The following are key points to remember from this state-of-the-art review on a multiparametric cardiovascular magnetic resonance (CMR) approach in diagnosing, monitoring, and prognostication of myocarditis:

1. CMR, as a technique that allows for noninvasive evaluation of myocardial function and tissue characteristics, is invaluable in establishing the diagnosis of myocarditis. Endomyocardial biopsy, historically seen as the gold standard for the diagnosis of myocarditis, is prone to false-negative results and is not recommended in any low-risk cases of suspected myocarditis.
2. Per the updated Lake Louise Criteria for CMR, published in 2018, the diagnosis of myocarditis requires ≥1 T1-based marker of nonischemic myocardial injury (abnormal T1 mapping, increased extracellular volume [ECV], or late gadolinium enhancement [LGE]) and one T2-based marker of myocardial edema (abnormal T2 mapping or regional abnormalities on T2-weighted imaging) (Ferreira VM, et al., J Am Coll Cardiol 2018;72:3158-76). Imaging criteria supportive of a diagnosis of myocarditis may include reduced left ventricular systolic function, regional wall motion abnormalities, and pericardial effusion. CMR-based global left ventricular strain and artificial intelligence techniques are under active investigation in the context of myocarditis.
3. Among clinical and imaging parameters, LGE is the strongest independent predictor of mortality in myocarditis, with hazard ratio 8.4 for all-cause mortality and 12.8 for cardiac mortality. The proportion of LGE relative to left ventricular mass is significantly associated with worse prognosis. Another CMR marker of adverse outcomes is ECV >35%.
4. Currently, there are no clear guidelines for long-term monitoring in patients with myocarditis. The authors propose follow-up CMR at 3 months following the diagnosis of acute myocarditis to assess for ongoing inflammation and to assess the extent of LGE. If LGE does not resolve in the long-term, it is indicative of scar. Particularly in athletes who wish to resume physical activity after acute myocarditis, serial CMR scans can be helpful in risk stratification, as a component of comprehensive clinical follow-up.

Clinical Topics: Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Pericardial Disease, Prevention, Sports and Exercise Cardiology, Acute Heart Failure, Chronic Heart Failure, Magnetic Resonance Imaging, Exercise, Sports and Exercise and Imaging

Keywords: Artificial Intelligence, Athletes, Biopsy, Contrast Media, Diagnostic Imaging, Edema, Cardiac, Exercise, Gadolinium, Heart Failure, Inflammation, Magnetic Resonance Imaging, Myocarditis, Pericardial Effusion, Risk Assessment, Secondary Prevention, Ventricular Function, Left

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