Coexistence of cardiac sarcoidosis and genetic cardiomyopathies: a conundrum

Abstract

Abstract Introduction Cardiac sarcoidosis (CS) is a chronic inflammatory disease characterized histologically by the formation of non-caseating granuloma in the myocardium, however, causes remain largely unknown. Genetic arrhythmogenic cardiomyopathy (ACM) is an important differential diagnosis of CS. Until now, few data are available about the coexistence of CS in a patient with genetic ACM harboring a desmoglein-2 (DSG2) variant. Purpose We report a case series of patients who demonstrate coexistence of histologically proven CS and genetic ACM. Methods This is a multicentric study, which included patients from four high-volume cardiology referral centres for heart failure and ACM in Switzerland, Italy, and Austria. Patients with both a biopsy-proven diagnosis of sarcoidosis with cardiac involvement (according to the 2014 HRS criteria) also harboring a pathogenic/likely pathogenic (P/LP) variant for cardiomyopathy-associated genes were 1:1 matched for age, gender and genetic variant with patients with genetic ACM without CS (Gen-only). Clinical and imaging data (echocardiography (TTE), cardiac magnetic resonance (CMR) and positron-emission tomography (18FFDG-PET/CT) were collected. Results Each group included 5 patients (Gen+CS: age 48 ± 11 years, Gen only: age 52 ± 13.7 years, n=3 (60%) female in both groups). For each group, the following genes with P/LP variants were found: PKP2: n=2 (40%), DSG2: n=1 (20%), DSP: n=1 (20%), TTN: n=1 (20%). In patients with Gen+CS, atrio-ventricular block (AVB) I° (80% vs 20%, p=0.05) and paroxysmal atrial fibrillation (80% vs 0%, p=0.004) were more frequent, and median NT-proBNP levels (1346ng/l, IQR:103-4276 vs. 214ng/l, IQR:131-326, p=0.046), as well as high-sensitive C-reactive protein levels were higher (3.1g/dl, IQR:1.1-24.2 vs. 0.7g/dl, IQR:0.3-0.95, p=0.016). On imaging, Gen+CS patients were more likely to have septal involvement (60% vs 0%, p=0.021), as highlighted by positive late-gadolinium enhancement on CMR, metabolic activity on PET, or focal wall motion anomalies on TTE. Conclusions CS and genetic ACM can coexist. Hence, detection of a P/LP genetic variant associated with ACM should not lead to exclusion of CS, which more frequently presents with AVB, septal involvement, heart failure, and metabolic activity on imaging. On the contrary, CS can be associated with genetic variants in cardiomyopathy-associated genes.FDG-PET/CT