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September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e314

CLINICAL STATEMENTS AND GUIDELINES transplantation.S7.3-1 However, the identification of a pathogenic mutation facilitates targeted genetic screening for that mutation in firstdegree relatives, that may identify approximately 60% to 70% as gene positive,S7.3-1 highest among siblings, and those with symptoms.S7.3-4 Screening for the specific mutation can identify some gene positive family members prior to disease expression, while relieving others from the need for lifestyle changes and long-term monitoring.S7.3-2,S7.3-3

7.	 Syncope is reported in 16% to 39% of arrhythmogenic right ventricular cardiomyopathy patients at the time of diagnosis,S7.3-13,S7.3-14,S7.3-16,S7.3-41,S7.3-43 is frequently exercise-related, and has been associated with high arrhythmic risk in some studies.S7.3-10,S7.3-41 Among patients with arrhythmogenic right ventricular cardiomyopathy and implanted ICDs, syncope was an important predictor of appropriate shocks in 1 study,S7.3-10 but not in other studies.S7.3-9,S7.3-12,S7.3-13,S7.3-43 Studies have not provided information about ventricular function or abnormalities on ECG in patients with syncope, limiting its assessment as an independent risk factor. Syncope may be a harbinger of progression of underlying disease and should be integrated into the decision-making process for ICD implantation with the patient. 8.	 Asymptomatic patients with arrhythmogenic right ventricular cardiomyopathy and no VA or ventricular dysfunction are generally observed without antiarrhythmic therapy other than beta-blocker therapy, with ongoing periodic reassessment for the development  of arrhythmias or ventricular dysfunction.S7.3-46,S7.3-47 Atenolol was shown to reduce VA in 1 study.S7.3-15 Ambulatory monitoring and/or exercise testing can be performed to assess adequacy of beta-blocking dosing. 9.	 Interrogation of ICDs shows that >90% of spontaneous sustained VTs in arrhythmogenic right ventricular cardiomyopathy are monomorphic,S7.3-12 while sustained monomorphic VT is inducible at electrophysiological study in 55% of patients.S7.3-36 VT is usually related to scar-related reentry, and the subepicardium usually has more extensive scar than the endocardium.S7.3-27 In experienced centers, use of epicardial mapping and ablation is associated with  better outcomes.S7.3-27,S7.3-28,S7.3-30,S7.3-31,S7.3-33 Important complications including pericardial tamponade, MI, and death occur in 2.3% to 3.3% of ablation cases,S7.3-27–S7.3-29 emphasizing the need for performance in centers with specialized expertise in epicardial procedures. Ablation reduces the frequency of recurrent VT, although 27% to 55% of patientsS7.3-27,S7.3-28 have at least 1 recurrence; ablation of VT in arrhythmogenic right ventricular cardiomyopathy patients does not eliminate the need for an ICD in appropriate candidates. The potential risk of VT recurrence due to disease progression should be reviewed with patients when considering ablation. There are no randomized comparisons of antiarrhythmic therapy to suppress recurrent VT. Beta blockers, sotalol and amiodarone have been used.S7.3-15 In an observational series, sotalol suppressed inducible VT in 58% of patients with  <10% of patients experiencing arrhythmia recurrence during follow-up.S7.3-48 Effectiveness of the different medications appears to be variable, and so more studies are needed. 10.	 In arrhythmogenic right ventricular cardiomyopathy, areas of fibrofatty scar in the RV free wall create areas of delayed ventricular activation causing fractionated deflections following the QRS, known as epsilon waves on the surface ECG (a major criterion) and late potentials in the signal averaged ECG (minor criterion) in the 2010 Task Force Criteria for diagnosis of arrhythmogenic right ventricular cardiomyopathy.S7.3-6 When the standard ECG QRS duration is ≤110 ms, criteria for abnormal signal-averaged ECG include any 1 of the following: filtered QRS duration ≥114 ms, duration of the terminal QRS <40 uV exceeding 37 ms, or a root mean square voltage in the terminal 40 ms of ≤20 uV.S7.3-6 Abnormal findings on signal averaged ECG correlated with disease severity on cardiac MRI,S7.3-35 and increased adverse events in males.S7.3-34 In an assessment of the diagnostic use of testing for arrhythmogenic right ventricular cardiomyopathy, signal averaged ECG was of greater value than cardiac MRI or biopsy.S7.3-14

11.	 The value of an electrophysiological study is uncertain in asymptomatic arrhythmogenic right ventricular cardiomyopathy patients with preserved ventricular function in predicting subsequent risk for SCD. Studies of programmed ventricular stimulation in patients with definite or probable arrhythmogenic right ventricular cardiomyopathy include most symptomatic patients, making recommendations on asymptomatic patients difficult. Electrophysiological studies induce sustained VT in approximately 60% of patientsS7.3-10,S7.3-36; many of whom have had prior spontaneous episodes of sustained VT. In patients with primary prevention ICDs, inducible sustained VT did not predict subsequent appropriate ICD shocks.S7.3-13 In 1 study including symptomatic patients, patients without inducible VT were less likely to receive appropriate ICD shocks.S7.3-9 In asymptomatic patients without evidence of VA on ambulatory monitoring, a negative electrophysiological study may have limited value in decision-making for an ICD.

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