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Case Report ??? Acta Cardiol Sin 2010;26:44-7

Acute Viral Mimicking ST Elevation Myocardial : Manifestation on Cardiac Magnetic Resonance

Yi-Da Li,1 Fu-Tsung Hsiao,2 Cha-Po Lai1 and Chih-Wei Chen1,3

A 58-year-old man presented himself to the emergency room with chief complaints of chest and progressively exacerbated dyspnea for 4 days. showed Q wave and ST-segment elevation in inferior leads. A thallium scan showed mixed and infarction in the inferior wall of the left . However, coronary angiography showed normal coronary . Cardiac magnetic resonance showed a typical pattern of delayed enhancement in myocarditis. A viral serological study identified coxsackievirus B6 . We report a case of acute viral myocarditis mimicking ST elevation and suggest that cardiac magnetic resonance with Gadolinium enhancement might be an effective method to detect acute viral myocarditis.

Key Words: Cardiac magnetic resonance · Coxsackievirus B · Delayed enhancement · Myocardial infarction · Myocarditis

INTRODUCTION CASE REPORT

Acute myocarditis is one of the most challenging di- A 58-year-old man had symptoms of acute upper re- agnoses in . It can present with various clini- spiratory infection, including cough, poor appetite, and cal manifestations, including mimicking acute ST-eleva- watery diarrhea, that had been ongoing for 1 week be- tion myocardial infarction.1 The diagnostic gold standard fore hospitalization. He experienced one episode of se- of myocarditis is endomyocardial biopsy (EMB) with the vere about 4 days before admission. He com- histological Dallas criteria. However, EMB is limited by plained of intermittent chest pain and progressively ex- high variability and sampling error. Recently, some new acerbated dyspnea on exertion since then. An electrocar- non-invasive methods have been proposed to accurately diogram (ECG) obtained in the emergency room showed differentiate acute myocarditis from acute myocardial in- Q wave and ST-segment elevation in inferior leads (Fig- farction.2,3 We report here a case of acute viral myo- ure 1A). Chest X-ray showed and pulmo- mimicking ST elevation myocardial infarction nary congestion. Laboratory data indicated elevated car- with typical manifestations on cardiac magnetic reso- diac enzyme concentrations ( I: 6.63 ng/ml; nor- nance (CMR) with gadolinium enhancement. mal range: < 0.11 ng/ml). The patient was admitted to the cardiovascular care unit. Trans-thoracic showed diffuse Received: March 9, 2009 Accepted: May 26, 2009 hypokinesis, especially of the inferior wall, with im- 1Section of Cardiology, Department of Internal Medicine; 2Depart- ment of Radiology, Buddhist Dalin Tzu Chi General Hospital, Chia- paired left ventricular of 47%. He re- Yi, Taiwan; 3College of Medicine, Tzu Chi University, Hualien, Taiwan. ceived a thallium-201 scan, which indicated a mixed Address correspondence and reprint requests to: Dr. Chih-Wei Chen, type of perfusion defect with ischemia and infarction in Section of Cardiology, Department of Internal Medicine, Buddhist Dalin Tzu Chi General Hospital. Tel: 886-935-609962; E-mail: the inferior wall of left ventricle. Given a tentative diag- [email protected] nosis of recent ST-elevation myocardial infarction com-

Acta Cardiol Sin 2010;26:44-7 44 Viral Myocarditis and Cardiac Magnetic Resonance

A

BC

D Figure 1. (A) Twelve-lead electrocardiogram on admission shows Q wave and ST-segment elevation in inferior leads. (B) Coronary angiography. Right-anterior-oblique (RAO) cranial view of left coronary artery shows patent left anterior descending artery and left circumflex artery. (C) Left-an- terior-oblique (LAO) view of right coronary artery shows patent right coronary artery. (D) Follow-up twelve-lead electrocardiogram 2 months after discharge still shows Q wave in inferior leads.

45 Acta Cardiol Sin 2010;26:44-7 Yi-DaLietal. plicated by congestive failure, coronary angiography DISCUSSION was performed (Figures 1B, C). However, coronary an- giography showed that the were normal. Myocarditis is a with variable prognosis, Acute viral myocarditis was highly suspected. CMR ranging from spontaneous complete recovery to dilated with intravenous injection of gadolinium was performed and even sudden .4 The patho- on the second day after he undergoing coronary angio- genesis of viral myocarditis follows a chronological se- graphy and showed subepicardial and centromyocardial quence of three pathologically distinct phases: direct vi- delayed enhancement in the inferior and posteroseptal ral invasion, immune dysregulation, and extensive myo- wall of the left ventricle (Figure 2). Viral serological cardial .4 The direct viral-mediated destruction that analysis detected a coxsackievirus B6 infection. The pa- occurs in the first phase results in focal myocardial inju- tient’s symptoms were relieved soon after treatment for ries,5 that can mimic symptoms of acute myocardial in- , and he was discharged in stable condition 6 farction, such as focal ST-segment elevation on ECG days later. and elevated cardiac enzyme concentrations. Viral infec- Follow-up echocardiography at 2 weeks and 2 months tions trigger cellular and humoral immune responses. showed normal global left ventricular function with ejec- Some mimicked epitopes are shared between the viral tion fractions of 61% and 67%, respectively. However, and cardiac antigens.6 During the second phase, auto-an- the twelve-lead ECG (Figure 1D) followed-up at 2 tibodies against cardiomyocytes are induced by molecu- months still showed Q wave in inferior leads which lar mimicry between the viral and cardiac antigens, could not be used to differentiate myocarditis from myo- which is followed by autoimmune responses.7 Finally, cardial infarction. extensive myocardial injury and even dilated cardio-

A B

Figure 2. (A) Short-axis FIESTA MR image shows focal hyperintense signals indicating edematous changes within the myocardium and subepicardium of inferior and postero- septal wall of the mid level of the left ventricle (arrow). (B) Short-axis first-pass perfusion MR image shows focal perfusion defect in the area (arrow) mentioned in Figure (A); this defect corresponds to the delayed en- hancement seen in the delayed enhancement C image (C) (arrow).

Acta Cardiol Sin 2010;26:44-7 46 Viral Myocarditis and Cardiac Magnetic Resonance myopathy can develop in the third phase.4 These patho- ECG changes and thallium-201 scan findings. genic processes might explain the clinical manifestations The clinical symptoms experienced by our patient of this patient. All of the ECG and imaging studies, in- (e.g., acute chest pain and elevated ST-segment changes) cluding the thallium-201 scan and the echocardiography, can indicate of several different types of cardiac disease, showed focal regional wall damage that might have re- including coronary artery , acute myocarditis, sulted from direct viral invasion during the first phase of and . The present findings indicate that CMR pathogenesis. The diffuse hypokinesis of the left ventri- with contrast enhancement might be an effective method cle, which was evident on echocardiography, might have for diagnosing acute myocarditis. resulted from autoimmune responses during the second phase of pathogenesis. CMR has proven helpful in not only diagnosing REFERENCES myocarditis but also in showing the extent of myocardial with delayed contrast enhancement.8 In addition, 1. Moitard N, Mewion N, Bonnefoy E, et al. Acute myocarditis EMB from a location determined by CMR can increase the mimicking lateral myocardial infarction. Anaesth Intensive Care chances of detecting acute myocarditis pathologically.9 2008;36:739-42. 2. Laissy JP, Hyafil F, Feldman LJ, et al. Differentiating acute myo- The mechanism of delayed enhancement of CMR in cardial infarction from myocarditis: diagnostic value of early- and acute myocarditis has not been fully elucidated. CMR delayed-perfusion cardiac MR imaging. Radiology 2005;237: contrast agents, such as gadolinium, cannot enter cardio- 75-82. myocytes because of their intact cell membranes.8 In the 3. Boussel L,Gamondes D,Staat P, et al. Acute chest pain with nor- setting of acute myocarditis, the ruptured sarcolemmal mal coronary angiogram: role of contrast-enhanced multidetector membranes of damaged cardiomyocytes allow the extra- computed tomography in the differential diagnosis between myo- cellular contrast to diffuse into the cells. During healing, carditis and myocardial infarction. J Comput Assist Tomogr 2008; 32:228-32. the intercellular spaces increase because necrotic cardio- 4. Mason JW. Myocarditis and : an inflam- myocytes are replaced by fibrous tissue, which increases matory link. Cardiovasc Res 2003;60:5-10. the distribution space for extracellular contrast agents. 5. McManus BM, Chow LH, Wilson JE, et al. Direct myocardial in- Both enlarged intracellular and intercellular contrast dis- jury by enterovirus: a central role in the evolution of murine myo- tribution volume are possibly responsible for the delayed carditis. Clin Immunol Immunopathol 1993;68:159-69. enhancement during CMR.9 6. Badorff C, Knowlton KU. Dystrophin disruption in enterovirus- The typical pattern of delayed enhancement during induced myocarditis and dilated cardiomyopathy: from bench to bedside. Med Microbiol Immunol 2004;193:121-6. CMR for acute myocarditis is a patchy distribution origi- 7. Caforio AL, Mahon NJ, Tona F, McKenna WJ. Circulating car- nating from the epicardial quartile of the wall with one diac autoantibodies in dilated cardiomyopathy and myocarditis: 10 or several foci. The of delayed enhance- pathogenetic and clinical significance. Eur J Heart Fail 2002; ment, by location, is as follows: lateral free wall (85%), 4:411-7. posterior and inferior walls (46%), septum (31%), and 8. Fridrich MG, Strohm O, Schulz-Menger J, et al. Contrast media- anterior wall (23%).10 Another distinct pattern of de- enhanced magnetic resonance imaging visualizes myocardial layed enhancement originates from the subendocardium changes in the course of viral myocarditis. Circulation 1998; 97:1802-9. corresponding to a coronary artery distribution is typical 9. Mahrholdt H, Goedecke C, Wagner A, et al. Cardiovascular mag- in myocardial infarction, but has never been seen in netic resonance assessment of human myocarditis: a comparison 3 myocarditis. In the present case, we could not distin- to history and molecular pathology. Circulation 2004;109:1250- guish myocardial infarction from myocarditis by ECG or 8. with a thallium-201 scan, which showed only inferior 10. Camastra GS, Cacciotti L, Marconi F, et al. Late enhancement wall damage. However, a typical pattern of subepicardial detected by cardiac magnetic resonance imaging in acute myo- and centromyocardial delayed enhancement in the infe- carditis mimicking acute myocardial infarction: location patterns and lack of correlation with systolic function. J Cardiovasc Med rior and posteroseptal wall was evident by CMR, which 2007;8:1029-33. indicated acute myocarditis and was compatible with the

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