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Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 August 1, 2017 e81 CLINICAL STATEMENTS AND GUIDELINES 4.2.4 Arrhythmogenic Right Ventricular Cardiomyopathy: Recommendations Recommendations for ARVC COR LOE Recommendations I B-NR ICD implantation is recommended in patients with ARVC who present with syncope and have a documented sustained VA.274–278 See Online Data Supplement 17. ICD indications in patients with ARVC and sustained VA are no different than guidelines-based indications for secondary prevention of SCD in other diseases.12 IIa B-NR ICD implantation is reasonable in patients with ARVC who present with syncope of suspected arrhythmic etiology.274,275,277–279 See Online Data Supplement 17. Unexplained or arrhythmic-appearing syncope in patients with ARVC has consistently been associated with increased risk of SCD or appropriate therapy after ICD implantation in multiple observational studies.274–279 4.2.5 Cardiac Sarcoidosis: Recommendations Recommendations for Cardiac Sarcoidosis COR LOE Recommendations I B-NR ICD implantation is recommended in patients with cardiac sarcoidosis presenting with syncope and documented spontaneous sustained VA.12,280–286 See Online Data Supplement 18. ICD indications in patients with cardiac sarcoidosis and sustained VA are no different than guidelines- or consensus-based indications for secondary prevention of SCD.12,286 Macroreentry around the granulomas is the most common mechanism of VA in patients with cardiac sarcoidosis.280,281 Other mechanisms include triggered activity and abnormal automaticity due to myocardial inflammation.282 Unlike AV block, the results of immunosuppression in patients with VA are controversial. Some studies have shown improvement with immunosuppression,283 whereas others have shown no benefit and even harm due to worsening VA and aneurysm formation.284,285 I C-EO In patients with cardiac sarcoidosis presenting with syncope and conduction abnormalities, GDMT is recommended.12,286–289 See Online Data Supplement 18. Patients with cardiac sarcoidosis and conduction abnormalities should be treated according to the most recent guidelines for cardiac pacing.12 Patients with cardiac sarcoidosis and conduction abnormalities have a worse prognosis than that of patients with idiopathic AV block.286,287 Immunosuppression can result in transient reversal of AV block; however, the reversibility is unpredictable.287–289 As such, it is recommended to proceed with pacing according to the most recent guidelines regardless of AV block reversibility. IIa B-NR ICD implantation is reasonable in patients with cardiac sarcoidosis and syncope of suspected arrhythmic origin, particularly with LV dysfunction or pacing indication.290–293 See Online Data Supplement 18. The presence of myocardial noncaseating granulomas and inflammation puts patients at risk of having both AV block and VA, particularly in the presence of LV dysfunction. Patients with cardiac sarcoidosis and mild-to-moderate LV dysfunction have a substantial risk of developing VA.290–293 In a multicenter study including 235 patients with cardiac sarcoidosis who received ICD therapy for primary or secondary prevention, including patients with syncope, 36% of patients received appropriate ICD therapy. Patients who received appropriate ICD therapies were more likely to be male and to have a history of syncope, lower LV ejection fraction, ventricular pacing on baseline ECG, and a secondary prevention indication than were those who did not receive appropriate ICD therapies.292 Therefore, given the presence of a substrate for VA in patients with cardiac sarcoidosis, ICD implantation is reasonable in patients presenting with syncope suspected to be of arrhythmic origin. IIa B-NR EPS is reasonable in patients with cardiac sarcoidosis and syncope of suspected arrhythmic etiology.294 See Online Data Supplement 18. In patients with cardiac sarcoidosis, programmed electrical stimulation may help identify patients at risk of having VA. According to a study of 76 patients with cardiac sarcoidosis and no cardiac symptoms, 8 (11%) had inducible sustained VA. During a median follow-up of 5 years, 6 of 8 had VA or died, versus 1 of 68 in the noninducible group.294 4.3 Inheritable Arrhythmic Conditions: Recommendations The prevalence of inherited arrhythmic conditions is low, rendering the clinical significance of an abnormal test a challenge. Few syncope-specific studies exist. Most studies of patients with inherited arrhythmias are open label or not randomized and often are uncontrolled. Most of the publications included other cardiac events, such as cardiac arrest and death, either at enrollment or as an outcome. Syncope of suspected arrhythmic cause has been correlated with increased risk of SCD, cardiac arrest, or overall cardiac death. Although ICD is effective in aborting cardiac arrest and presumably reducing risk of death in the patients with inheritable rhythm disorders, its impact on syncope recurrence is unknown.25,26,220 4.3.1 Brugada Syndrome: Recommendations Brugada syndrome is defined as a genetic disease characterized by an increased risk of SCD and ST elevation with type 1 morphology ≥2 mm in ≥1 lead among the right precordial leads V1 and V2, occurring either spontaneously or after intravenous administration of Class I antiarrhythmic drugs. The prevalence is higher in Asian countries than in North America or Western Europe, ranging from 0.01% to 1.00%, with a significant male predominance.295 Downloaded from http://ahajournals.org by on October 7, 2026