Muscle pathology – proposed algorithm
October 17, 2026Muscle pathology – Patient stable
October 17, 2026Myocarditis algorithm – Unstable patient
Fulminant suspected myocarditis
Immediate actions
- Transfer to ICU; urgent cardio-oncology/cardiology advice
- Withhold ICI pending final diagnosis
- Start prednisone equivalent 2 mg/kg OR methylprednisolone 1,000 mg/day for 1–3 days within 24 h
- Reassess Troponin levels after +/- 6, 12, 24 and 36h
- Consider ruxolitinib or MMF
Diagnostic confirmation (IC-OS criteria) ?
- Perform CMR and/or endomyocardial biopsy
- Perform Coronary angiography to exclude ACS
Diagnostic criterium
- Histological diagnosis
OR
- Clinical diagnosis (Troponin elevation AND 1 major criteria OR 3 minor criteria)
- Major criteria: positive MRI (Lake Louise criteria)
- Minor criteria
- Cardiomuscular symptoms
- Ventricular arrythmia or new conduction block
- Decline in LVEF
- Presence of myositis or other irAE
- suggestive MRI
No = No myocarditis
- Stop steroids
- Discuss rechallenge individually
Yes = Confirmed myocarditis
- Permanently discontinue ICI
- Slow taper of steroids (5-10mg/week) and follow up of CK, Troponin T or I within 12-24h.
- No rechallenge
Follow-up
No improvement
- No clinical or troponin response in 48h
- Consider abatacept + ruxolitinib, especially if respiratory failure from diaphragmatic myositis
- Tocilizumab, IVIG, plasma exchange or other IS: discuss case by case
* There is no reimbursement for ruxolitinib or tocilizumab in this indication but sample programs are available. There is no reimbursement for IgIV in this indication in Belgium.
Improvement
- Taper steroids slowly (5–10 mg/week); monitor CK and troponin I or T every 12–24 h.