Introduction Sarcoidosis is a multi-systemic inflammatory disorder characterised by non-caseating granulomata. Cardiac sarcoidosis (CS) is typified by the presence of myocardial inflammation and confers adverse prognosis, as it can be associated with conduction abnormalities, congestive heart failure, ventricular arrhythmias (VA) and sudden cardiac death. European Society of Cardiology (ESC) guidelines advocate implantable cardioverter-defibrillator (ICD) implantation with concurrent cardiac resynchronisation therapy as a Class IIa indication in patients with CS that have an indication for permanent pacing with left ventricular ejection fraction (LVEF) <50%.

Purpose Although established guidelines advocate ICD implantation in specific sub-cohorts, there remains a paucity of data on outcomes. We conducted a systematic review of published literature to assess outcomes in patients with CS treated with ICD.

Methods Observational studies of patients with definite or probable CS and ICD implantation were identified from multiple databases from inception to 21st May 2021. Relevant studies were scrutinised for inclusion and data extraction was performed using a pre-specified template. The primary outcome of interest was appropriate ICD therapies with a secondary outcome of all-cause mortality.

Results Eight retrospective, non-randomised studies were identified, comprising 530 patients with follow-up period of 24 to 66 months (weighted average 40 months). Mean age was 53.9 years with average ejection fraction of 41.3%. Overall incidence of appropriate therapy, reported in all studies, was 38.1% during the follow-up period. Left ventricular systolic dysfunction (LVSD) with ejection fraction < 40% was a predictor of appropriate therapy in the majority of studies, as were sustained VA during electrophysiological testing (EP) in one study. All-cause mortality was reported in six studies, with incidence of 6.0% over a median follow-up period of 42 months; only two mortality events were linked to a primary arrhythmic cause.

Conclusions Appropriate ICD therapies in patients with CS is commonly associated with LVSD, which may act as a surrogate for scar burden. The utility of EP testing in this setting remains unclear.

Conflict of Interest No