Cardiac amyloidosis (CA) is the most common cause of death among patients with systemic amyloidosis [1]. CA primarily results from two forms of precursor proteins: transthyretin-derived amyloid (ATTR) and immunoglobulin light chain-derived amyloid [2]. ATTR-CA has been identified as a potential contributor to sudden cardiac death (SCD) in older adults [3]. Furthermore, we previously reported that sporadic ATTR (sATTR) amyloidosis patients could be a risk for SCD, even from an early phase [4]. ATTR-CA is gaining increasing clinical importance, as evidenced by the rapid rise in diagnostic frequency following the approval of tafamidis and technetium scintigraphy [5]. Therefore, a deeper understanding of potential risk factors for SCD in patients with ATTR-CA is crucial for establishing preventive strategies.

Sarcoidosis is an idiopathic granulomatous inflammatory disease. Sarcoidosis can affect various organs; however, the fatality of cardiac sarcoidosis (CS) emphasizes the importance of an accurate diagnosis in the prevention of arrhythmia-induced SCD [6]. CS can mimic various forms of cardiomyopathy at different stages, including CA [7,8]. A case of CS combined with ATTR-CA was recently reported [9]. This combination raises concerns about an increased risk of SCD. It is also hypothesized that ATTR deposits may trigger the development of sarcoidosis in the elderly. However, no histopathologic studies have sought to determine the frequencies of the two diseases and evaluate the association between them in a large autopsy cohort with many SCD cases.

To elucidate this, we examined a series of cases of sATTR amyloidosis and sarcoidosis identified via histopathology in our laboratory to determine if there are cases in which sATTR amyloidosis and sarcoidosis simultaneously occur and whether ATTR deposition can induce granulomatous inflammation consistent with sarcoidosis.