Cardiac involvement and anti-striational antibodies in immune-mediated necrotizing myopathy.

Immune-mediated necrotizing myopathy (IMNM) is accompanied by extramuscular manifestations including cardiac complications, and such cardiac complications have a serious prognostic impact on these patients. This study aims to investigate cardiac manifestations and the presence of anti-striational antibodies in patients with IMNM. We retrospectively analyzed 13 patients diagnosed with IMNM and measured anti-striational antibodies. We also reviewed the literature on cardiac involvement in patients with IMNM. In the present study, all patients had elevated serum troponin T levels, and 76.9 % of the cases had electrocardiographic or echocardiographic manifestations. Three patients (23.1 %) developed acute heart failure during the course of the study; one patient died. Anti-Kv1.4 antibodies were positive in 10 patients (83.3 %), and in addition to anti-Kv1.4 antibodies, anti-titin antibodies were detected in one fatal case. Our literature review also showed that cardiac involvement is common in IMNM, with arrhythmias and left ventricular diastolic dysfunction as the main findings. Hence, cardiac involvement in IMNM may be more frequent than generally recognized, and perhaps this extramuscular manifestation should be carefully monitored. Anti-striational antibodies, particularly anti-Kv1.4 antibodies, may be potential biomarkers of inflammatory cardiomyopathy associated with IMNM, and the presence of anti-striational antibodies may have a prognostic impact on patients' outcomes.