Abstract 4143614: Clinical Features and Prognosis of FDG-avid Genetic Cardiomyopathies

Introduction: Cardiac 18 FDG-PET is frequently utilized to noninvasively diagnose inflammatory cardiomyopathies such as cardiac sarcoidosis (CS). Many patients are diagnosed with presumptive isolated CS based on cardiac 18 FDG-avidity and the Japanese Circulation Society (JCS) guidelines. However, individuals with genetic cardiomyopathies present similarly to CS, are often 18 FDG-avid, and may be misdiagnosed with isolated CS. Aims: Determine the prevalence of pathogenic or likely pathogenic variants (P/LP) in patients with 18 FDG-avid cardiomyopathy and evaluate how 18 FDG avidity may impact prognosis. Methods: This is a single center, retrospective analysis of patients who had undergone both cardiac 18 FDG-PET and commercial genetic testing with a comprehensive cardiomyopathy panel (Invitae). Patients with biopsy-proven extracardiac or CS were excluded. Group comparisons made using Chi-square. The composite endpoint of cardiac mortality, sustained VT, LVAD, heart transplant, and heart failure hospitalization was compared between groups using Cox Proportional Hazard’s Model. Results: Of 128 patients with both cardiac 18 FDG-PET and genetic testing, 112 patients (30% women; mean age 56) met our inclusion criteria. 18 FDG-avidity was present in 54 (48%), of which 9 (17%) had P/LP ([list genes here]). Of these 9, 5 (56%) met JCS diagnostic criteria for isolated CS, 4 were clinically diagnosed with CS, and 2 had been immunosuppressed prior to their genetic testing results. Baseline characteristics were similar between 18 FDG-avid and 18 FDG-negative patients with genetic cardiomyopathies (Figure 1). P/LP prevalence was significantly higher in the 18 FDG-negative group (13, 22%, p=0.01). LP/P variants were most commonly found in LMNA (n=10). Among patients with genetic cardiomyopathy, there was no significant difference in the composite endpoint between 18 FDG-avid and FDG-negative groups (Figure 1; HR 2.3 (95% CI: 0.7-7.2, p-value 0.17). Conclusions: Genetic cardiomyopathies are often mis-diagnosed as isolated CS based on 18 FDG-avidity, and genetic testing should be performed prior to diagnosing isolated CS. Larger, multi-center studies are needed to determine if 18 FDG-avidity predicts prognosis in genetic cardiomyopathies.