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Year : 2019  |  Volume : 10  |  Issue : 2  |  Page : 86-88

Dilated cardiomyopathy following H1N1 infection

Department of Paediatrics, Father Muller Medical College Hospital, Mangalore, Karnataka, India

Date of Web Publication24-Jan-2020

Correspondence Address:
Dr. Sweta Shanbhag
“Avalon,” Flat Number 001, Near Souza Nivas, Monkey Stand New Road, Mangalore - 575 001, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjmsr.mjmsr_40_19

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Acute myocarditis and dilated cardiomyopathy are known to be common manifestations of several viral infections, presenting with a wide spectrum of symptoms. The exact pathogenesis of influenza virus-induced myocarditis is still unclear. Management involves early detection using echocardiography and cardiac support to tide over acute phase. Following recovery, prognosis is known to be quite good; however, fulminant cases have poor prognosis. A 2-year-old female infant previously diagnosed to have H1N1 bronchopneumonia a year back, who was found to have compromised cardiac function suggestive of dilated cardiomyopathy on follow-up and was started on oral antifailure medications and kept on regular follow-up, presented to the emergency department with symptoms suggestive of severe form of dilated cardiomyopathy and succumbed to illness. The association between influenza viral infection and myocarditis is being linked with host immune response as well as direct cellular damage. Vaccination is being said to be the most cost-effective strategy to prevent this potentially fatal complication. Recent-onset cardiac symptomatology with a preceding history suggestive of influenza infection warrants a high index of suspicion for myocarditis and dilated cardiomyopathy. Early detection and prompt cardiac supportive care and management are paramount and help to reduce morbidity and mortality.

Keywords: Dilated cardiomyopathy, echocardiography, H1N1 influenza A, myocarditis

How to cite this article:
Shanbhag S, Alva R, Avabratha K S. Dilated cardiomyopathy following H1N1 infection. Muller J Med Sci Res 2019;10:86-8

How to cite this URL:
Shanbhag S, Alva R, Avabratha K S. Dilated cardiomyopathy following H1N1 infection. Muller J Med Sci Res [serial online] 2019 [cited 2023 May 28];10:86-8. Available from: https://www.mjmsr.net/text.asp?2019/10/2/86/276690

  Introduction Top

Viral infections are the most common causes for myocarditis and dilated cardiomyopathy, other causes being medications, toxins, autoimmune disorders, and other infections.[1] Viral pathogens or cardiotropic viruses,[1] commonly associated with myocarditis, include coxsackievirus, adenovirus, and very rarely influenza viruses.[2] Postinfluenza myocarditis prevalence is reported to range between 0% and 11%, depending upon the criteria used to define myocarditis and dilated cardiomyopathy.[3] As the immune responses are limited in children, viral invasion and spread to tissues may be of concern.[4] Literature review suggests that myocarditis prevalence with pandemic strains is documented in fatal cases, with 39.4% for 1957 Asian pandemic and 48% for Spanish flu pandemic.[2] Acute deaths and isolated presenting symptom of myocarditis postinfluenza in children are rare; it can lead to dilated cardiomyopathy and sudden death in the young, making it a diagnosis of concern for clinicians.[4]

  Case Report Top

A 2-year-old female infant was brought to the emergency department with acute cardiorespiratory distress, cyanosis, hepatomegaly, and severe metabolic acidosis. Chest X-ray showed cardiomegaly. Echocardiography showed severe left ventricular dysfunction with ejection fraction of 10%–15%. The child succumbed to the illness within 6 h of admission.

At 1 year of age, this child was diagnosed to have H1N1 bronchopneumonia (proven by polymerase chain reaction). She had shown clinical improvement with specific antiviral therapy [Figure 1]. She was thereafter discharged. Following that, she had made two outpatient visits, had no fresh complaints [Figure 2], and was thought to have completely recovered. After around 2 months, she was brought with an acute history of fever, cough, coryza, and vomiting. On examination, she had nasal flaring, tachypnea and chest retractions with bilateral rhonchi, and crepitations, however maintaining saturation at room air.
Figure 1: Bronchopneumonia

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Figure 2: Normal chest X-ray showing resolved bronchopneumonia

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Basic blood investigations showed an elevated C-reactive protein and dimorphic anemia. She was started on intravenous (IV) antibiotics, bronchodilator nebulization, and oral antipyretics. Chest X-ray showed cardiomegaly [Figure 3] with bilateral haziness in the lung fields. Echocardiography showed moderate mitral regurgitation, dilated left atrium and ventricle accompanied by hypokinesia, and severe dysfunction of the left ventricle with a left ventricular ejection fraction of 15%–20% and a well-maintained right ventricular function.
Figure 3: Cardiomegaly

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Considering it to be dilated cardiomyopathy secondary to probable H1N1 myocarditis, few investigations were done to rule out probable secondary causes. Thyroid function tests, serum electrolytes, and troponin T were normal; CKMB was slightly elevated.

Treatment was started with inotropes, diuretics, enalapril, oral prednisolone, L-carnitine, and calcium supplements. A 5-day course of oral antiviral therapy (oseltamivir) was repeated despite repeat throat swab for H1N1 being negative. After a week of treatment, the child showed clinical improvement; hence, inotropes and IV antibiotic were stopped, all other IV medications changed to oral, and echocardiography was repeated. The findings and left ventricular ejection fraction continued to remain the same in spite of obvious clinical improvement. The child was started on oral antiplatelet drug to prevent thrombosis and discharged with the advice to continue all other ongoing medications. On the next visit to the outpatient department after 1 month, echocardiography showed slight improvement in the left ventricular ejection fraction to 20%–25%, but other parameters remained the same and advised to continue the same medications and review after 3 months for a repeat echocardiography; however, after that, the child was lost to follow-up until the present admission.

  Discussion Top

First association between influenza and myocarditis was seen with 1918 Spanish influenza pandemic and was based on autopsy studies.[1] Mechanisms involved with influenza myocarditis is unclear and is believed to be linked with host immune response as well as direct cytolysis postviral infection.[5] Vaccination is supposedly the most cost-effective strategy as oseltamavir has shown little impact on progression of combined pneumonitis and myocarditis.[4] Disease course can vary from being either inapparent or fatal with 28% mortality in myocarditis patients.[1]

  Conclusion Top

H1N1 influenza viral infection should be considered as one of the etiologies of myocarditis and dilated cardiomyopathy as its incidence is now on the rise. Timely echocardiography helps in early detection and prompt treatment with specific antiviral therapy, as well as supportive cardiac management, mainly hemodynamic and ventilator support to tide over the acute cardiac crisis may have favorable outcome. Patients who survive the acute phase usually show a favorable long-term prognosis with good recovery of cardiac function.


We would like to acknowledge Dr. Prem Alva (Pediatric Cardiologist), all the pediatric residents, and nursing staff involved in the care of the patient.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's mother has given her consent for her images and other clinical information to be reported in the journal. The patient's mother understands that her name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.D

  References Top

Geladari EV, Vallianou NG, Kratimenos TH, Trigkidis K, Kokkinakis E. Myocarditis due to influenza B virus: The importance of early antiviral therapy. J Cardiol Clin Res 2016;4:1079.  Back to cited text no. 1
Ukimura A, Satomi H, Ooi Y, Kanzaki Y. Myocarditis associated with influenza A H1N1 pdm2009. Hindawi Publishing Corporation Influenza Research and treatment; 2012.  Back to cited text no. 2
Lobo ML, Taguchi Â, Gaspar HA, Ferranti JF, de Carvalho WB, Delgado AF. Fulminant myocarditis associated with the H1N1 influenza virus: case report and literature review. Rev Bras Ter Intensiva 2014;26:321-6.  Back to cited text no. 3
Tremlet W, Michie CA, Newsom D. Myocarditis in a fatal case of H1N1 influenza. West Lond Med J 2009;1:1-4.  Back to cited text no. 4
Cabral M, Brito MJ, Conde M, Oliveira M, Ferreira GC. Fulminant myocarditis associated with pandemic H1N1 influenza A virus. Rev Port Cardiol 2012;31:517-20.  Back to cited text no. 5


  [Figure 1], [Figure 2], [Figure 3]


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