Here’s another edition of Peds in a Pod courtesy of Dr. Melendez!
It’s that time of the year when all of the kids go back to school and the peds ED fills up because germs are now being spread from one child to the next, sneeze by sneeze, booger by booger. A majority of the time these kids will have some common viral illness but eventually there will be the sicker kid that comes in. This month’s blog looks into a common complaint in the peds ED that we often overlook and is meant to make you think just a little harder about whether or not to run some tests, get some labs or admit vs. discharge.
Scenario: It’s 4pm on a Monday and the waiting room is full. On the whiteboard you see several chief complaints of fever, vomiting, fall with lacerations but then you notice a new name on the board and the chief complaint is chest pain and fever in an 8 year old. The nurse triages the patient and she is febrile to 103, tachycardic to 130, tachypneic to 45 and O2 saturation is 93% RA. Her mother tells you that she started to have a viral URI 4 days ago but today she was c/o chest pain, was not eating and appeared to be very short of breath and not acting like herself. On her exam she is awake but very sleepy and not really interacting with you on exam. You hear a systolic murmur on your cardiac exam with muffled heart sounds, lung exam reveals crackles b/l at bases. Her CXR shows cardiomegaly with small pleural effusions b/l. You have myocarditis on your differential among some other diseases. What do you do?
This month’s topic is about viral myocarditis. Acute myocarditis has a wide spectrum of presentation: from mild flu-like symptoms, to acute cardiovascular collapse. Commonly, the disease course is progressive. The majority of the current literature on pediatric myocarditis consists of review articles, case reports, and retrospective studies.
Presentation
There is much overlap between the signs and symptoms of myocarditis and other common childhood illnesses. The saying “tachycardia out of proportion to the fever” is often quoted as a clinical “red flag” for myocarditis; however, this sign has minimal utility in an anxious child in the emergency department setting. Data on the clinical presentation of myocarditis in pediatrics patients come from retrospective reviews of presumed cases; therefore, they suffer from inaccuracies of documentation at the time of the original presentation. In a retrospective review of 41 adult patients with histologically- proven myocarditis, it was reported that the presenting signs and symptoms included congestive heart failure in 63%, atrioventricular block in 17%, chest pain in 15%, and supraventricular arrhythmias in 5%.
Diagnosis
Considerable debate remains about the criteria necessary to make a definitive diagnosis of myocarditis.
– Chest radiography and electrocardiography are frequently used when making management decisions in patients with suspected myocarditis. Although cardiomegaly and pleural effusions may be evident on chest radiography, they are not specific for myocarditis. The EKG often shows the non-specific finding of sinus tachycardia with low voltage QRS complexes (total QRS amplitude less than 5 mm in all precordial leads). Retrospective reviews have reported atrial arrhythmias, complete heart block and ventricular arrhythmias as well as findings consistent with acute MI in patients with myocarditis.
– Viral cultures of peripheral specimens such as blood, stool, or urine are commonly performed but are unreliable.
– Specimens from the blood, nasopharynx, and rectum should be sent for culture and PCR of common viruses. In addition, specimens from other sources such as the urine or trachea may be obtained if clinically indicated.
– Serum creatine kinase (CK-MB), and troponin I and T are routinely measured when myocarditis is suspected. Smith et al measured troponin I in a subgroup of 88 patients that had been enrolled in the Multicenter Myocarditis Treatment Trial. The sensitivity of an elevated troponin for the diagnosis of myocarditis was 0.34, the specificity was 0.89, and the positive predictive value was 82%.The authors concluded that an elevated troponin in a patient with unexplained heart failure, should suggest the possibility of myocarditis. This same study showed that there were no significant differences in CK-MB values between those with myocarditis and those without (p=.27) suggesting that CK-MB is not a useful general screening tool for myocarditis.
-Echocardiography is currently recommended as the initial diagnostic study for all patients with suspected myocarditis. Pinamonti et al retrospectively analyzed echocardiographic findings among 41 patients with biopsy proven myocarditis. Though left ventricular dysfunction occurred in 69%, significant left ventricular cavity enlargement was uncommon. Because these findings are similar to those from other forms of acute dilated cardiomyopathy, they are nonspecific for the diagnosis of myocarditis.
-Contrast enhanced magnetic resonance imaging (CE-MRI) appears to be the most promising non invasive imaging technique for identifying myocardial inflammation and myocyte injury in patients with presumed myocarditis. Friedrich et al used cardiac MRI to assess 44 patients with symptoms of acute myocarditis and compared the findings to 18 control patients. With serial evaluation by CE-MRI during the first 2 weeks of illness, they were able to localize and determine the extent of inflammation in the study patients.
-Although it is still probably considered the gold standard, endomyocardial biopsy is reserved for patients who have an acute deterioration of cardiac function of unknown etiology and who are unresponsive to medical therapy.
-BNP is still being investigated
Treatment
– The routine use of immunosuppressive therapy for patients with myocarditis is not recommended. This recommendation exists as part of published treatment guidelines from the HFSA and is based on expert consensus opinion. Although immunosuppressive agents may be beneficial in patients with myocarditis secondary to systemic auto-immune diseases such as lupus erythematosus and scleroderma
– Routine use of immunoglobulin is also not recommended for patients with myocarditis.
Guidelines exist from the HFSA that state that intravenous immunoglobulin (IVIG) therapy does not provide benefit to patients with new onset cardiomyopathy and myocarditis. A Cochrane analysis also concluded that there was no convincing evidence supporting the use of IVIG for the treatment of presumed viral myocarditis. This conclusion was largely based on a paucity of well-designed studies. The author did note that there were multiple case reports and case series reporting dramatic responses to IVIG in adults and children with acute myocarditis.
-There are no randomized clinical trials directly assessing the efficacy of antiviral therapy in the treatment of myocarditis. There are several case reports commenting on the benefits of ganciclovir therapy in viral associated myocarditis. There are also several clinical trials using interferon beta that have demonstrated beneficial effects.
-Finally, attenuated vaccines have been used to prevent the development of myocarditis after viral challenge in animals. However, the usefulness of vaccines in humans remains unclear.
– Arrhythmia management includes the use of pharmacologic therapy or cardioversion as appropriate for tachyarrhythmias. In the case of atrioventricular block with a bradycardic escape rhythm, transcutaneous or transvenous pacing may be required.
-For patients presenting in congestive heart failure, management should be directed by the HFSA guidelines with loop diuretics, IV vasodilators and diuretics and IV inotropes.
Conclusion
With variable presentation patterns, intricate pathobiology and unproven therapeutic options, acute myocarditis remains an enigmatic disease. In the future, further definition of the cellular level processes and genetic factors that determine the clinical phenotype
of individual acute heart failure patients may allow for specific therapeutic targets in certain patient populations. However, in the current era, therapeutic options remain generalized and largely supportive in nature.
References
Pinamonti B, Alberti E, Cigalotto A, Dreas L, Salvi A, Silvestri F,
Camerini F. Echocardiographic findings in myocarditis. Am J
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Heart Failure Society Of Americamerica: Evaluation and management
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Angelini A, Calzolari V, Calabrese F, Boffa GM, Maddalena F,
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infarction: role of endomyocardial biopsy in the differential diagnosis.
Heart (British Cardiac Society) 2000;84(3):245-250.
Smith SC, Ladenson JH, Mason JW, Jaffe AS: Elevations of cardiac
troponin I associated with myocarditis. Experimental and clinical
correlates. Circulation. 1997;95(1):163-168. (Retrospective review;
88 patients)
Parrillo JE, Cunnion RE, Epstein SE, Parker MM, Suffredini AF,
Brenner M, et al: A prospective, randomized, controlled trial of
prednisone for dilated cardiomyopathy. N Engl J Med.
1989;321(16):1061-1068. (Prospective randomized trial; 102
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Mason JW, O’Connell JB, Herskowitz A, Rose NR, McManus BM,
Billingham ME, et al: A clinical trial of immunosuppressive therapy
for myocarditis. The Myocarditis Treatment Trial Investigators.
N Engl J Med. 1995;333(5):269-275. (Prospective, randomized trial;
111 patients)
Bowles NE, Kearney DL, Ni J, Perez-Atayde AR, Kline MW,
Bricker JT, et al: The detection of viral genomes by polymerase
chain reaction in the myocardium of pediatric patients with
advanced HIV disease. J Am Coll Cardiol. 1999;34(3):857-865.
(Descriptive histological study; 64 patients)
Drucker NA, Colan SD, Lewis AB, Beiser AS, Wessel DL, Takahashi
M, et al: Gamma-globulin treatment of acute myocarditis in the
pediatric population. Circulation. 1994;89(1):252-257. (Retrospective
case control study; 21 patients)
McNamara DM, Rosenblum WD, Janosko KM, Trost MK,
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Jay Khadpe MD
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