Ethnic differences in baseline phenotype among patients with cardiac sarcoidosis: a single-centre UK cohort study

Introduction Cardiac involvement affects up to 30% of patients with systemic sarcoidosis yet remains under-recognised, with diagnostic delay contributing to adverse outcomes. US data suggest Black patients present with more severe disease; however, the influence of ethnicity on baseline cardiac sarcoidosis phenotype remains incompletely characterised, particularly within multi-ethnic UK populations served by a universal healthcare system. Purpose To explore ethnic differences in baseline phenotype among UK patients with CS Methods This retrospective cohort study included consecutive patients assessed at a WASOG referral centre (2022–2025) who received a high-confidence CS diagnosis following multidisciplinary review in accordance with Heart Rhythm Society criteria. Demographic data, Index of Multiple Deprivation (IMD) deciles, ECG and echocardiographic parameters, Holter findings, and device status were extracted from electronic health records. Categorical variables were compared using χ² or Fisher’s exact tests; continuous variables using non-parametric tests. Results Among 221 referrals, 108 patients (mean age 59.8 ± 12.3 years) were diagnosed with CS. The cohort was predominantly male (81/108, 75%) and White (69/108, 64%). Female representation was proportionally higher among Black patients (10/23, 44%) compared with White patients (16/69, 23%), whereas South Asian patients demonstrated marked male predominance (15/16, 94%; Fisher’s exact p = 0.028). Significant ethnic differences were observed in socioeconomic status. Black patients more frequently resided in deprived areas, followed by South Asian patients, while White patients had higher socioeconomic status (mean IMD decile: Black 2.9 ± 1.9 vs South Asian 4.4 ± 2.5 vs White 5.2 ± 2.6; p = 0.004). Baseline cardiac phenotype also varied by ethnicity. Black patients had lower mean left ventricular ejection fraction (p = 0.021) and were more frequently categorised with severe LV systolic dysfunction (10/23, 44%) compared with White (14/69, 20%) and South Asian patients (1/16, 6%), who had the lowest prevalence of LV impairment (χ² = 8.21, p = 0.016). Male sex was independently associated with impaired LV systolic function (χ² = 6.30, p = 0.044). Despite differences in ventricular function, no significant association was observed between ethnicity and arrhythmic manifestations, including heart block, ventricular arrhythmia, or atrial arrhythmia (χ² = 4.88, p = 0.087). Conclusions In this regional UK cohort, CS phenotype differed by ethnicity. Black patients, with greater female representation, experienced higher socioeconomic deprivation and more severe LV systolic impairment at presentation. South Asian patients were predominantly male and had lower rates of LV dysfunction. These findings support ethnicity-stratified phenotyping in CS to refine risk assessment and management and suggest healthcare-related determinants may influence patterns of presentation.