Review Question - QID 217136

This patient with a respiratory viral prodrome (non-productive cough, malaise, myalgias, fever), chest pain, signs of heart failure (exercise intolerance, dyspnea at rest, tachypnea, tachycardia, hepatomegaly, and pitting edema of the lower extremities) most likely has viral myocarditis. In this patient without a history of rash or recent international travel, Coxsackie B virus is the most likely etiology.

Cardiotropic enteroviruses such as Coxsackie B virus are a common cause of viral myocarditis. Viral entry into the myocardium in susceptible individuals leads to both viral-mediated cell death and apoptosis. This may trigger activation of both the innate and acquired immune systems. The combination of these insults can lead to left ventricular dysfunction and signs of heart failure such as dyspnea, peripheral edema, and exercise intolerance. Initial evaluation for suspected viral myocarditis should include an electrocardiogram, cardiac biomarkers, natriuretic peptide levels, chest radiograph, and an echocardiogram. Endomyocardial biopsy (EMB) is the gold standard to confirm a clinical diagnosis of myocarditis; however, the complication rate is quite high. Cardiac magnetic resonance imaging (CMR) can be considered as an alternative to EMB. Diagnosis via CMR or EMB can help rule out other etiologies of acute heart failure including structural heart disease and cardiomyopathy due to other causes. Once a diagnosis of myocarditis has been made, viral culture or antibody titers should also be performed to determine the underlying etiology of myocarditis. Treatment usually includes nonspecific measures to treat the sequelae of heart disease such as with heart failure therapy.

Pollack et al. review the clinical presentation, diagnostic workup, and treatment options for viral myocarditis, including myocarditis secondary to Coxsackie B virus. The authors find that cardiac MRI and endomyocardial biopsy should be used to assist in the diagnosis of this disease. The authors recommend further investigation of immunosuppressive and immunomodulatory therapies for viral myocarditis.

Incorrect Answers:
Answer 1: Coxsackie A virus is an enterovirus that causes hand, foot, and mouth disease. This presents with vesicles or erythematous papules on the palms and soles, as well as herpangina (ulcers and vesicles in the oral mucosa). Coxsackie A virus is not cardiotropic and has not been reported to cause myocarditis.

Answer 3: Plasmodium falciparum is a protozoan that causes malaria. P. falciparum may cause myocarditis in rare cases. However, malaria has largely been eliminated from the United States, with approximately 2,000 cases per year. In this patient without a history of international travel, Coxsackie B virus is a more likely cause of myocarditis than P. falciparum.

Answer 4: Trypanosoma cruzi is a protozoan prevalent in South and Central America that causes Chagas disease. Acute infection with T. cruzi is usually asymptomatic, but may rarely present with nonspecific symptoms and swelling at the site of inoculation (including painless swelling around the eyelids if the conjunctiva is the site of inoculation). Severe acute disease occurs in less than 1% of patients but may manifest with acute myocarditis, pericardial effusion, and meningoencephalitis. Chronic T. cruzi infection can lead to megaesophagus and dilated cardiomyopathy.

Answer 5: Varicella zoster virus (VZV) may occasionally cause myocarditis as a severe complication. VZV infection usually presents with a characteristic dermatomal rash; however, in immunosuppressed patients, there may be disseminated infection without cutaneous disease. In this patient without a history of immunosuppression and without a preceding rash, Coxsackie B virus is a more likely cause of myocarditis than VZV.

Bullet Summary:
Coxsackie B virus is one of the most common causes of viral myocarditis, which presents with signs of heart failure after a viral prodrome.