >70% of SVT in infants, decreasing to approximately 55% in adolescents.56,407–409 AVNRT increases with age, from 9% to 13% of SVT in infants, to 30% to 50% of SVT in teenagers. After 12 years of age, women are more likely to have AVNRT than men, and overall SVT is less frequent among African American and Hispanic patients than in the general pediatric population.56 Atrial flutter is seen in some neonates and in older children is predominantly observed after congenital heart disease. AF is uncommon in childhood, accounting for <3% of supraventricular arrhythmias, and may be a consequence of AVRT or AVNRT in adolescents or may be associated with repaired congenital heart disease. 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 support 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 2 decades of life.60,254–257 The risk of cardiac arrest is higher in patients with AVRT precipitating AF, short accessory connection refractory periods, and posteroseptal accessory pathways.60,254–257 Notably, the absence of prior symptoms does not preclude risk because cardiac arrest may be the initial manifestation 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 longterm 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. Junctional tachycardia caused by enhanced automaticity may be suppressed as effectively by diltiazem and verapamil as by beta blockers. In 1 study of an adult patient on a regimen of oral verapamil, procainamide, and digoxin in combination for prophylactic therapy, junctional tachycardia could not be induced by either atrial or ventricular overdrive pacing, programmed electrical stimulation, or isoproterenol.397 Less is known about oral diltiazem than verapamil, but it likely has a similar efficacy. IIb C-LD 1.  Flecainide or propafenone may be reasonable for ongoing management in patients without structural heart disease or ischemic heart disease who have junctional tachycardia.398,399

See Online Data Supplement 19. Studies supporting the use of flecainide for long-term control of junctional tachycardia were performed at a time when intravenous flecainide was given for acute control, followed by a transition to chronic oral therapy.398 Although the only data for propafenone stem from case series in infants and children, given that flecainide and propafenone reduce automaticity from the ectopic focus in the AV junction, either agent is reasonable, provided patients do not have structural heart disease or ischemic heart disease.213,400,401 IIb C-LD 2.  Catheter ablation may be reasonable in patients with junctional tachycardia when medical therapy is not effective or contraindicated.131,132,396,402–405

See Online Data Supplement 19. Radiofrequency ablation has been performed as a potentially curative therapy for junctional tachycardia since the early 1990s. However, in view of the reported 5% to 10% risk of AV block, catheter ablation is generally reserved for highly symptomatic patients in whom drug therapy has been ineffective or not tolerated (Table 8). Many practitioners use cryoablation as an alternative to radiofrequency ablation.132 Given that it is often difficult to distinguish junctional tachycardia from AVNRT on the ECG, EP study with the goal of ablation may be a helpful diagnostic and potentially therapeutic intervention. Junctional tachycardia may be observed during and after slow-pathway ablation of AVNRT, because of irritation of the compact AV node.406 This iatrogenic junctional tachycardia is transient and generally benign and can be distinguished from AVNRT through pacing maneuvers at EP study.396,405 It is crucial to recognize this phenomenon at the time of EP study because attempts to ablate the junctional tachycardia are unnecessary and could result in AV block.

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