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Recognizing COVID-19

–related myocarditis: The

possible pathophysiology and proposed guideline for

diagnosis and management

Q17

Bhurint Siripanthong, BA(Cantab),

*

Saman Nazarian, MD, PhD,

Daniele Muser, MD,

Rajat Deo, MD, MTR,

Pasquale Santangeli, MD, PhD,

Mohammed Y. Khanji, MBChB, MRCP, PhD,

Leslie T. Cooper Jr., MD,

x

C. Anwar A. Chahal, MBChB, MRCP, PhD

†{k

Q2

From the *School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom

Q3 ,†Division of

Cardiovascular Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania,

Barts Health NHS Trust, London, United Kingdom,xMayo Clinic Florida, Jacksonville, Florida, {Mayo Clinic Rochester, Rochester, Minnesota, andkRoyal Papworth Hospital, Cambridge, United

Kingdom.

Human coronavirus-associated myocarditis is known, and a number of coronavirus disease 19 (COVID-19)–related myocarditis cases have been reported. The pathophysiology of COVID-19–related myocarditis is thought to be a combination of direct viral injury and cardiac damage due to the host’s immune response. COVID-19 myocarditis diagnosis should be guided by insights from previous coronavirus and other myocarditis experience. The clinicalfindings include changes in electrocardiogram and cardiac biomarkers, and impaired cardiac function. When cardiac magnetic resonance imag-ing is not feasible, cardiac computed tomographic angiography with delayed myocardial imaging may serve to exclude significant coro-nary artery disease and identify myocardial inflammatory patterns. Because many COVID-19 patients have cardiovascular comorbid-ities, myocardial infarction should be considered. If the diagnosis

remains uncertain, an endomyocardial biopsy may help identify active cardiac infection through viral genome amplification and possibly refine the treatment risks of systemic immunosuppression. Arrhythmias are not uncommon in COVID-19 patients, but the path-ophysiology is still speculative. Nevertheless, clinicians should be vigilant to provide prompt monitoring and treatment. The long-term impact of COVID-19 myocarditis, including the majority of mild cases, remains unknown.

KEYWORDS Arrhythmias; Coronavirus disease 2019; Endomyocar-dial biopsy; Fulminant myocarditis; Interleukin 6; SARS-CoV-2 (Heart Rhythm 2020;-:1–9) Published by Elsevier Inc. on behalf of Heart Rhythm Society.

Introduction

In December 2019, coronavirus disease 2019 (COVID-19) wasfirst described in Wuhan, China, in patients complaining offlulike symptoms.1The virus was isolated and identified as a new strain of coronavirus, now named SARS-CoV-2 (se-vere acute respiratory syndrome coronavirus 2). The mortal-ity rate of COVID-19 is estimated to be,1%,2mainly due to severe acute respiratory syndrome and multiorgan dysfunc-tion. Cardiovascular complications of COVID-19 have received less medical attention; nevertheless, the first cases

of myocarditis in COVID-19 patients have been reported,3–6 and myocarditis has been recognized as the cause of death in some COVID-19 patients.7Pathology usually is focal within the myocardium, but there is a risk of arrhythmia as well as progression to fulminant heart failure and cardiogenic shock. This article outlines the possible pathophysiology of COVID-19–related myocarditis, its clinical presentation, and the associated arrhythmias. Criteria for screening and management of myocarditis relating to COVID-19 are pro-posed.

Pathophysiology of COVID-19

–related

myocarditis

General knowledge about viral myocarditis

Myocarditis is an inflammatory disease of the heart character-ized by inflammatory infiltrates and myocardial injury without an ischemic cause.8The most commonly identifiable cause of myocarditis in the United States and other developed countries is viral.9,10 Esfandiarei and McManus8proposed

This contemporary review did not receive any specific grant from fund-ing agencies in the public, commercial, or not-for-profit sectors. Dr Nazarian has been a consultant for CardioSolv and Circle Software; and has received grants from SIEMENS, Imricor, Biosense Webster, and the

Q16 National

Insti-tutes of Health (NIH). All other authors have reported that they have no con-flicts relevant to the contents of this paper to disclose.

Q1 Address reprint

requests and correspondence: Dr Anwar Chahal, University of Pennsylva-nia, Hospital of the University of PennsylvaPennsylva-nia, 3400 Spruce St, Philadel-phia, PA 19104. E-mail address:[email protected].

1547-5271/$-see front matter Published by Elsevier Inc. on behalf of Heart Rhythm Society. https://doi.org/10.1016/j.hrthm.2020.05.001 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136

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that the pathophysiology of viral myocarditis is a combina-tion of direct cell injury and T-lymphocyte–mediated cyto-toxicity, which can be augmented by the cytokine storm syndrome. Interleukin 6 (IL-6) seems to be the central medi-ator of cytokine storm, in which it orchestrates the proin flam-matory responses from immune cells, including the T lymphocytes.11This process causes T-lymphocyte activation and a further release of inflammatory cytokines, which stim-ulate more T lymphocytes, leading to a positive feedback loop of immune activation and myocardial damage. Cardio-tropism of the T lymphocytes is thought to arise from inter-action between heart-produced hepatocyte growth factor (HGF) and c-Met, an HGF receptor on naïve T lympho-cytes.12

Known human coronaviruses as the etiologic

agents of myocarditis

Despite being a minor cause of all viral myocarditis cases, human coronaviruses have been linked to myocarditis in pa-tients of all age groups.13–15The viral RNAs of Middle East respiratory syndrome coronavirus (MERS-CoV) and SARS-CoV, which are close relatives of SARS-CoV-2, were found in the heart tissues of infected animals, suggesting that these coronaviruses possess cardiotropism.16,17Furthermore, some coronavirus proteins were shown to render them highly infec-tious to the human cells. Nakagawa et al18demonstrated that MERS-CoV-D4a, a mutant MERS-CoV strain that lacks the 4a accessory protein, had less efficient replication in HeLa/ CD26 cells compared to the wild-type MERS-CoV. The 4a accessory protein is thought to inhibit protein kinase R– mediated phosphorylation of eukaryotic initiation factor 2.18Failure to phosphorylate the eukaryotic initiation factor 2 impairs stress granule formation. The stress granules help sequester the host proteins important for translation and attenuate viral protein syntheses; therefore, its suppression promotes viral replication. Similarly, SARS-CoV enhances its RNA translation via the Nsp1 protein.19

Possible pathophysiology of SARS-CoV-2

–related

myocarditis

SARS-CoV-2 gains entry into human cells by binding its spike protein to the membrane protein angiotensin-converting enzyme 2 (ACE2).20However, the spike protein must first be cleaved at the S1/S2 and subsequently at the S2ʹ sites to enable binding to ACE2. Cleavage at the S1/S2 site seems to be mediated by TMPRSS2, a serine protein.20 ACE2 can be found on the ciliated columnar epithelial cells of the respiratory tract, type II pneumocytes, and cardiomyo-cytes.21,22Therefore, it is plausible that SARS-CoV-2 infects the human heart, especially in case of heart failure as ACE2 is upregulated,23although the presence of viral receptors does not always predict tropism.24

At least 6 known accessory proteins can be transcribed by the SARS-CoV-2 genome.25Whether any of the accessory proteins provide an infectivity advantage, as in MERS-CoV and SARS-CoV, remains to be determined.Figure 1

summa-rizes the possible mechanism of SARS-CoV-2 myocardial infection. The speculated risk factors for developing COVID-19–related myocarditis are shown in Online Figure 1.

Incidence of myocarditis in COVID-19 patients

The prevalence of myocarditis among COVID-19 patients is unclear, partly because the early reports often lacked the specific diagnostic modalities to assess myocarditis. Some argued that up to 7% of COVID-19–related deaths were attributable to myocarditis.26 However, this was assumed and not based on confirmatory diagnoses of myocarditis and thus may be an overestimate. In contrast, many labora-tories are rationing tests and are first screening for known pathogens resulting influlike symptoms. If a positive path-ogen is identified, then testing for SARS-CoV-2 is not per-formed. This is erroneous and likely to miss the true frequency of SARS-CoV-2 infection because it assumes mutual exclusivity of SARS-CoV-2. One report identified 24.5% of COVID-19 patients as having coinfection with other viruses.27 Hence, it is possible that many cases of COVID-19–related myocarditis were missed due to a lack of SARS-CoV-2 diagnosis.

Certain ethnic groups may be disproportionately affected by SARS-CoV-2. COVID-19 death rates were shown to be higher among the African American population than other ethnicities in many American states.28 Although this may partially be explained by the greater number of cardiovascu-lar risk factors or the genetic predisposition to poorer cardiac outcomes,29health care disparities cannot be dismissed. Bias in the health and care provisions may be the driving force behind disproportionate suffering in minorities.

Incidence and possible mechanism of arrhythmias in COVID-19–related myocarditis

Arrhythmia is recognized as one of the possible clinical manifestations of COVID-19 patients. One observational study of the clinical characteristics of COVID-19 patients in Hubei, China, reported a 7.3% incidence of heart palpita-tions among its 137 patients.30Moreover, Wang et al31 re-ported that arrhythmia was a cause of intensive care unit transfer in 44.4% of COVID-19 patients. Caution is encour-aged when interpreting these data, as the sample size tends to be small and hence prone to overestimation. The exact nature of the arrhythmias was not usually reported, so assessing whether the arrhythmias are secondary to other conditions such as electrolyte imbalance or pre-existing arrhythmias is difficult. Therefore, the actual prevalence of arrhythmias in COVID-19 patients remains unknown. Nevertheless, ar-rhythmias could occur in the context of myocarditis. Peretto et al32reported in a recent study that 78.7% of myocarditis patients exhibited some form of ventricular arrhythmia. The characteristics of arrhythmias differ between active and healed myocarditis, suggesting that the pathophysiology is dependent on the stage of myocardial injury.32

Concerning SARS-CoV-2, the possible pathophysiology of arrhythmias includes (1) direct injury to cardiomyocytes disrupting the plasma membrane and electrical conduction; (2) infection of the pericardium causing massive edema; (3)

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ischemia from microvascular disease due to possible infec-tion of the pericytes33,34; (4) re-entrant arrhythmias due to myocardial fibrosis or scars; and (5) proinflammatory cyto-kines predisposing to arrhythmogenicity (Figure 2). Sce-narios 1, 2, and 3 could occur in the acute setting, whereas scenarios 4 and 5 occur in chronic or healed myocarditis. In scenario 5, proinflammatory cytokines (eg, IL-6) might cause displacement of plakoglobin, a desmosomal protein, from the cardiomyocyte membrane.35This could be arrhyth-mogenic, as inadequate cell-to-cell adherence is postulated to damage the cell membrane, leading to cardiac cell death and fibrofatty replacement.36Moreover, reduced surface expres-sion of desmosomal proteins is a known etiology of arrhyth-mogenic cardiomyopathies.36 Substantial evidence now suggests an increase in serum IL-6 in COVID-19 patients, especially in those with severe presentations.37Therefore, it is plausible that SARS-CoV-2 infection precipitates arrhyth-mias in patients with a genetic predisposition. Clinicians should be vigilant for arrhythmias, especially in areas where both the COVID-19 burden and the arrhythmogenic cardio-myopathy prevalence are high, such as the North-Eastern (Veneto) region of Italy.36

Diagnosing COVID-19–related myocarditis

Clinical presentation

Clinical presentation of SARS-CoV-2 myocarditis varies among cases. Some patients may present with relatively mild symptoms, such as fatigue and dyspnea,4,5 whereas others report chest pain or chest tightness on exertion.3,6 Many patients do deteriorate, showing symptoms of tachy-cardia and acute-onset heart failure with cardiogenic shock.3–5 In these severe cases, patients may also present with signs of right-sided heart failure, including raised jugu-lar venous pressure, peripheral edema, and right upper quad-rant pain.10 The most emergent presentation is fulminant myocarditis, defined as ventricular dysfunction and heart fail-ure within 2–3 weeks of contracting the virus.8 The early signs of fulminant myocarditis usually resemble those of sepsis: the patient often presents febrile with low pulse pres-sure, cold or mottled extremities

Q4 , and sinus tachycardia.10

Investigations

Results of blood tests from myocarditis patients often show elevated levels of lactate and other inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate, and procalcitonin, which usually are raised in keeping with the clinical presentation of infection. It is critical to distinguish fulminant myocarditis from sepsis becausefluid resuscitation, a common sepsis protocol, exacerbates fulmi-nant myocarditis withfluid overload. We encourage testing patients for baseline cardiac enzymes (eg, troponin and N-ter-minal pro–B-type natriuretic peptide [NT-proBNP]) on hos-pital admission, as cardiac troponin I (cTnI), cardiac troponin T (cTnT), NT-proBNP, and BNP levels usually are elevated in myocarditis due to acute myocardial injury and possible ventricular dilation. Elevations of both troponin and

NT-proBNP levels were observed in the COVID-19–related myocarditis cases.3–6 Although a negative troponin result cannot exclude myocarditis, particularly for atypical forms such as giant cell myocarditis or for those patients in the chronic phase, negative serial high-sensitivity cardiac troponin still is helpful in the acute phase and makes diag-nosis of acute myocarditis significantly less likely. InQ5 COVID-19 patients, the (NT-pro)BNP level also could in-crease secondary to myocardial stress, a possible knock-on effect from severe respiratory illness.38

Electrocardiogram (ECG) abnormalities commonly seen with pericarditis, such as ST elevation and PR depression, may be observed in myocarditis9; however, thesefindings are not sensitive in detecting the disease and their absence is not exclusionary. For example, one COVID-19–related myocar-ditis case showed neither ST elevation nor PR depression.3 Other ECG abnormalities, including new-onset bundle branch block, QT prolongation, pseudoinfarct pattern, premature ven-tricular complexes, and bradyarrhythmia with advanced atrio-ventricular nodal block, can be observed in myocarditis.

Differential diagnoses

Acute coronary syndrome

In the context of raised cardiac troponin levels, the acute cor-onary syndrome is highly suspicious, but epicardial disease can be ruled out by coronary angiography. However, many COVID-19 patients were reported to have a detectable level of cTnI, even when they had no overt cardiac symptoms38 and thefinding does not generally represent type 1 myocar-dial infarction.39It is possible that the raised troponin levelQ6

is a result of an exacerbation of the patient’s subclinical cor-onary artery disease by sepsis, which increases cardiac oxy-gen demand. This worsens oxygen supply–demand mismatch, which could precipitate ischemia that results in type 2 myocardial infarction. Serial cardiac biomarkers can help detect myocardial injury, especially in the event of rising biomarker trend.

Sepsis-related cardiomyopathy

A case series study showed that 67% of critically ill COVID-19 patients required vasopressor and that 33% developed car-diomyopathy.40 This raises suspicion of sepsis-related car-diomyopathy, a disease characterized by reversible myocardial dysfunction. The myocardial injury is thought to arise from increased nitric oxide production, which sup-presses the cardiomyocyte’s response to calcium and down-regulates the heart’s b1-adrenergic receptors.41 The 3 cardinal signs of sepsis-related cardiomyopathy are (1) left ventricular dilation; (2) impaired ejection fraction; and (3) re-covery in 7–10 days.41

Stress-induced cardiomyopathy (Takotsubo cardiomyopathy) Takotsubo cardiomyopathy is a nonischemic cardiomyopa-thy characterized by transient weakening of the cardiomyo-cytes and subsequent ballooning of the apex. Its clinicalQ7

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manifestations mimic those of acute coronary syndrome (eg, chest pain, ECG abnormalities, and elevations of cardiac bio-markers); however, Takotsubo cardiomyopathy usually is preceded by an emotional or physical stressor.42Of note, a case report described a COVID-19 patient who initially pre-sented as having reverse Takotsubo cardiomyopathy, a variant form of Takotsubo cardiomyopathy.6

Diagnostic evaluation for COVID-19

–related

myocarditis

The American Heart Association (AHA) recommends further testing for patients having signs consistent with myocarditis with 1 or more cardiac imaging methods such as echocardio-gram or cardiovascular magnetic resonance (CMR).10 The echocardiogram usually is more readily deployed because it is portable. Especially under time and resource constraints, devices such as the hand-held, point-of-care ultrasound ma-chine can be advantageous in terms of accessibility and the relative ease of disinfecting the device for infection control. The cardinal signs of myocarditis on echocardiogram are increased wall thickness, chamber dilation, and pericardial effusion in the background of ventricular systolic dysfunc-tion. Although CMR offers major imaging advantages over echocardiography, it is limited by out-of-hours availability, the requirement for some breathholding, slower throughput,

and, given the high contagiousness of COVID-19, the requirement for deep cleaning after use. If CMR is per-formed, the results should be interpreted according to the revised Lake Louise consensus criteria43: (1) edema; (2) irre-versible cell injury; and (3) hyperemia or capillary leak.

Figures 3A through 3F show the typical CMR findings of myocarditis. CMR myocardial edema and/or scarring were observed in all of the SARS-CoV-2–related myocarditis cases for which CMR results were reported.4–6 If CMR proves prohibitive, cardiac computed tomography (CT) scan with contrast enhancement and ECG gating is an effective alternative, especially when the patient is to undergo high-resolution CT scan of the chest for assessment of acute respiratory distress syndrome (Figure 3J). Contrast-enhanced cardiac CT will add very little scanning time and in this situation is particularly useful to perform a test rapidly with minimal requirement for breathholding.44 Without CMR or contrast-enhanced CT results, distinguishing myocarditis from other differential diagnoses is difficult.

Both the AHA and European Society of Cardiology (ESC) recommend endomyocardial biopsy (EMB) as the definitive diagnostic tool for myocarditis, but both societies recognize the limitations of EMB in terms of expertise required, conta-gious spread risk, and false-negative rate.9,10 If obtained, EMB samples should be immunohistochemically tested for in-flammatory infiltrates and RNA/DNA extraction performed to

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Figure 1 Proposed pathophysiology of SARS-CoV-2 myocarditis. SARS-CoV-2 utilizes the spike protein (primed by TMPRSS2) to bind ACE2 to allow cell entry. Intracellular SARS-CoV-2 might impair stress granule formation via its accessory protein. Without the stress granules, the virus is allowed to replicate and damage the cell. Naïve T lymphocytes can be primed for viral antigens via antigen-presenting cells and cardiotropism by the heart-produced HGF. The HGF binds c-Met, an HGF receptor on T lymphocytes. The primed CD81 T lymphocytes migrate to the cardiomyocytes and cause myocardial inflammation through cell-mediated cytotoxicity. In the cytokine storm syndrome, in which proinflammatory cytokines are released into the circulation, T-lymphocyte activation is augmented and releases more cytokines. This results in a positive feedback loop of immune activation and myocardial damage. ACE2 5 angiotensin-converting enzyme 2; APC5 antigen-presenting cell; HGF 5 hepatocyte growth factor; IL-6 5 interleukin 6; MHC 5 major histocompatibility complex; SARS-CoV-25 severe acute respiratory syndrome coronavirus 2; TCR 5 T-cell receptor.

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test for the presence of viral genomes.45Regarding the conta-gious spread risk, should coronary angiography be deemed necessary, it is reasonable to perform the right heart procedures and/or EMB concomitantly as these will add minimal risk while adding 15 minutes to the procedure time. EMB also serves as an opportunity for accurate diagnosis and provides tissues for the development of specific biomarkers, which could be useful for developing a diagnostic test for SARS-CoV-2 myocarditis. In the event of patient death, we suggest that an autopsy, including the heart, be performed because it will allow observa-tion of the gross and microscopic pathology of the heart, including multiple left and right ventricular segments. This may illuminate the new biological pathways for COVID-19 treatments—knowledge that is critically needed and will bring immense societal benefit in this trying time.

Chronic complications of COVID-19–related myocarditis While the acute inflammation and injury to the heart are the current focus receiving attention, the long-term effects of healed myocarditis are completely unknown. Most in-fected patients experience mild, self-limiting symptoms; are managed in the community; and are not undergoing clinical testing such as ECG or cardiac imaging. Because the emphasis is evaluating and admitting patients with severe lower respiratory tract symptoms, many patients with possible myocarditis will never be evaluated. Some of these patients may survive the acute event but may be at risk for

subsequent arrhythmias. In a study of patients with active and healed myocarditis, monomorphic ventricular tachy-cardia and regular ventricular arrhythmias were more frequent in those with healed than acute myocarditis.32 How-ever, the presence of viral genomes on EMB was not associ-ated with the occurrence of malignant arrhythmias.32

Management of COVID-19–related myocarditis and ar-rhythmias

Managing myocarditis

The AHA recently published a scientific statement on the recognition and initial management of fulminant myocar-ditis.10It recommends implementing the initial management protocol for cardiogenic shock in patients with fulminant myocarditis. This includes administration of inotropes and/or vasopressors and mechanical ventilation. Longer-term man-agement involves mechanical circulatory support such as extracorporeal membrane oxygenation, ventricular assist de-vice, or intra-aortic balloon pump. The ESC did not endorse the use of intravenous immunoglobulin due to a lack of sup-porting evidence,9and it discouraged the use of corticosteroids in active-infection myocarditis, citing the ineffectiveness of corticosteroids in a randomized controlled trial.46

Case reports of coronavirus-related myocarditis provide a glimpse into the efficacy of some of the aforementioned

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Figure 2 Arrhythmogenesis in SARS-CoV-2–related myocarditis. Possible mechanisms responsible for arrhythmias in SARS-CoV-2–related myocarditis are shown. Mechanisms 1, 2, and 3 could occur in the acute setting, whereas mechanisms 4 and 5 occur in chronic/healed myocarditis. Abbreviations as inFigure 1. (Modified with permission from Peretto et al.33)

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treatments.Online Table 1summarizes 9 case reports of pa-tients with coronavirus-related myocarditis. Mechanical cir-culatory support was deployed in 2 of 7 cases (for which treatment modalities were reported).3,47 Presumably, in a more hemodynamically stable case, medical treatment con-sisting of inotropes or vasopressors was sufficient to mitigate the ventricular systolic dysfunction.4,13,48 In some cases, immunomodulatory treatments were given. Zeng et al3and Hu et al48reported the use of corticosteroid and intravenous immunoglobulin. A recent meta-analysis on corticosteroid and intravenous immunoglobulin use in pediatric myocar-ditis concluded that intravenous immunoglobulin may improve ventricular systolic function but failed tofind sup-port for corticosteroid use.49However, immunosuppression might pose a risk for more severe clinical disease, especially in the presence of active viral replication. Therefore, it is reasonable to withhold or minimize the use of immunosup-pression in SARS-CoV-2 patients, especially in the setting of a positive viral genome on EMB. Tocilizumab, an anti– IL-6 receptor monoclonal antibody, is now being tested in a multicenter randomized controlled trial that recruits COVID-19 patients with raised IL-6 levels.50This antibody might be beneficial in the setting of cytokine storm syndrome and help reduce myocardial inflammation.

Managing arrhythmias

Managing arrhythmias is crucial in mitigating a patient’s adverse health outcomes. Cardiac monitoring is advised to enable appropriate therapy for brady- and tachyarrhythmias, including atrioventricular block, and ventricular tachycardia orfibrillation. Bradyarrhythmias may require temporary car-diac pacing, and tachyarrhythmias may respond to antiar-rhythmic drugs (eg, lidocaine and mexiletine) and overdrive pacing. Some centers have commenced prescrip-tion of antimalarials and macrolides, which are known to pro-long the QTc interval. Caution must be taken with concomitant use of antiarrhythmic drugs.51

Cardiovascular considerations regarding COVID-19

therapeutics

Several potential pharmacologic candidates being repur-posed for use in COVID-19 patients are under investigation. Currently, chloroquine is under a phase IIb clinical trial to assess its efficacy in treating COVID-19 patients with severe respiratory syndrome.52Both chloroquine and its derivative, hydroxychloroquine, may cause QTc interval prolongation; however, their effects seem to be modest.51 Nevertheless, (hydroxy)chloroquine requires metabolism by the CYP3A4 enzyme,53 whose inhibition might raise the drug’s plasma concentration, accentuating the long QT risk. Many

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Figure 3 Typical cardiovascular magnetic resonance (CMR) and computed tomography (CT)findings of myocarditis. A, D: Cardiac edema (yellow arrows) in T2-weighted mode. B, C: LGE of the subepicardial region (yellow arrows) of the ventricles, a sign of myocardialfibrosis or scarring. E: Midmyocardial LGE (yellow arrows) is often present in the acute setting and resolved at follow-up. F: LGE resolved in the chronic case. These areas may initially represent acute myocardial edema (yellow arrows) and resolve over time. G, H: CMR imaging of region-of-interest measurements obtained before (G) and after (H) gadolinium chelate administration. I, J: Reformatted cardiac CT of region-of-interest measurements obtained before (I) and after (J) administration of an iodinated contrast agent. For cardiac CT, the antero-lateral myocardium was most reliably identified before administration of an iodinated contrast agent. In that area, a region of interest from the anterolateral

myocardium was used for attenuation measurements. A focal myocardial scar was identified on delayed CMR images and was not included in the region of interest. Orange outline indicates myocardium; white circle indicates blood pool. LGE5 late gadolinium enhancement. (A–F modified from Kociol et al10and G–J from Nacif et al44with permission.)

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pharmacologic agents used empirically to treat COVID-19, including ritonavir/lopinavir and azithromycin, are known CYP3A4 inhibitors; hence, their combination therapy with (hydroxy)chloroquine should be accompanied by QTc inter-val monitoring.51

Given that SARS-CoV-2 binds to ACE2 to gain host cell entry, there is ongoing debate on whether renin-angiotensin-aldosterone system (RAAS) antagonists should be used in COVID-19 patients. Some argued that the blockade might offer clinical benefit,54whereas others queried the possible upregulation of ACE2 as a consequence of such blockades. However, according to the current clinical evidence, the Heart Failure Society of America, the American College of Cardiology, and AHA advise continuing the RAAS antago-nist regimen if prescribed for their approved indications, even when the patient contracts COVID-19 later.

Q8 55 Both

the AHA10and ESC9advised against the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in myocarditis patients because they are the known cause of renal impairment and sodium retention, which could exacerbate acute ventricular dysfunction. Our recommendation for the diagnosis and management of SARS-CoV-2–related myocarditis is sum-marized inFigure 4.

Conclusion

Several cases of coronavirus-related myocarditis have been reported. Its pathophysiology likely is a combination of the direct viral insult to cardiomyocytes and the human’s immune response to virally infected myocardium. Simple bedside tests such as serial ECG and cardiac biomarkers can raise suspicion of acute-onset cardiac symptoms. Particular attention should be given to biomarkers changes or trends and not just readings obtained in isolation. Cardiac imaging techniques such as echocardiography and CMR can be used to aid diagnosis; however, distinguishing between differential diagnoses of stress-induced cardiomyopathy, sepsis-related cardiomyopa-thy, and acute coronary syndrome can be difficult. An inva-sive coronary angiogram will often be warranted, especially in older patients. The definitive diagnosis of myocarditis is obtained via EMB, and if an invasive catheterization is to be performed, concomitant EMB would add little time and no further risk of infection spread vs catheterization alone.Q9 For patients who cannot undergo CMR, contrast-enhanced cardiac CT is a swift, reproducible, precise, and reliable alter-native that can be added to the sequences for high-resolution CT of the lungs to evaluate the acute respiratory distress syn-drome. Initial treatment of fulminant myocarditis should

print & web 4C =FP O

Figure 4 Suggested diagnostic and management protocol for SARS-CoV-2–related myocarditis. DD 5 differential diagnoses; ACS 5 acute coronary syn-drome; CAR5 chimeric antigen receptor;CMR5 cardiovascular magnetic resonance; CO 5 cardiac output; COVID-19 5 coronavirus 19; CRP 5 C-reactiveQ15

protein; CT5 computed tomography; CT-CA 5 computed tomography–coronary angiogram; cTnI 5 cardiac troponin I; cTnT 5 cardiac troponin T; DCCV 5 direct current cardioversion; ECG5 electrocardiogram; ECMO 5 extracorporeal membrane oxygenation; EMB 5 endomyocardial biopsy; ESR 5 erythrocyte sedimentation rate; IABP5 intra-aortic balloon pump; IL-6 5 interleukin 6; IV 5 intravenous; IVIG 5 intravenous immunoglobulin; NSAID 5 nonsteroidal anti-inflammatory drug; NT-proBNP 5 N-terminal pro–B-type natriuretic peptide; SARS-CoV-2 5 severe acute respiratory syndrome coronavirus 2; TTE 5 transthoracic echocardiogram; US5 ultrasound; VAD 5 ventricular assist device.

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follow the cardiogenic shock protocol, which includes the use of inotropes or vasopressors and mechanical ventilation. Ar-rhythmias can be managed by temporary cardiac pacing or antiarrhythmic medications. Then, depending on severity, the patient may require mechanical circulatory support. Cau-tions must be taken for the use of the NSAIDs and QTc-prolonging drugs in COVID-19 patients because these medi-cations might exacerbate cardiac symptoms.

Appendix

Supplementary data

Supplementary data associated with this article can be found in the online version athttps://doi.org/10.1016/j.hrthm.2020. 05.001.

References

1. Zhu N, Zhang D, Wang W, et al. A novel coronavirus from patients with pneu-monia in China, 2019. N Engl J Med 2020;382:727–733.

2. Mahase E. Covid-19: death rate is 0.66% and increases with age, study estimates. BMJ 2020;369:m1327.

3. Zeng J-H, Liu Y-X, Yuan J, et al. First case of COVID-19 infection with fulmi-nant myocarditis complication: case report and insights. Published online April 10. Infection 2020;https://doi.org/10.1007/s15010-020-01424-5.

Q10

4. Inciardi RM, Lupi L, Zaccone G, et al. Cardiac involvement in a patient with co-ronavirus disease 2019 (COVID-19). Published online March 27, 2020. JAMA Cardiol doi:10.1001/jamacardio.2020.1096

5. Kim I-C, Kim JY, Kim HA, Han S. COVID-19-related myocarditis in a 21-year-old female patient. Eur Heart J 2020;41:1859.

6. Sala S, Peretto G, Gramegna M, et al. Acute myocarditis presenting as a reverse Tako-Tsubo syndrome in a patient with SARS-CoV-2 respiratory infection. Eur Heart J 2020;41:1861–1862.

7. Ruan Q, Yang K, Wang W, Jiang L, Song J. Clinical predictors of mortality due to COVID-19 based on an analysis of data of 150 patients from Wuhan, China. Intensive Care Med. Intensive Care Med 2020;46:846–848.

https://doi.org/10.1007/s00134-020-06028-z. Published correction appears on-line April 6, 2020.

Q11

8. Esfandiarei M, McManus BM. Molecular biology and pathogenesis of viral myocarditis. Annu Rev Pathol 2008;3:127–155.

9. Caforio AL, Pankuweit S, Arbustini E, et al. Current state of knowledge on aeti-ology, diagnosis, management, and therapy of myocarditis: a position statement of the European Society of Cardiology Working Group on Myocardial and Peri-cardial Diseases. Eur Heart J 2013;34:2636–2648.

Q12

10. Kociol RD, Cooper LT, Fang JC, et al. Recognition and initial management of fulminant myocarditis: a scientific statement from the American Heart Associa-tion. Circulation 2020;141:e69–e92.

11. Lee DW, Gardner R, Porter DL, et al. Current concepts in the diagnosis and man-agement of cytokine release syndrome. Blood 2014;124:188–195.

12. Komarowska I, Coe D, Wang G, et al. Hepatocyte growth factor receptor c-Met instructs T cell cardiotropism and promotes t cell migration to the heart via auto-crine chemokine release. Immunity 2015;42:1087–1099.

13. Chantreuil J, Favrais G, Soule N, et al. Tachycardie atriale chaotique au cours d’une infection respiratoire a coronavirus NL63. Arch Pediatr 2013;20:278–281. 14. Riski H, Hovi T, Frick MH. Carditis associated with coronavirus infection. Lancet

1980;2:100–101.

15. Alhogbani T. Acute myocarditis associated with novel Middle East respiratory syndrome coronavirus. Ann Saudi Med 2016;36:78–80.

16. Agrawal AS, Garron T, Tao X, et al. Generation of a transgenic mouse model of Middle East respiratory syndrome coronavirus infection and disease. J Virol 2015;89:3659–3670.

17. Schaecher SR, Stabenow J, Oberle C, et al. An immunosuppressed Syrian golden hamster model for SARS-CoV infection. Virology 2008;380:312–321. 18. Nakagawa K, Narayanan K, Wada M, Makino S. Inhibition of stress granule

for-mation by Middle East respiratory syndrome coronavirus 4a accessory protein fa-cilitates viral translation, leading to efficient virus replication. J Virol 2018; 92:e00902–e00918.

19. Narayanan K, Huang C, Lokugamage K, et al. Severe acute respiratory syndrome coronavirus nsp1 suppresses host gene expression, including that of type I inter-feron, in infected cells. J Virol 2008;82:4471–4479.

20. Hoffmann M, Kleine-Weber H, Schroeder S, et al. SARS-CoV-2 cell entry de-pends on ACE2 and TMPRSS2 and is blocked by a clinically proven protease in-hibitor. Cell 2020;181:271–280.e8.

21. Qian Z, Travanty EA, Oko L, et al. Innate immune response of human alveolar type II cells infected with severe acute respiratory syndrome-coronavirus. Am J Respir Cell Mol Biol 2013;48:742–748.

22. Goulter AB, Goddard MJ, Allen JC, Clark KL. ACE2 gene expression is up-regulated in the human failing heart. BMC Med 2004;2:19.

23. Guo J, Wei X, Li Q, et al. Single-cell RNA analysis on ACE2 expression provides insight into SARS-CoV-2 blood entry and heart injury. Preprint. Posted online April 2020;4 https://doi.org/10.1101/2020.03.31.20047621. medRxiv 2020.03.31.20047621.

24. Weiss SR. Forty years with coronaviruses. J Exp Med 2020;217:e20200537. 25. Kim D, Lee J-Y, Yang J-S, Kim JW, Kim VN, Chang H. The architecture of

SARS-CoV-2 transcriptome. Cell 2020;181:914–921.e10.

26. Driggin E, Madhavan MV, Bikdeli B, et al. Cardiovascular considerations for pa-tients, health care workers, and health systems during the coronavirus disease 2019 (COVID-19) pandemic. J Am Coll Cardiol 2020;75:2352–2371. 27. Shah N. Higher co-infection rates in COVID19. March 18,https://medium.

com/@nigam/higher-co-infection-rates-in-covid19-b24965088333. Accessed April 22, 2020.

28. Yancy CW. COVID-19 and African Americans. JAMA 2020;323:1891–1892. 29. Myers VD, Gerhard GS, McNamara DM, et al. Association of variants in BAG3

with cardiomyopathy outcomes in African American individuals. JAMA Cardiol 2018;3:929–938.

30. Liu K, Fang YY, Deng Y, et al. Clinical characteristics of novel coronavirus cases in tertiary hospitals in Hubei Province. Chin Med J 2020;133:1025–1031. 31. Wang D, Hu B, Hu C, et al. Clinical characteristics of 138 hospitalized patients

with 2019 novel coronavirus-infected pneumonia in Wuhan, China. JAMA 2020;323:1061–1069.

32. Peretto G, Sala S, Rizzo S, et al. Ventricular arrhythmias in myocarditis: charac-terization and relationships with myocardial inflammation. J Am Coll Cardiol 2020;75:1046–1057.

33. Peretto G, Sala S, Rizzo S, et al. Arrhythmias in myocarditis: state of the art. Heart Rhythm 2019;16:793–801.

34. Chen L, Li X, Chen M, Feng Y, Xiong C. The ACE2 expression in human heart indicates new potential mechanism of heart injury among patients infected with SARS-CoV-2. Cardiovasc Res 2020;116:1097–1100.

35. Asimaki A, Tandri H, Duffy ER, et al. Altered desmosomal proteins in gran-ulomatous myocarditis and potential pathogenic links to arrhythmogenic right ventricular cardiomyopathy. Circ Arrhythm Electrophysiol 2011; 4:743–752.

36. Gemayel C, Pelliccia A, Thompson PD. Arrhythmogenic right ventricular cardio-myopathy. J Am Coll Cardiol 2001;38:1773–1781.

37. Coomes EA, Haghbayan H. Interleukin-6 in COVID-19: a systematic review and meta-analysis. Preprint. Posted online April 2020;3

https://doi.org/10.1101/2020.03.30.20048058. medRxiv 2020.03.30.20048058. 38. Januzzi JL. Troponin and BNP use in COVID-19. Cardiology Magazine. March

2020;18, https://www.acc.org/latest-in-cardiology/articles/2020/03/18/15/25/ troponin-and-bnp-use-in-covid19.

39. Clerkin KJ, Fried JA, Raikhelkar J, et al. COVID-19 and cardiovascular disease. Circulation 2020;141:1648–1655.

40. Arentz M, Yim E, Klaff L, et al. Characteristics and outcomes of 21 critically ill patients with COVID-19 in Washington State. JAMA 2020;323:1612–1614. 41. Sato R, Nasu M. A review of sepsis-induced cardiomyopathy. J Intensive Care

2015;3:48.

42. Pelliccia F, Kaski JC, Crea F, Camici PG. Pathophysiology of Takotsubo syn-drome. Circulation 2017;135:2426–2441.

43. Friedrich MG, Sechtem U, Schulz-Menger J, et al. Cardiovascular magnetic reso-nance in myocarditis: a JACC White Paper. J Am Coll Cardiol 2009; 53:1475–1487.

44. Nacif MS, Kawel N, Lee JJ, et al. Interstitial myocardialfibrosis assessed as extra-cellular volume fraction with low-radiation-dose cardiac CT. Radiology 2012; 264:876–883.

45. Leone O, Veinot JP, Angelini A, et al. 2011 Consensus statement on endomyo-cardial biopsy from the Association for European Cardiovascular Pathology and the Society for Cardiovascular Pathology. Cardiovasc Pathol 2012; 21:245–274.

46. Mason JW, O’Connell JB, Herskowitz A, et al. A clinical trial of immunosuppres-sive therapy for myocarditis. N Engl J Med 1995;333:269–275.

47. Rao S, Sasser W, Diaz F, Sharma N, Alten J. Coronavirus associated fulminant myocarditis successfully treated with intravenous immunoglobulin and extracor-poreal membrane oxygenation. Chest 2014;146:336A.

48. Hu H, Ma F, Wei X, Fang Y. Coronavirus fulminant myocarditis saved with glucocorticoid and human immunoglobulin. Eur Heart J 2020. ehaa190.

8 Heart Rhythm, Vol-, No -, - 2020

953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088

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49. Li Y, Yu Y, Chen S, Liao Y, Du J. Corticosteroids and intravenous immunoglob-ulin in pediatric myocarditis: a meta-analysis. Front Pediatr 2019;7:342. 50. Favipiravir Combined With Tocilizumab in the Treatment of Corona Virus

Disease, https://clinicaltrials.gov/ct2/show/NCT04310228. Accessed April 22, 2020.

51. Wu CI, Postema PG, Arbelo E, et al. SARS-CoV-2, COVID-19, and inherited arrhythmia syndromes. Published online March 31, 2020. Heart Rhythm doi:10.1016/j.hrthm.2020.03.024

52. Borba MGS, Val F de A, Sampaio VS, et al. Chloroquine diphosphate in two different dosages as adjunctive therapy of hospitalized patients with severe respi-ratory syndrome in the context of coronavirus (SARS-CoV-2) infection: prelim-inary safety results of a randomized, double-blinded, phase IIb clinical trial

(CloroCovid-19 Study). Preprint. Posted online April 2020;16

https://doi.org/10.1101/2020.04.07.20056424. medRxiv 2020.04.07.20056424. Q13

53. Kim KA, Park JY, Lee JS, Lim S. Cytochrome P450 2C8 and CYP3A4/5 are involved in chloroquine metabolism in human liver microsomes. Arch Pharm Res 2003;26:631–637.

54. Sun ML, Yang JM, Sun YP, Su GH. [Inhibitors of RAS might be a good choice for the therapy of COVID-19 pneumonia]. Zhonghua Jie He He Hu Xi Za Zhi

2020;43:219–222. Q14

55. HFSA/ACC/AHA Statement Addresses Concerns Re: Using RAAS Antagonists in COVID-19. ACC New Story. March 16, 2020, https://www.acc.org/latest-in- cardiology/articles/2020/03/17/08/59/hfsa-acc-aha-statement-addresses-concerns-re-using-raas-antagonists-in-covid-19. 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224

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