From the Guidelines
Myocarditis diagnosis should be based on a combination of clinical presentation, laboratory tests, and imaging studies, with cardiac MRI being the gold standard non-invasive diagnostic tool, as recommended by the 2022 ACC expert consensus decision pathway 1. The diagnostic approach begins with evaluating symptoms such as chest pain, shortness of breath, fatigue, and palpitations, along with a thorough medical history.
- Blood tests are essential, particularly cardiac biomarkers like troponin, which are typically elevated in myocarditis, as stated in the 2022 ACC expert consensus decision pathway 1.
- Inflammatory markers including ESR and CRP may also be increased.
- Electrocardiogram (ECG) often shows nonspecific ST-segment and T-wave abnormalities, while echocardiography can reveal ventricular dysfunction or wall motion abnormalities.
- Cardiac MRI is now considered the gold standard non-invasive diagnostic tool, as it can detect myocardial inflammation, edema, and fibrosis using techniques like T1 and T2 mapping and late gadolinium enhancement, as supported by the 2018 expert recommendations on cardiovascular magnetic resonance in nonischemic myocardial inflammation 1. In cases where diagnosis remains uncertain, endomyocardial biopsy may be performed, though it's typically reserved for severe or treatment-resistant cases due to its invasive nature.
- The Dallas criteria, which evaluate histopathological findings of inflammatory infiltrates and myocyte damage, are used to interpret biopsy results. Early diagnosis is crucial as it guides appropriate treatment strategies and helps prevent long-term cardiac complications, with hospitalization recommended for patients with definite myocarditis that is either mild or moderate in severity, ideally at an advanced heart failure center, as recommended by the 2022 ACC expert consensus decision pathway 1.
From the Research
Myocarditis Diagnosis
- Myocarditis is an underdiagnosed condition that affects people of all ages and can be asymptomatic or present with a variety of symptoms 2.
- The diagnosis of myocarditis can be challenging due to varied clinical features that sometimes overlap with other cardiac conditions, requiring a high index of suspicion and appropriate diagnostic methods for timely detection 2, 3.
- Laboratory assessment, electrocardiogram, and echocardiography can be helpful for the diagnosis, with cardiac magnetic resonance imaging or endomyocardial biopsy required for definitive diagnosis 3, 4.
Diagnostic Modalities
- Initial workup for myocarditis includes laboratory tests, electrocardiogram, and echocardiography 3.
- Cardiac magnetic resonance imaging is considered the gold standard noninvasive diagnostic method for myocarditis 2, 4.
- Endomyocardial biopsy is an invasive technique that can provide definitive diagnosis of myocarditis 2, 4.
Clinical Presentation
- Symptoms of myocarditis can range from mild to severe and are often preceded by a viral prodrome 3.
- Approximately 82% to 95% of adult patients with acute myocarditis present with chest pain, while 19% to 49% present with dyspnea, and 5% to 7% with syncope 4.
- Elevated biomarkers such as troponins, electrocardiographic changes of ST segments, and echocardiographic wall motion abnormalities or wall thickening can suggest the diagnosis of myocarditis 4.