Elevated Troponin-I in association with autoimmune cardiomyopathy: Always a marker of cardiac damage?

Troponin I (cTnI) is widely used for the diagnosis of cardiac damage as it is the most sensitive and specific biomarker for cardiomyocyte injury. Herein we present a case of a young patient with autoimmune cardiomyopathy and persistently elevated serum levels of cardiac Troponin-I (cTnI) despite several months of treatment and escalating immunosuppressive regimens. Given her underlying immune disease there was concern that this may be a false - positive test resulting from the presence of circulating human anti-mouse antibodies (HAMA), which crosslink the antibodies used for the troponin ELISA and lead to a false positive result. Surprisingly, removal of HAMA antibodies from our patient's serum did not reverse her positive test. Instead, additional testing revealed that she had anti-cTnI antibodies in her circulation that stabilized cTnI, leading to persistent elevations of this biomarker using multiple cTcI diagnostic platforms. This case illustrates the importance of considering other mechanisms of cardiac biomarker elevation, particularly when the results are not consistent with the clinical disease.