PDF
Citation
Print
Differential diagnosis of chest pain in the pediatric population is important but can be challenging, especially in patients at risk for cardiomyopathy. We present a case of acute pericarditis in a 12-year-old boy with Duchenne muscular dystrophy (DMD) whose initial electrocardiogram (ECG) and cardiac enzyme levels were suggestive of ST-elevation myocardial infarction.
CASE REPORT
This work complies with the ethical standards of the relevant national guidelines on human medical regulations and with the Helsinki Declaration of 1975, as revised in 2008, and has been approved by the Institutional Review Board of Seoul National University Hospital (July 20th, 2020; IRB No. H-2007-099-1141). Because there is less than minimal risk to the patient, we submitted the waiver of informed consent to the IRB and obtained permission for waiver of consent.
A 12-year-old boy with DMD who is a wheelchair user presented to the emergency department with anterior chest pain in the sitting position that began 7 hours prior and radiated to the left back. The pain increased with inspiration. Four days previously, he had developed mild rhinorrhea and diarrhea without fever. Initial vital signs on arrival were as follows: blood pressure, 118/77 mm Hg; pulse rate, 79 beats per minute; respiratory rate, 18 breaths per minute; and body temperature, 36°C. The last echocardiography performed 2 years prior showed normal cardiac function, and there was no abnormality in the last ECG.
A chest radiograph on arrival revealed the absence of cardiomegaly (Figure 1A). The initial ECG revealed convex ST elevation in leads II, III, aVF, and V6, with reciprocal ST depression in V1-3 (Figure 2A). Laboratory results revealed elevated troponin-I (20.97 ng/ml) and creatine kinase MB isoenzyme (147.9 ng/ml) and normal brain natriuretic peptide (BNP; 30 pg/ml) levels. Suspecting acute myocardial infarction, we performed invasive coronary angiography, which revealed normal coronary arteries (Supplementary Video 1). After angiography, he was admitted to the pediatric intensive care unit for close monitoring of ECG changes. The echocardiograph on admission revealed normal left ventricular function (ejection fraction [EF], 66.2%) without regional wall motion abnormalities.
Although the convex ST elevations and reciprocal changes on ECG remained aggravated at 3 hours post-admission (Figure 2B), an acute pericarditis pattern with concave ST elevations in most leads including V2-3 and PR depression developed 12 hours post-admission (Figure 2C). The next day, troponin-I level increased to 107.96 ng/ml, and follow-up echocardiography revealed mild global left ventricular dysfunction (EF, 41%) without visible pericardial thickening or effusion (Figure 1B, Supplementary Video 2). On the fifth day, the BNP level increased to 122 pg/ml. Cardiac magnetic resonance imaging (MRI) showed mild global left ventricular dysfunction (EF, 48.1%) with late gadolinium enhancement in the subepicardium of the left ventricular inferolateral and mid-septal walls (Figure 1C and D). Respiratory viral polymerase chain reaction assay from a nasopharyngeal swab revealed a positive result for human coronavirus OC43. Tests for all other cardiotropic viruses including enterovirus, parvovirus B19, human herpes virus, influenza virus, coxsackievirus, respiratory syncytial virus, adenovirus, and Epstein–Barr virus were negative.
Suspecting acute viral pericarditis, we administered ibuprofen. Furthermore, a continuous milrinone infusion was commenced as the left ventricular function deteriorated rapidly within one day and cardiac MRI findings were suggestive of acute myocarditis. The chest pain improved by the next day, and the ST segment elevation normalized on the fourth day (Figure 2D). Echocardiography on the ninth day revealed improved left ventricular function (EF, 54%), and intravenous milrinone was replaced with enalapril and carvedilol. The patient was discharged on the 11th day.
After 12 months of follow-up, he is doing well without chest pain. The last ECG showed normal sinus rhythm without pathologic ST-T changes, and a follow-up cardiac MRI performed at 4-month post-disease onset showed preserved left ventricular systolic function (EF, 54%) without change of late gadolinium enhancement in the left ventricular inferolateral wall, which was regarded as a sequela of previous myocarditis. The troponin-I and BNP levels decreased to 0.30 ng/ml and 93 pg/ml, respectively.
DISCUSSION
Typically, ST elevation in myocardial infarction has a convex morphology in the leads corresponding to the affected coronary territory, with concomitant reciprocal ST-segment depression in the opposing leads [1]. Conversely, in pericarditis, ST elevation with a concave morphology is usually present in most leads, and involvement of the atria is responsible for depression of the PR segment [1,2]. In the present case, the initial ECG pattern was typical of ST-elevation myocardial infarction, and the pattern changed to that of typical pericarditis within 12 hours of the onset of symptoms. This might be due to focal myocarditis that caused myocardial ischemia with accompanying pericarditis, causing repolarization abnormalities. Cases with evidence of new-onset focal or diffuse reduction in left ventricular function with elevated myocardial biomarkers and the presence of clinical criteria for acute pericarditis can be diagnosed as predominant myocarditis with pericardial involvement, or “perimyocarditis” [3].
Although the gold standard for diagnosis of myocarditis is endomyocardial biopsy, it is not recommended in specific circumstances, such as new-onset heart failure with accompanying hemodynamic compromise [4,5]. If one or more clinical symptoms are present with elevated cardiac biomarkers and characteristic features on echocardiography or cardiac MRI, myocarditis can be diagnosed [6,7]. We could not confirm whether coronavirus OC43 was the causative agent; however, it was highly suspected because the serology results for other cardiotropic viruses and the respiratory viral panel were negative. The pathogenesis of cardiac involvement associated with coronavirus remains unknown. Further investigation is warranted to ascertain whether the coronavirus can replicate and disseminate through the lymphatic system from the respiratory tract, or if the secondary immune response to viral infection could play a role in disease pathogenesis rather than the primary infection [8].
Additionally, considering the underlying disease of the patient, differential diagnosis with cardiomyopathy is important. Among children with DMD, the incidence of cardiomyopathy increases steadily in the teenage years [9]. The pathology and cardiac MRI pattern of cardiomyopathy in patients with dystrophinopathy classically produce subepicardial fibrosis of the inferolateral wall, as observed in some patients with viral myocarditis. [10]. In our case, the cardiac dysfunction progressed rapidly and recovered quickly, suggesting a more acute course than that of cardiomyopathy. The common features of cardiomyopathy, such as ventricular dilatation, ventricular hypertrophy, or atrophy, were absent in this patient. Considering these factors, the diagnosis of acute perimyocarditis was more likely than that of cardiomyopathy, but this acute event could trigger earlier onset of cardiomyopathy in DMD.
In conclusion, patients with acute perimyocarditis can present with chest pain, focal ST-elevation, and significant elevation of cardiac enzymes, mimicking acute myocardial infarction. Differentiating between acute perimyocarditis and ST-elevation myocardial infarction is important because of differences in treatment strategies and prognoses. In the present case, the patient’s young age and preceding viral illness favored a diagnosis of acute perimyocarditis, and the normal coronary angiography eliminated the possibility of acute coronary syndrome.
XML Download