Additional investigations to consider in patients with suspected myocarditis
| Investigation | Particular instance(s) to consider the investigation (although testing should not necessarily be limited to these specific situations) |
|---|---|
| Thyroid function tests | Clinical features suggestive of hyperthyroidism |
| Serum angiotensin converting enzyme level | Suspicion of sarcoidosis |
| Drug screen | Suspicion of myocarditis secondary to illicit drug use |
| Plasma and 24-hour urine metanephrines | Fulminant myocarditis/cardiogenic shock (phaeochromocytoma can cause a catecholamine-mediated myocarditis) |
| Nasopharyngeal swab for respiratory viruses PCR including influenza, SARS-CoV-2, adenoviruses and enteroviruses | History of a possible recent viral illness |
| ASO titre and throat swab for bacterial culture | Possible current/recent streptococcal infection |
| Testing for Mycoplasma pneumoniae (by PCR ± serology) | Current/recent atypical pneumonia |
| Blood borne virus screen, ie HIV, HBV and HCV serology | Identifiable risk factors, eg injecting drug use and/or abnormal liver function tests |
| Blood for EBV, CMV and parvovirus B19 serology | Recent glandular fever-like illness and/or rash |
| Autoantibodies (ANA initially and then possible further autoantibody screening guided by the clinical picture) | Suspicion and/or family history of an autoimmune/inflammatory condition |
| Urine analysis with urinary sediment (to look for casts/crystals/cells) | Abnormal renal function and/or suspicion of an inflammatory condition with renal involvement, eg lupus nephritis |
| Borrelia serology | Suspicion of Lyme disease, eg recent erythema migrans rash/recent tick bite/recent visit to a forest/grassy area |
| FDG-PET | When CMR is contraindicated or inconclusive and in suspected sarcoidosis (to detect active myocardial inflammation/potentially identify extra-cardiac features of sarcoidosis/identify sites amenable to biopsy) |
| Endomyocardial biopsy | Specific cases where deemed by a cardiologist/multi-disciplinary team likely to impact on patient management |
ANA = antinuclear antibody; ASO = antistreptolysin O; CMR = cardiovascular magnetic resonance imaging; CMV = cytomegalovirus; EBV = Epstein–Barr virus; FDG-PET = fluorodeoxyglucose-positron emission tomography; HBV = hepatitis B virus; HCV = hepatitis C virus; PCR = polymerase chain reaction; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2.