Case of the Month – April 2017 – Answer

Both of this month’s responses hit the diagnosis square on the head: Dr. Schnitzer’s succinct reply with the differential, work-up, and disposition, and Dr. Hernandez’s expanded (and entertaining) discussion.

Click here to review the case.

A quick recap:

A 15 year-old boy presents with chest pain, decreased oral intake, cough, and fatigue in the setting of a recent upper respiratory infection. He is found to be febrile, tachycardic, and in respiratory distress on exam. Labs show leukocytosis; ECG demonstrates decreased voltage, and CXR with bilateral pleural effusions.

 

What is in the differential diagnosis?  What diagnosis is most likely and which is less likely?

The chest pain, shortness of breath, fatigue (worsening dyspnea?) with exertion, and the time-course are all clues that he is suffering from symptoms of acute heart failure. The presence of sinus tachycardia and low voltage QRS complexes are also additional clues. In a pediatric patient, this raises the possibility of a structural or congenital heart defect, idiopathic dilated cardiomyopathy, or an intrinsic cardiac infection such as myocarditis, endocarditis, and pericarditis. However, as Drs. Schnitzer and Hernandez noted, he could be suffering from Rheumatic fever, or, as Dr. Schnitzer’s work-up correctly alluded to, his symptoms could be a result of severe sepsis from an alternate infection

The key here is to always have a high index of suspicion. This case had several clues pointing towards acute heart failure, but patients can present with such non-specific symptoms as fever, lethargy, decreased PO intake, lethargy, pallor, dyspnea, chest pain, or even abdominal pain. Given how non-specific the symptoms can be, myocarditis is often initially misdiagnosed and may require numerous evaluations by a healthcare provider before being definitively identified. Ultimately, myocarditis is a clinical diagnosis and then is either supported or refuted by additional testing.

 

What further tests would you do?

In the ED, laboratory tests like cardiac enzymes and BNP may be helpful with differentiating myocarditis from dilated cardiomyopathy. But, troponin T only has a sensitivity of 71% for myocarditis in pediatric patients with limited data supporting a cut-off of 0.052 ng/mL.2

A bedside echo can be helpful with characterizing the contractility, the presence or absence of wall motion abnormalities, or valvular dysfunction, though again, there are no echocardiographic findings that are specific to myocarditis.

However, the greatest utility of the echo is the differentiation between acute and fulminant myocarditis. In acute myocarditis, the patient will demonstrate decreased wall motion and EF; in fulminant myocarditis (often with symptoms of cardiogenic shock), the left ventricle will demonstrate normal diastolic dimensions and increased septal thickness. Differentiating between the two may confer some prognostic value; counterintuitively, patients with fulminant myocarditis have better long-term prognosis. This may be due to their presentation being more obvious, so that they receive more rapid/aggressive care.

Obviously, sending autoimmune markers and anti-Streptolysin O could clue you in as to the etiology of the patient’s myocarditis, and blood cultures would clue you in to whether or not the patient’s symptoms are simply due to severe sepsis, but these won’t come back while he is in the ED.

According to the textbooks, the gold standard for diagnosis is still an endomyocardial biopsy, but this is beyond ED management and can produce false negatives if the biopsied portion does not happen to be inflamed. Cardiac MRI has been shown to increase the sensitivity of a biopsy when used as an adjunct to identify areas of inflammation to guide the biopsy.

 

What is your therapeutic plan?

The same as the therapeutic plan for every patient: ABCs, IV, O2 (for hypoxemia), monitor….

Seriously though, the key is to treat any dysrhythmias and provide cardiac support. Medications may include inotropic/vasopressor agents and general heart failure medications (diuretics, aldosterone inhibitors, afterload reducing agents). Until the definitive diagnosis is identified, start broad-spectrum antibiotics to account for severe sepsis. Consider intubation and mechanical ventilation depending on the patient’s clinical picture, as it may reduce his work of breathing and overall metabolic demands. Immunomodulating drugs such as steroids or IVIG have also been tested as adjunctive therapies for myocarditis. A Cochrane review from 2013 demonstrated LVEF improvement with corticosteroid therapy in viral myocarditis, particularly with analysis of a pediatric subgroup, but the trials were deemed low-quality, and results were thus inconclusive. Similarly, the data is limited for the use of IVIG. One study6 involving 46 patients (21 receiving IVIG and 25 controls) suggesting improved survival over 1 year, and another study7 involving 216 patients showed no survival benefit.

 

What is the ultimate disposition for this patient?

At the very least, the patient warrants a cardiac consultation and admission to the PICU, but given the severity of his symptoms, he may ultimately benefit from transferring to a facility with the capability to perform ECMO or cardiac transplantation.

 

References

  1. Allan, Catherine, and David Fulton. “Treatment and Prognosis of Myocarditis in children.”  09 March 2017. Uptodate. Web
  2. Durani, Yamini; Giordano, Katie, and Brett Goudie. “Myocarditis and Pericarditis in Children.” Pediatric Clinics of North America.  57:6, 1281-1303, December 2010
  3. Quiñones, Casandra, and Beth Bubolz. “Cardiac Emergencies.” Fleisher & Ludwig’s Textbook of Pediatric Emergency Medicine. Philadelphia: Lippincott Williams, 2016. 651. Print.
  4. Allen, Catherine, and David Fulton. “Clinical manifestations and diagnosis of myocarditis in children.” Uptodate. N.p., 23 Nov. 2015. Web.
  5. Chen HS, Wang W, Wu SN, Liu JP. “Corticosteroids for viral myocarditis.” Cochrane Database Syst Rev. 2013;
  6. Drucker NA, Colan SD, et Al. “Gamma-globulin treatment of acute myocarditis in the pediatric population.” Circulation. 1994;89(1):252.
  7. Klugman D, Berger JT, et Al. “Pediatric patients hospitalized with myocarditis: a multi-institutional analysis.”  Pediatric Cardiology.  2010; 31(2):222

 

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rithvikb

Resident Physician, EM/IM  

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