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Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 August 1, 2017 e83 CLINICAL STATEMENTS AND GUIDELINES Recommendations for LQTS COR LOE Recommendations I B-NR Beta-blocker therapy, in the absence of contraindications, is indicated as a first-line therapy in patients with LQTS and suspected arrhythmic syncope.316–318 See Online Data Supplement 21. In the International Long QT Registry, patients who experienced ≥1 episode of syncope had a 6- to 12-fold increase in the risk of subsequent fatal/near-fatal events, independent of QTc duration. Beta-blocker therapy was associated with a significant reduction in the risk of recurrent syncope and subsequent fatal/near-fatal events. The response to beta blockers depends on the genotype, and not all beta blockers are the same.316,319 Patients with LQTS1 appear to respond better than patients with LQTS2 and LQTS3.316,320 IIa B-NR ICD implantation is reasonable in patients with LQTS and suspected arrhythmic syncope who are on beta-blocker therapy or are intolerant to beta-blocker therapy.317,320–324 See Online Data Supplement 21. Cardiac events can occur in patients receiving beta-blocker therapy, with a prevalence ranging from 10% to 32%, depending on the genotype.316,317 Many patients who appear to not respond to beta blockers are poorly compliant or do not tolerate the medication.317 Therefore, ICD implantation is reasonable in patients with LQTS who continue to have syncope despite beta-blocker therapy and in those who cannot tolerate beta-blocker therapy. In a study of 459 patients with genetically confirmed LQTS who received an ICD, syncope was a predictor of appropriate therapy.322 IIa C-LD Left cardiac sympathetic denervation (LCSD) is reasonable in patients with LQTS and recurrent syncope of suspected arrhythmic mechanism who are intolerant to beta-blocker therapy or for whom beta-blocker therapy has failed.325–327 See Online Data Supplement 21. LCSD has been shown to be associated with a large and significant clinical benefit in patients with symptomatic LQTS who are either refractory or intolerant to beta-blocker therapy.325,326 LCSD also reduces shocks in patients with an ICD during arrhythmia storms. Therefore, LCSD can be beneficial in patients with recurrent syncope despite beta blockade, in those who cannot tolerate beta-blocker therapy, and in those with frequent shocks from their ICD. However, LCSD alone does not completely prevent cardiac events, including SCD, during long-term follow-up. 4.3.4 Catecholaminergic Polymorphic Ventricular Tachycardia: Recommendations CPVT is characterized by the presence of catecholamineinduced (often exertional) bidirectional VT or polymorphic VT in the setting of a structurally normal heart and normal resting ECG.328,329 In patients with CPVT, 60% have a mu- tation in either the gene encoding the cardiac ryanodine receptor (RyR2) (autosomal dominant) or in the cardiac calsequestrin gene (CASQ2) (autosomal recessive).330–333 The prevalence of the disease is estimated to be around 0.1 per 1000 patients. Patients usually present in the first or second decade of life with stress-induced syncope.25 Recommendations for CPVT COR LOE Recommendations I C-LD Exercise restriction is recommended in patients with CPVT presenting with syncope of suspected arrhythmic etiology.328,334,335 See Online Data Supplements 22 and 23. The presence of VA in patients with CPVT has been shown to correlate with increases in heart rate, highlighting the role of the sympathetic nervous system in arrhythmogenesis.328,334 Therefore, exercise restriction, including avoidance of heavy exercise and competitive sports, is recommended in all patients with CPVT.335 I C-LD Beta blockers lacking intrinsic sympathomimetic activity are recommended in patients with CPVT and stress-induced syncope.329,334,336–339 See Online Data Supplements 22 and 23. Beta blockers should be first-line therapy in patients with CPVT, as they have been shown to suppress exercise-induced arrhythmias. However, they are not always completely protective.329,334,336 The variability in outcome with beta-blocker therapy is due to multiple factors, including dosing and compliance.337,338 Repeat exercise testing and cardiac monitoring to document arrhythmia suppression can be reassuring.334,339 IIa C-LD Flecainide is reasonable in patients with CPVT who continue to have syncope of suspected VA despite beta-blocker therapy.319,320 See Online Data Supplements 22 and 23. Despite beta-blocker therapy, breakthrough arrhythmias occur in patients with CPVT because of treatment failure, noncompliance, and subtherapeutic dosing. The addition of flecainide to conventional therapy has been shown to partly or completely suppress exerciseinduced VA.340 In patients intolerant of beta-blocker therapy, flecainide is useful as monotherapy.341 IIa B-NR ICD therapy is reasonable in patients with CPVT and a history of exercise- or stress-induced syncope despite use of optimal medical therapy or LCSD.271,342,343 See Online Data Supplements 22 and 23. ICD therapy appears to reduce mortality rate in patients with CPVT and syncope or VA refractory to medical therapy. However, VT storms in patients with CPVT may not always respond to ICD shocks,344 and shocks may precipitate early recurrence of arrhythmia because of their painful nature with resultant adrenergic state. Furthermore, the effectiveness of ICD shock therapy in CPVT depends on the mechanism of the VA, with greater success noted when shocks are delivered for VF.345 ICD implantation should be performed in conjunction with beta-blocker therapy or LCSD when available.342 Careful programming, including long detection intervals with high cutoff rate, is recommended to decrease the prevalence of inappropriate shocks.342,343 IIb C-LD In patients with CPVT who continue to experience syncope or VA, verapamil with or without beta-blocker therapy may be considered.346,347 See Online Data Supplements 22 and 23. Verapamil alone or in combination with beta blockers helps suppress arrhythmias in patients with CPVT,347 including delaying the onset of exercise-induced ventricular ectopy.346,347 Downloaded from http://ahajournals.org by on October 7, 2026