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September 25, 2018 Circulation. 2018;138:e272–e391. DOI: 10.1161/CIR.0000000000000549 e320

CLINICAL STATEMENTS AND GUIDELINES presence of inflammation and RV involvement on PET scanning was associated with increased risk of death or e g of relatives.S7.6-10 Electrophysiological studies in a series of 76 patients with evidence of cardiac sarcoid found that 11% had inducible VT. During a median follow-up of 5 years, 75% of patients with inducible VT had spontaneous VT or death compared with 1.5% of those who did not have inducible VT.S7.6-18

3.	 Electrophysiological study has been proposed as a potential tool for risk stratification of VA and SCD in patients who had demonstrable evidence of cardiac sarcoidosis based on imaging studies or biopsy, but do not have documented arrhythmias or arrhythmic symptoms nor meet standard primary prevention criteria for ICD implantation.

One study evaluated 76 patients with documented cardiac sarcoidosis by PET or cardiac MRI who underwent electrophysiological study.S7.6-12 Eight (11%) were inducible for sustained VAs and received an ICD, while the rest did not receive an ICD because they were not inducible. LVEF was lower in patients with inducible VA (36.4 + 4.2% versus 55.8 + 1.5%). Over a median follow-up of 5 years, 6 of 8 patients in the group with inducible VA had VA or died, compared with 1 death in the negative group.S7.6-12 An important caveat is that it remains unclear if electrophysiological study is more predictive than LVEF alone, because inducibility appears to reversely correlate with LVEF. Furthermore, in this study the average LVEF of the inducible patients declined further during the followup period.S7.6-12 4.	 In addition to VA and LV dysfunction, conduction abnormalities, including heart block, can also be a common manifestation of cardiac sarcoidosis. Patients with documented VA and LV dysfunction are at increased risk of cardiac events including cardiac death. One study compared outcomes in 22 patients with high-degree atrioventricular block as the initial manifestation of cardiac sarcoidosis, to 31 patients who initially presented with VT and/or HF. After a median follow up of 34 months, the patients who presented with heart block had fewer HF hospitalization, yet fatal cardiac events, including sustained VAs, were similar to those with VT and/or HF, suggesting that the risk of fatal cardiac events is high regardless of the initial clinical presentation.S7.6-13 In the same study, administration of steroids led to some clinical improvement, with some patients recovering conduction, yet steroid effectiveness was not universal and did not seem to be protective against adverse cardiac events.S7.6-13 5.	 Several studies have attempted to evaluate the role of immunosuppression for reducing VA in patients with cardiac sarcoidosis, but results have been inconsistent.S7.6-14–S7.6-16 Furthermore, a worsening of VA has been reported with immunosuppressive therapy (usually glucocorticoids) in a number of patients, including electrical storm developing in some within 12 months of initiating therapy.S7.6-15 One study reported a decrease of arrhythmia burden with steroid therapy but only when given in the early stages of the disease; those with advanced LV dysfunction did not experience benefit.S7.6-16 A systematic combined treatment approach was successful in 63% of patient in a series in which medical therapy included both steroids and antiarrhythmic medications, followed by radiofrequency catheter ablation if needed.S7.6-14 Immunosuppressive therapy may serve a dual purpose beyond arrhythmia effects as it may help stabilize disease progression and prevent further deterioration of LV function, although this has yet to be demonstrated in RCTs. Steroids do not appear to reverse advanced ventricular dysfunction once present, which supports the importance of early diagnosis and intervention.S7.6-1 PET scanning for assessing inflammation and scar is being increasingly used in sarcoidosis as well, but data supporting its use for guiding therapy of arrhythmias are limited.

7.6.1 Other Infiltrative Cardiomyopathies

Infiltrative cardiomyopathies are a heterogeneous group of uncommon systemic diseases with associated cardiac involvement. In some infiltrative cardiomyopathies, such as Fabry’s disease, VAs are uncommon. Some, such as hemochromatosis, are highly treatable especially when diagnosed early. In all cases, treatment of the underlying condition must accompany management of cardiac arrhythmias. Most studies of infiltrative cardiomyopathies and arrhythmias are small and observationalS7.6.1-1 but, in general, unless contraindications are present, VAs should be treated as in any other cardiomyopathy. See Section 7.6 for sarcoidosis. Until recently, cardiac amyloidosis was associated with a very poor prognosis with patients ultimately succumbing to progressive HF.S7.6.1-2 This perception is changing with advances in medical therapy for light-chain amyloidosis, which have led to improved outcomes.S7.6.1-3 Yet, decisions must be individualized because data remain too limited to allow formal recommendations as published reports on ICD effectiveness in amyloidosis are small, observational and with limited follow up.S7.6.1-4 Whether there is greater benefit to ICD placement in light chain amyloidosis versus transthyreitin-related amyloidosis remains uncertain, because most studies included mainly patients with amyloid light-chain amyloidosis for which the rate of VA may be greater and prog-

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