Abstract Body (Do not enter title and authors here): Introduction: Cardiac ¹⁸FDG-PET is an imaging modality frequently used to diagnose inflammatory cardiomyopathies such as cardiac sarcoidosis. Japanese Circulation Society (JCS) guidelines propose a set of criteria for non-invasively diagnosing isolated cardiac sarcoidosis using ¹⁸FDG-PET. Recent data suggests that many patients with ¹⁸FDG-avid PET have genetic cardiomyopathies. We hypothesize that ¹⁸FDG -avidity may be a marker of inflammation or metabolic dysregulation which is pro-arrhythmic.
Objectives: To compare the clinical presentation and prevalence of pathogenic variants in patients with and without ¹⁸FDG -avidity and to determine whether ¹⁸FDG -avidity predicts VT/VF free survival.
Methods: A retrospective cohort study utilizing patients from University of Washington and Oregon Health Science University who underwent ¹⁸FDG -PET and had genetic testing through Invitae. Patients with biopsy proven sarcoidosis were excluded. Chi-square statistical testing was used to compare groups and Cox-regression was used to assess survival free from the composite endpoint of VT/VF or mortality.
Results: A total of 202 patients with genetic testing and ¹⁸FDG -PET were identified across 2 institutions yielding 100 patients with ¹⁸FDG -avidity and 102 patients with ¹⁸FDG -negative PET. A total of 35 patients had pathogenic or likely pathogenic (P/LP) genetic variants, 37% of whom were ¹⁸FDG -avid (Figure 1; P-value 0.1). Patient demographics and presenting clinical features were similar between ¹⁸FDG -avid and ¹⁸FDG -negative patients (Table 1). P/LP variants (¹⁸FDG -avid, ¹⁸FDG -negative) include DSP (1,4), FLNC (1,1), LMNA (3,8), MYBPC3 (1,0), MYH7 (1,2), TTN (5,4). Of the 100 ¹⁸FDG -avid patients, 51% met JCS criteria for isolated cardiac sarcoidosis and 14% (n=7) of ¹⁸FDG -avid patients meeting JSC criteria had P/LP variants. In Cox regression analysis, VT/VF free survival was similar between ¹⁸FDG -avid patients with and without P/LP variants and ¹⁸FDG -negative patients with and without LP/P variants (p=0.26). ¹⁸FDG-avid patients had similar VT/VF free survival to ¹⁸FDG-negative patients (p=0.21).
Conclusion: There was a similar prevalence of P/LP variants amongst patients with and without ¹⁸FDG -avidity. JCS criteria was commonly met by patients with ¹⁸FDG -avidity and amongst ¹⁸FDG -avid patients with P/LP variants suggesting a lack of specificity for isolated cardiac sarcoidosis. Cardiac FDG-avidity was not associated with increased VT/VF/mortality.