16 March 2026
: Case report 
Fatal Cardiomyopathy Secondary to Seronegative Immune-Mediated Necrotizing Myopathy: A Case Report
Challenging differential diagnosis, Rare disease, Rare coexistence of disease or pathology
Benjamin D. Lueck ABCDEF 1, Alyssa K.W. Maclean ABCDEF 1, Georges El Hasbani ABCDEF 2, Andrew J. Layman CDE 3, Floranne C. Ernste CDEF 2, Courtney A. Arment ABCDEFG 2*DOI: 10.12659/AJCR.951603
Am J Case Rep 2026; 27:e951603
Table 2 Summary of published cases, findings, treatments, and outcomes of patients with seronegative immune-mediated necrotizing myopathy (IMNM) and cardiac involvement.
| Study | Number of patients | Cardiac involvement | Treatment | Outcome |
|---|---|---|---|---|
| Tamura et al []12 | 1 | Fibrosis, reduced left ventricular ejection fraction, ventricular fibrillation | Glucocorticoids | Expired |
| Tsang et al [] and Malladi et al []13 | 1* | Reduced left ventricular ejection fraction, myocarditis, cardiogenic shock | Glucocorticoids, rituximab, intravenous immunoglobulin (IVIG) | Recovery |
| Sanchez et al []15 | 1 | Myocarditis, fibrosis, trifasicular block and ventricular tachycardia, sudden cardiac death | Glucocorticoids, mycophenolate, IVIG | Expired |
| Liu et al []9 | 13 | 6/13 Patients with cardiac involvement; myocardial ischemia (3) or infarction (2), left atrial dilation (1), impaired left ventricular diastolic function (1), pericardial effusion (1) | Not reported | Not reported |
| Triplett et al []10 | 58 | Majority of patients with abnormalities on electrocardiogram or echocardiogram; left ventricular diastolic dysfunction (50%), QTc prolongation (38%), conduction block (21%), left ventricular systolic dysfunction (6%) | Not reported | Echocardiogram repeated after treatment in 11 IMNM patients; 4 had improved diastolic function and 3 had improved systolic function** |
| Ma et al []11 | 16 | 11/16 patients with cardiac involvement; focal fibrosis (6), fascicular (1) or atrioventricular block (1), ventricular (2) or atrial (1) dilatation, left ventricular systolic dysfunction (1), myocardial ischemia (2), pericardial effusion (2) | Glucocorticoids (all patients, monotherapy for 4); plus tacrolimus (4), methotrexate (1), azathioprine (1), IVIG (1) | Marked improvement in strength (9), moderate improvement (2), subsequent dilated cardiomyopathy and heart failure (1) |
| Reported from retrospective analysis, clinical outcomes otherwise not available. All patients with immune-mediated necrotizing myopathy, not specifically seronegative. * Both sources refer to the same patient; ** all patients with immune-mediated necrotizing myopathy, not specifically seronegative. | ||||