Risks and benefits of cardiac rehabilitation in patients after acute myocarditis
Viral myocarditis (MC) is a multifaceted disease entity characterized by a broad clinical spectrum ranging from oligosymptomatic abortive forms to fulminant MC including cardiogenic shock.1 A definite diagnosis may be difficult and a causal therapy is not yet established.2 Apart from clinical presentation, electrocardiogram (ECG) alterations, echocardiographic findings, and biomarkers the diagnosis of MC may further be affirmed by cardiac magnetic resonance imaging (CMR) as CMR provides a high sensitivity for detection of focal scars, myocardial inflammation, and oedema. Finally, the diagnostic confirmation including a reliable classification of MC can be obtained by endomyocardial biopsy (EMB). As gold standard technique EMB includes histological, immuno-histochemical, and molecular-genetic examinations, being essential tools for specific and individualized treatment strategies.
Although multicomponent cardiac rehabilitation (CR) is effectively used in patients after acute coronary syndrome and after cardiac surgery, there are no prospective studies that expand the evidence of CR also being clinically beneficial after acute MC.3 Case reports document a favourable course of the disease with CR even after fulminant acute MC.4 So far, there are reviews and position statements regarding the return to sports and disqualifying circumstances in competitive athletes with cardiomyopathies and MC.5,6 Data regarding return to work and recommendations for recreational activity in non-athletic MC patients are rare.
Even after stabilization of left ventricular function in formerly definitive or suspected MC the majority of patients suffers from prolonged exertional dyspnoea due to reduced peripheral muscular strength and possible subclinical myocardial inflammation. Moreover, patients with MC are at elevated risk for malignant ventricular tachyarrhythmias that might even be increased if physical exercise training is initiated too early and/or performed too intensively.7 The concern of persistent or paroxysmal clinically relevant arrhythmias therefore impedes a broad acceptance of CR in MC patients, and there is still uncertainty about the earliest time allowing initiation of physical training without risk of exercise-related sudden cardiac death (SCD). On the other hand, small and individually tailored physical activity already should start in hospital to prevent complications like thrombosis, muscular atrophy, and pulmonary infections and stepwise intensified in order to normalize and increase mobility, individual exercise capacity thereby also regaining quality of life.
Apart from these considerations, many of the MC patients exhibit prolonged or even persistent systolic left ventricular (LV) dysfunction and thereby representing a broadly accepted rehabilitation indication.8 In these patients CR enables a clinical and haemodynamic monitoring after the acute inpatient stay as well as an optimization of heart failure medication.9 A prolonged non-invasive rhythm evaluation (24–72 h Holter ECG) in parallel to the gradual increase of physical activity as well as supervised exercise stress tests (including cardiopulmonary exercise testing) enables a SCD risk stratification and the measurement of the global post-MC aerobic capacity. Serial echocardiographic investigations accompanied by biomarker analyses support the clinical estimation of the effects of physical strain. Thus, recommendations for leisure-time or sporting activities can be given on a more reliable basis. An individualized approach of professional reintegration, variable in terms of time and content, can be organized by the social services of the rehabilitation clinics through a work place analysis.
Based on the available evidence, the German, Swiss and Austrian Associations for Prevention and Rehabilitation of Cardiovascular Diseases (DGPR, SCPRS, ÖKG) have prepared a stratified approach to start CR as early as possible without neglecting the potential risks in patients with MC.10 Criteria to characterize the functional stages of MC patient in CR are summarized in Table 1.
Checklist of diagnostic tools in patients after MC during CR
| Diagnostic tool | Parameters |
|---|---|
| Clinical presentation and examination | NYHA classification, chest pain, clinical signs of infection, fatigue, palpitation, peripheral oedema, pulmonary rales, blood pressure, heart rate, body temperature, breathing frequency |
| Resting ECG | Heart rhythm disorders, conduction and repolarization disturbances |
| 24-h-Holter ECG (prolonged up to 72 h) | Inadequate sinus tachycardia or bradycardia, paroxysmal atrial fibrillation, high incidence of PAC or PVC, complex arrhythmias, intermittent bundle-branch-block, high-degree AV block, heart rate variabilitya |
| Biomarkers | Troponin, CK-MB, CRP, BNP or NT-pro BNPb |
| 2D-echocardiography | Internal dimensions, global and regional LV systolic function, diastolic LV function, global longitudinal strain, pericardial effusion |
| Exercise ECG | exercise-induced complex arrhythmias, exertional angina, myocardial ischaemia |
| CPX | VO2peak, VE/VCO2, VO2/HF |
| Diagnostic tool | Parameters |
|---|---|
| Clinical presentation and examination | NYHA classification, chest pain, clinical signs of infection, fatigue, palpitation, peripheral oedema, pulmonary rales, blood pressure, heart rate, body temperature, breathing frequency |
| Resting ECG | Heart rhythm disorders, conduction and repolarization disturbances |
| 24-h-Holter ECG (prolonged up to 72 h) | Inadequate sinus tachycardia or bradycardia, paroxysmal atrial fibrillation, high incidence of PAC or PVC, complex arrhythmias, intermittent bundle-branch-block, high-degree AV block, heart rate variabilitya |
| Biomarkers | Troponin, CK-MB, CRP, BNP or NT-pro BNPb |
| 2D-echocardiography | Internal dimensions, global and regional LV systolic function, diastolic LV function, global longitudinal strain, pericardial effusion |
| Exercise ECG | exercise-induced complex arrhythmias, exertional angina, myocardial ischaemia |
| CPX | VO2peak, VE/VCO2, VO2/HF |
Notes: a) the clinical relevance of arrthythmias and the course over the time needs to individually be judged taking into account all clinical and diagnostic parameters; b) all values above the upper limit (if ther is no other underlying disease), including serial measurements to evaluate/ascertain the healing process.
Checklist of diagnostic tools in patients after MC during CR
| Diagnostic tool | Parameters |
|---|---|
| Clinical presentation and examination | NYHA classification, chest pain, clinical signs of infection, fatigue, palpitation, peripheral oedema, pulmonary rales, blood pressure, heart rate, body temperature, breathing frequency |
| Resting ECG | Heart rhythm disorders, conduction and repolarization disturbances |
| 24-h-Holter ECG (prolonged up to 72 h) | Inadequate sinus tachycardia or bradycardia, paroxysmal atrial fibrillation, high incidence of PAC or PVC, complex arrhythmias, intermittent bundle-branch-block, high-degree AV block, heart rate variabilitya |
| Biomarkers | Troponin, CK-MB, CRP, BNP or NT-pro BNPb |
| 2D-echocardiography | Internal dimensions, global and regional LV systolic function, diastolic LV function, global longitudinal strain, pericardial effusion |
| Exercise ECG | exercise-induced complex arrhythmias, exertional angina, myocardial ischaemia |
| CPX | VO2peak, VE/VCO2, VO2/HF |
| Diagnostic tool | Parameters |
|---|---|
| Clinical presentation and examination | NYHA classification, chest pain, clinical signs of infection, fatigue, palpitation, peripheral oedema, pulmonary rales, blood pressure, heart rate, body temperature, breathing frequency |
| Resting ECG | Heart rhythm disorders, conduction and repolarization disturbances |
| 24-h-Holter ECG (prolonged up to 72 h) | Inadequate sinus tachycardia or bradycardia, paroxysmal atrial fibrillation, high incidence of PAC or PVC, complex arrhythmias, intermittent bundle-branch-block, high-degree AV block, heart rate variabilitya |
| Biomarkers | Troponin, CK-MB, CRP, BNP or NT-pro BNPb |
| 2D-echocardiography | Internal dimensions, global and regional LV systolic function, diastolic LV function, global longitudinal strain, pericardial effusion |
| Exercise ECG | exercise-induced complex arrhythmias, exertional angina, myocardial ischaemia |
| CPX | VO2peak, VE/VCO2, VO2/HF |
Notes: a) the clinical relevance of arrthythmias and the course over the time needs to individually be judged taking into account all clinical and diagnostic parameters; b) all values above the upper limit (if ther is no other underlying disease), including serial measurements to evaluate/ascertain the healing process.
Recommendations for cardiac rehabilitation delivery in patients recovering from acute myocarditis
Patients with ‘acute MC’ should not be transferred to CR. Although CMR/EMB is desirable to confirm the diagnosis, CR should even be avoided if there is high clinical suspicion of acute MC (typical clinical symptoms, increased biomarkers, pathological echocardiography). Physiotherapeutic activities should be focused on prevention of venous thrombosis, pulmonary infections, and accelerated muscular atrophy. Exercise training, however, is contraindicated because of the potential risk of prolongation/aggravation of myocardial inflammation, and increased morbidity and mortality.10–13
Patients with ‘healing MC’ and patients after MC (‘healed MC’) should be transferred to CR. ‘Healing MC’ can be assumed if clinical, laboratory and imaging findings demonstrate a course towards recovery, while ‘healed MC’ can be assumed if active myocardial inflammation has regressed completely (ideally documented by CMR).14 Before starting physical activity during CR, a non-invasive risk stratification is mandatory because ‘healing MC’ may still encompass persistent myocardial inflammation (‘subacute myocarditis’). Magnetic resonance imaging (CMR) is the most powerful cardiac imaging modality for detection and quantification of myocardial oedema, inflammation, necrosis and fibrosis. Contrast-enhanced CMR with gadolinium provide sensitive diagnostic information about LV fibrosis pattern, whereas particularly novel techniques of T1 and T2 mapping including extracellular volume quantification can be used for differentiation between acute/active and healed inflammation. In case of continuing inflammation an increased mortality is to be assumed and the CR should be postponed.15,16
Patients with clinically suspected MC but excluded by EMB or CMR should be transferred to CR, if there are remaining well accepted indications like myocardial dysfunction of other origin, cardiovascular disease, elevated cardiovascular risk etc. (Figure 1).
When and how to perform cardiac rehabilitation in individual stages of MC?
Patients with ‘healing myocarditis’
Characterization: inconspicuous clinical presentation, biomarkers in the normal range, resting ECG with normal or minimal residual alterations, 24 h Holter ECG without relevant arrhythmias, 2D echo: stabilized or increasing LV ejection fraction (LVEF) and no or diminishing pericardial effusion.
Symptom limited exercise test should not be performed.
Physical activity should be started with low intensity (Borg Scale 6–8/20 Received Perception of Exertion) increasing heart rate only little above resting value (Figure 2).
Prolonged ECG monitoring (72 h Holter ECG) should be performed.
Serial (weekly) investigation of clinical presentation, resting ECG, biomarkers, as well as 2D-echocardiography should be performed during CR.
Exercise training has to be stopped immediately, if any adverse signs are detected (worsening heart failure, increase of ventricular arrhythmias, or biomarkers or recurrent pericardial effusion).
Patients with ‘healed myocarditis’
Characterization: inconspicuous clinical presentation, biomarkers in the normal range, resting ECG with normal or minimal residual alterations, 24 h Holter ECG without relevant brady- or tachyarrhythmias, 2D echo: normal or slightly reduced LV function, no pericardial effusion, slightly enlarged left ventricle.
Symptom limited exercise test should be performed with caution.
Exercise testing or physical exercise to exhaustion should not be performed.
Residual signs in the resting ECG do not preclude a cautious increase in exercise intensity, if the patient exhibits normal LVEF without pericardial effusion, a normal Holter-ECG and normal laboratory testing.
Physical exercise should be started with low to moderate intensity (Borg Scale 10–12/20 Received Perception of Exertion (Figure 2).
In stable patients exercise intensity may be increased cautiously.
Exercise prescription in patients with persistent reduced systolic function should be tailored according to the Guidelines of exercise training in heart failure.17,18
Recommendations for exercise prescription in patients with coronary artery disease may not be transferred 1:1 in MC patients.
Individually adapted aerobic continuous and dynamic strength training seems reasonable and safe in patients with MC.
Serial (weekly) investigation of clinical presentation, resting ECG, biomarkers, as well as 2D-echocardiography should be performed during CR.
Exercise training has to be stopped immediately if any adverse signs are detected (see above).
Patients with initially suspected, but not verified MC in history
Characterization: symptomatic patients, but MC not verified by EMB or CMR, all test results are normal, objectively cardiac healthy patients, but with newly described and persistent symptoms (fatigue, palpitations and reduced exercise capacity).
Individual decision as to whether a CR is indicated at all.
Start a standard CR program without delay.
Serial investigation of clinical presentation, resting ECG, biomarkers, as well as 2D-echocardiography should be performed during CR.
Long-term follow-up
According to the European Society of Cardiology (ESC) recommendations in patients after definite or suspected MC moderate or high-intensity exercises including competitive sports should not be performed within 3–6 months after complete recovery, verified by CMR, biomarkers, and stress exercise testing.18
As the natural course of the MC is favourable in most cases19 the central goal should be the reintegration in the former social and occupational life. As a consequence, CR should be an integrated part in the trans-sectorial management of MC patients. Balancing reconditioning with a closely monitored clinical course the patients should be evaluated on a case by case basis. Further studies and multicentre prospective registries are needed to validate whether the proposed stratified approach is reasonable and safe in clinical practice of CR in MC patients. This is all the more important as the current COVID-19 pandemic might increase the prevalence of consecutive MC and the need for CR by specialized teams.20
Flow chart for the management of myocarditis patients.
Recommendations for the exercise level for patients with healing (A) and healed (B) myocarditis according to the BORG scale.
References
Author notes
Conflict of interest: none declared.
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