Abstract Body (Do not enter title and authors here): Background

Cardiac sarcoidosis is a cardiomyopathy associated with a high risk of ventricular arrhythmias and heart failure. Autopsy studies of patients with systemic sarcoidosis but no macroscopic cardiac involvement have identified cardiac sarcoidosis granulomas on histological examination. However, the clinical significance of granuloma-only cardiac involvement in living patients with sarcoidosis remains unclear.

Research Question

We aimed to determine the prevalence and clinical implications of granuloma-only cardiac involvement among patients with sarcoidosis.

Methods

We analyzed consecutive patients with histology-supported sarcoidosis who underwent cardiovascular magnetic resonance imaging (CMR) and had cardiac tissue sampling between 2004 and 2023 at two centers.

Results

Among 1,500 patients, 86 (5.7%) had cardiac tissue sampling for clinical indications; of these, 31 did not have CMR features of cardiac sarcoidosis. Among these 31 patients, 4 (12.9%) had sarcoidosis granulomas detected in cardiac tissue. None exhibited clinical or CMR features specific for cardiac sarcoidosis either at presentation or during follow-up.

Conclusions

Granuloma-only cardiac involvement was observed in 13% of patients with sarcoidosis who underwent cardiac tissue sampling for clinical indications. The granulomas were not associated with clinical or CMR evidence of cardiac sarcoidosis cardiomyopathy, indicating they were incidental. Our findings challenge the traditional classification of “subclinical” cardiac sarcoidosis, as these granulomas did not progress to clinically relevant disease. Therefore, our findings suggest avoiding the diagnosis of cardiac sarcoidosis cardiomyopathy in patients with incidental granulomas and excluding them from prevalence estimates for this condition. Further research is needed to investigate the long-term implications of incidental cardiac sarcoidosis granulomas and their role in individuals predisposed to genetic cardiomyopathy.