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.......................................................................................................................................................................... 5.5.5.2 Diagnosis Serum cardiac troponin is usually elevated in myopericarditis and is a sensitive marker of cardiac inflammation-induced myocyte necrosis.435

The ECG has low sensitivity and electrical anomalies are nonspecific. ECG patterns vary from non-specific T-wave and STchanges to ST-segment elevation mimicking MI, left bundle branch block (LBBB), or frequent and/or complex ventricular and supraventricular arrhythmias, or atrioventricular block, or low QRS voltages in the presence of a pericardial effusion.436 Recognized echocardiographic features of overt myocarditis include a non-dilated LV cavity with increased myocardial wall thickness (when oedema is present), or mildly dilated LV cavity with a thinned myocardial wall, usually with regional wall motion abnormalities.437 The global LV systolic function may range from being almost normal to severely depressed. Regional wall motion abnormalities may be present.438 CMR is the most useful diagnostic tool and has excellent sensitivity for detecting myocardial hyperaemia, inflammation, oedema and/or focal scar.439,440 The Lake Louise Criteria and LGE are now complemented by CMR techniques of T1/T2 mapping and extracellular volume fraction (ECV).440442 The extent and distribution of LGE with non-ischaemic pattern are independent predictors of CV events during follow-up.439,440,443447 Namely, a 10% increase of LGE volume conveys a 79% increase in the risk of major CV events.448,449 Endomyocardial biopsy is the gold standard for the diagnosis of myocarditis.450,451 A histological diagnosis allows distinction between the different types of inflammatory processes, (i.e. giant cell myocarditis), and guides treatment in life-threatening presentations.430,445,452 The diagnostic yield of endomyocardial biopsy can be improved by analysing the viral genome through DNA- RNA extraction and reverse transcriptase polymerase chain reaction (RT-PCR) amplification, which has the advantage of identifying the disease-causing pathogen.445

5.5.5.3 Risk stratification Case series have established myocarditis as a risk factor for SCD, which accounts for up to 220% of sudden death in athletes.17,18,28,430,453,454 Murine models have shown that daily exercise in mice infected with Coxsackie virus is associated with increased viral titres, fulminant myocarditis, and sudden death.455 These animal models provide some insight into the mechanisms of SCD with exercise, which appears to cause an accelerated and progressive inflammatory response.455458

5.5.5.4 Exercise recommendations for individuals with myocarditis Athletic individuals with a probable or definitive diagnosis of recent myocarditis should be advised to abstain from competitive sports or leisure sports while active inflammation is present, regardless of age, sex, or extent of LV systolic dysfunction.459,460 The duration of myocardial inflammation can be highly variable and may take several months for full resolution. Both the ESC and AHA recommend abstinence from moderate- to high-intensity exercise for a period of 36 months,459,460 although the precise timing for return to competitive or recreational sports involving moderate- or high-intensity exercise may be guided by the presence of inflammation on T2-weighted images and LGE uptake on CMR.3,461

Individuals with myocarditis should have a comprehensive evaluation after complete recovery to assess the risk of exercise-related SCD. Imaging studies, exercise stress test, and Holter monitor provide essential information for risk stratification. Depressed LV function, presence of LGE and complex VAs during exercise or Holter monitoring are recognized risk markers for adverse outcomes.455,462,463 Repeat evaluation should consist of measurement of troponin and biomarkers of inflammation, echocardiography, and prolonged ECG monitoring. Individuals without evidence of ongoing inflammation should undergo an exercise stress test. A CMR should be repeated if myocardial oedema or LGE was present during the acute illness. Return to sporting activities should be considered, in asymptomatic individuals, with normal troponin and biomarkers of inflammation, normal LV systolic function on echocardiography and CMR, no evidence of ongoing inflammation or myocardial fibrosis on CMR, good functional capacity, and absence of complex arrhythmias during exercise on prolonged ECG monitoring .430,434,453,459,460,464 Individuals with previous myocarditis are at risk of recurrence and silent clinical progression, and the presence of LGE during the acute presentation is associated with increased incidence of major adverse cardiac events; therefore, periodic re-evaluation is advised on an annual basis.443,445,454,463 Among individuals with healed myocarditis with persistence of LGE on CMR but no myocardial oedema at 36 months, those who are asymptomatic, with normal troponin and biomarkers of inflammation, normal LV systolic function, no evidence of ongoing inflammation on CMR, and absence of complex arrhythmias during exercise on prolonged ECG monitoring (48 h Holter ECG and exercise stress testing), should be evaluated on a case by case basis and may return to competitive sports on an individual basis. In contrast, individuals with extensive myocardial scar (>20% LGE) and persistent LV dysfunction should abstain from exercise programmes and sports activities involving moderate or high physical intensity.

5.5.6 Pericarditis Pericarditis is defined as an inflammatory disorder of the pericardium,430,465 which may be preceded by upper respiratory or gastrointestinal symptoms. As with myocarditis, viral pathogens are the most commonly implicated pathogens in the western world.

5.5.6.1 Diagnosis The ECG is non-specific but may reveal characteristic concave STsegment elevation in most leads and/or PQ depression in the acute phase. Echocardiography may reveal a pericardial effusion. CMR should be considered in individuals with raised cardiac troponin levels to assess for concomitant myocardial inflammation. Furthermore, CMR will identify active inflammation of the pericardium, thickened pericardial layers, and any signs of pericardial constriction.

5.5.6.2 Risk stratification Pericarditis is generally associated with an excellent prognosis.430,465,466 However, there are a subset of patients who may be at greater risk of recurrence and these include individuals with a temperature >38C at Downloaded from academic.oup.com/eurheartj/article/42/1/17/5898937 by guest on 07 October 2026