Sarcoidosis with cardiac involvement: whoever searches will find

<bold>Introduction:</bold> Sarcoidosis with cardiac involvement is rare, potentially life-threatening and its true prevalence still unknown. This study is designed to investigate epidemiological data on hospitalized cardiac sarcoidosis in Switzerland. <bold>Methods:</bold> ICD-10 diagnoses and in-hospital mortality of patients between 2010 and 2021 were extracted from a nation-wide database provided by the Swiss Federal Statistical Office. In the absence of a specific ICD-10 code, cardiac sarcoidosis was defined as cases with sarcoidosis (ICD10: D86.0-8) in combination with heart disease (I41; I42; I44; I45; I46; I49; I50), excluding chronic coronary heart disease (I25). <bold>Results:</bold> Between 2010 and 2021, the prevalence of cardiac sarcoidosis increased from 0.05 to 0.20 per 100’000 inhabitants (p<0.001) whereas the proportion of cardiac sarcoidosis among all sarcoidosis cases significantly increased from 5% to 15% (p<0.001). Swiss-wide the prevalence significantly increased between 2010-2015 and 2016-2021 (incidence rate ratio: 2.1 [95% CI: 1.9-2.4]; p<0.001). The upward trend was more pronounced in the cantons of Geneva, Lucerne, Valais, Vaud and Zurich than in central Switzerland. The proportion of cardiac sarcoidosis cases receiving cardiac devices (ICD-10: Z95) increased from 15% to 30%, while in-hospital mortality initially decreased and then stabilized over time. <bold>Conclusion:</bold> In this retrospective nation-wide study, we found a significant increase in the prevalence and proportion of cardiac sarcoidosis from 2010 to 2021. The cantonal heterogeneity likely reflects heterogeneous awareness and access to cardiac imaging. The increased rate of cardiac device implantation paralleled a decreased in-hospital mortality.