Australian Doctor Australian Doctor 7th July 2017

How to Treat – Myocarditis Clinical presentation THE clinical manifestations vary widely, ranging from the patient being asymptomatic to life-threat- ening events. The symptoms include fatigue, reduced exercise tolerance, chest pain, palpitations, syncope and heart failure. Symptoms of an infectious viral prodrome with res- piratory or gastrointestinal symp- toms frequently precede the onset of the disease. 6 Chest pain is usually acute and is the initial presentation. It is often described as sharp or stabbing over the precordium and might be pleuritic. The pain may be relieved when the patient sits up and/or leans forward, as there may be a coexisting pericarditis (See previ- ous How to Treat on Pericarditis, 28 June 2013). The pain may also mimic the pain of acute coronary syndrome, myocardial ischaemia or MI. Sus- pect myocarditis when the chest pain is accompanied by abnormal ECG findings that present beyond a single vascular distribution and there is a paucity of traditional THE CLINICAL MANIFESTATIONS VARY WIDELY, RANGING FROM THE PATIENT BEING ASYMPTOMATIC TO LIFE-THREATENING EVENTS. The presence of palpitations is not uncommon in patients with myocarditis. Presyncope or syn- cope may be a signal for serious arrhythmias. Myocarditis can pro- duce variable effects on the cardiac conduction system and is responsi- ble for up to 20% of sudden car- diac deaths in young adults. 18 In patients with acute or chronic myocarditis, arrhythmia may be the only clinical symptom. The occurrence of conduction dis- turbances as well as serious ven- tricular arrhythmias should raise suspicion for more specific causes of myocarditis, such as Lyme dis- ease, Chagas disease, giant-cell myocarditis or cardiac sarcoido- sis. Factors responsible for the increased incidence of arrhythmias include structural changes, ven- tricular haemodynamics and vas- cular changes. 19 Acute inflammation of the car- diac myocytes and interstitium can lead directly to fluctuations in membrane potential, resulting in arrythmogenesis. In the later stages, fibrosis and scarring of the risk factors for accelerated athero- sclerosis, particularly in younger patients. Heart failure may develop early in a subset of patients with fatigue and decreased exercise capacity as the initial manifestations. If there is predominantly left ventricular involvement, patients present with features of pulmonary congestion, such as dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea and basal inspiratory crackles, as well as in severe cases, acute pul- monary oedema. Signs of right ventricular failure include elevated jugular venous pressure, hepa- tomegaly, ascites and peripheral oedema. In the chronic stage, years after an initial index event of myocardi- tis, most patients have dilated car- diomyopathy, which places them at a greater risk of developing heart failure. In some cases, heart failure may develop as a result of subclinical viral myocarditis. Severe myocarditis, if rapid in evo- lution, can result in acute heart failure and cardiogenic shock. myocardium are responsible for electric remodelling that can pro- vide a substrate for arrhythmia. 20 Acute myocarditis is mainly a self-limiting illness, with spontane- ous complete resolution. However, in some instances, the condition may evolve and progress into dilated cardiomyopathy with left ventricular systolic dysfunction, or sudden death due to arrhythmia. Fulminant myocarditis is a dis- tinct entity, characterised by severe haemodynamic compromise, car- diogenic shock or fatal arrhythmia at presentation, but paradoxically, it has an excellent long-term sur- vival. 21 In the majority of patients, there is complete resolution of the dis- ease, but myocarditis has been observed to recur in a similar sce- nario. Recurrences are associated with prolonged initial admission, ventricular arrhythmias, younger age, inflammatory bowel disease and chronic pulmonary disease. 22 Up to 30% of biopsy- proven myo- carditis cases progress to chronic dilated cardiomyopathy. 3 Diagnostic approach AS the clinical manifestation of myocarditis lacks specific char- acteristics, an accurate diagnosis should use an integrated assess- ment that incorporates a thorough clinical assessment, ECG, serum biomarkers, non-invasive imaging and EMB data. 0.001 0.01 ECG The ECG is usually abnormal and neither specific nor sensitive for these patients. It can range from non-specific ST- and T-wave abnormalities to ST changes mim- icking ischaemia. A normal ECG does not exclude myocarditis. The presence of diffuse concave ST elevation without reciprocal changes and non-specific T-wave inversion is suggestive of myo- carditis. 23 Findings such as AV block, bundle-branch block and supraventricular and ventricular arrhythmia may also occur. A pro- longed QRS duration is a marker of severe left ventricular dysfunc- tion and also an independent pre- dictor for cardiac death or heart transplantation in patients with suspected myocarditis. 24 Serum biomarkers Serum biomarkers of myocardial injury, such as CK-MB and tro- ponin, may be elevated but are not specific for myocarditis. Higher troponin levels are of prognos- tic value. 9 Raised serum troponin concentrations are more frequent than increased CK-MB levels in these patients. 11 Thus, troponin measurement is better for identify- ing patients with myocarditis. The serum inflammatory mark- ers (leukocytes and CRP) can be elevated in the case of acute myo- carditis, but normal values do not rule out an acute myocardial inflammatory process. 9 Viral serology Mahfoud, et al evaluated the 22 | Australian Doctor | 7 July 2017 Mild myocarditis Acute heart failure Healthy individuals Severe myocarditis Medium myocardial infarction 0.1 Troponin Level (µg/L) 1 Left ventricular hypertrophy Chronic heart failure Myocarditis Mild myocardial infarction 10 100 Large myocardial infarction Figure 3. Relationship between serum troponin levels and the severity of myocardial damage caused by myocarditis, heart failure or MI. Based on Agewall S, et al. 25 Diagnostic criteria for clinically suspected myocarditis • One or more clinical presentations and one or more diagnostic criterion, or • Two or more diagnostic criteria if the patient is asymptomatic Clinical presentation • Acute chest pain resembling acute coronary syndrome or pleuritic pain that is worse in the supine position • Unexplained syndrome of heart failure (acute or subacute), including cardiogenic shock • Symptomatic arrhythmia Diagnostic criteria • ECG changes — ST-segment and T-wave changes, supraventricular/ventricular arrhythmia — Atrioventricular block (I-III degree), bundle-branch block, prolonged QRS duration equal to or greater than 120ms, Q waves, ventricular ectopic beats and sinus arrest • Positive cardiac biomarkers — Elevated cardiac troponin T and CK-MB • Functional and structural abnormalities on cardiac imaging — Regional wall motion abnormalities, impaired left or right ventricle function with or without left or right ventricle dilatation, increased ventricle wall thickness, pericardial effusion and intracavitary thrombi • Tissue characteristics on CMR — The T2-weighted myocardial oedema and the typical late gadolinium enhancement patterns for myocarditis (patchy, subepicardial or septal layer and transmural enhancement area) Source: Caforio, et al; Kindermann I, et al. 3,9 diagnostic value of viral serol- ogy in comparison with analyses of EMB, including viral genome detection, in patients with clini- cally suspected myocarditis. 26 The results of the prospective study showed that viral serology had no relevance for the diagnosis of myocardial infection. The interpretation of serologic findings is limited by a significant delay from the onset of infection, ranging from weeks to months, when the acute phase of myocar- ditis has already resolved. It is also complicated by the high prevalence of these viruses in the population in the absence of heart disease. www.australiandoctor.com.au It was reported that there was no correlation between viral serol- ogy and EMB findings. Serological examinations should no longer be used as a standard evalua- tion in the diagnostic workup of patients with suspected myocardi- tis because they are unlikely to add value to the patient’s management and would add unnecessary cost. 26 Disease-specific serum cardiac autoantibodies for myocarditis can be used as autoimmune biomark- ers and may provide adjunct diag- nostic tools to identify patients in whom immunosuppression and/or immunomodulation are of poten- tial benefit. 3 These antibodies are associated with a worse prognosis in chronic myocarditis and a bet- ter outcome in acute cases. 27 At present, the tests are only available for research purposes. Echocardiography Echocardiography and contrast- enhanced CMR are standard imag- ing tools in patients with suspected myocarditis. They are used to rule out other diagnoses and indirectly recognise myocarditis. There are no specific echocar- diographic features of myocardial inflammation. However, echocar- diography is easily accessible and is used as an initial investigation in patients with suspected myocar- ditis. It provides structural infor- mation, such as left ventricular dysfunction with reduced ejection fraction and wall motion abnor- malities, right ventricular involve- ment, ventricular wall thickening and pericardial effusion. 12 It is also a useful tool for follow-up care to monitor the abnormal parameters. Patients with fulminant myocar- ditis have an echocardiographic presentation that differs from that of patients with acute myocarditis. There is increased left ventricular wall thickness in fulminant myo- carditis that is likely due to the greater inflammatory response seen on EMB. The left ventricu- lar dimension is near normal in patients with fulminant myo- pericarditis, whereas those with acute myocarditis have marked left ventricular dilation, normal left ventricular wall thickness and cont’d page 24

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