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4.2.2 Fulminant myocarditis

Fulminant myocarditis (occurring in 3%–9%) is characterized by cardiogenic shock at presentation for which haemodynamic support is needed.28 Isolated right ventricle (RV) dysfunction is uncommon; however, biventricular failure occurs frequently in FM. Sustained ventricular arrhythmias (VA) may also occur in these patients (46.9%) and some present with sudden cardiac death (SCD) (25.8%).28,56,57 In the majority of children with FM (usually <2 years of age), LV dysfunction with dilatation is present at initial presentation,40 while there is usually no LV dilatation in the early phase for adults. Concurrent viral infections can be common in these children.

4.2.3 Subacute myocarditis

The subacute stage refers to cases with symptoms lasting >1 month but ≤3 months. The symptoms are unspecific, and patients might either have a remission without residuals or might progress to chronic myocarditis or inflammatory CMP (see Section 10).

4.2.4 Chronic myocarditis

Chronic myocarditis is myocarditis persisting beyond 3 months.39 Chronic myocarditis might reflect an intermediate stage possibly leading to inflammatory CMP, characterized by cardiac remodelling and some degree of ventricular dysfunction.10,39

Milder forms may appear as hypokinetic non-dilated forms of CMP.39 Moreover, an arrhythmogenic substrate, due to fibrosis, should be considered for the management of these patients.39,58

Symptoms may be unremarkable in chronic myocarditis.10,39 Dyspnoea and palpitations might be the leading symptoms.10,39 Biomarkers of myocardial injury are usually within normal limits.59 Notably, elevated C-reactive protein, hs-TnT, and impaired global longitudinal strain (GLS) have been associated with EMB-proven myocardial inflammation in patients with non-ischaemic HF.60 New quantitative CMR techniques have improved the diagnostic yield in patients with chronic myocarditis.61

4.3 Clinical presentations of myocarditis

Myocarditis is characterized by the heterogeneity of clinical manifestations (Figure 8); therefore, the diagnosis requires a high level of suspicion. The main patterns of clinical presentation are infarct-like chest pain (most frequent symptom), arrhythmias, and HF. Severity may range from asymptomatic/oligosymptomatic to severe life-threatening scenarios, such as severe HF or VA (potentially leading to SCD). A clinical classification based on presentation as high-risk or non-high-risk myocarditis (see Table 7) has been shown to meaningfully predict outcomes in large cohorts.28,62,63 Moreover, myocarditis, especially when recurrent, may represent the ‘hot phase’ of some CMPs [e.g. desmoplakin (DSP)-related ARVC].64 Details are given in Section 4.3.5.

4.3.1 Chest pain presentation

Chest pain is the most common form of clinical presentation (about 75% of unselected cases) in adolescents and adults.28 It is commonly associated with an increase in necrosis biomarkers, such as troponin, often with ECG alterations (especially ST-segment elevation), which may mimic ACS, despite the absence of significant obstructive coronary artery disease (CAD). These cases are often labelled as infarct-like.65 Patients with this presentation usually report a recent or concomitant viral infection, such as a respiratory tract infection or gastroenteritis, which often precedes myocarditis by several days to weeks (2–4 weeks). Usually, the presence of troponin release in the context of IMPS is not a negative prognostic marker, when associated with preserved biventricular function.4,66 Patients presenting with chest pain and normal left ventricular ejection fraction (LVEF) without wall motion abnormalities (WMA), no VA, and complete resolution of ECG abnormalities in the short term can



 

 



	   



 


  

 









Figure 8 Spectrum of myocarditis presentations and outcomes. LGE, late gadolinium enhancement; SCD, sudden cardiac death. Image size correlates with presentation frequency (e.g. chest pain being the most common). Uncomplicated cases of myocarditis (about 75% of unselected cases) usually have spontaneous remission.28 In acute myocarditis diagnosed by endomyocardial biopsy, up to 50% of patients have spontaneous recovery, but up to 25% may have a persistent stable cardiac dysfunction, while 10%–25% have a progressive ventricular dysfunction, which could lead to end-stage dilated cardiomyopathy, heart transplantation, or death.9

ESC Guidelines                                                                                                                                                                                          3971

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