A 32-year-old woman comes to the clinic due to progressively worsening dyspnea a month after returning from a vacation in Texas. The symptoms started with shortness of breath on exertion and have progressed to the point that she now wakes during the night with a choking sensation that improves only with sitting up. The patient has had a very active lifestyle for years, but currently she is markedly limited in her activities. She has no associated chest pain, skin rash, or joint pain. The patient has no significant medical history. Family history is significant for thyroid cancer in her aunt and lung cancer in her father. There is no family history of coronary artery disease, heart failure, or sudden cardiac death. She does not use illicit drugs. The patient currently lives in New York City. Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 96/min, and respirations are 14/min. Bilateral pitting ankle edema is present. The liver is enlarged 2 cm below the right costal margin. Lung auscultation reveals decreased breath sounds at the bases bilaterally. Cardiac examination reveals the presence of a third heart sound. Chest x-ray reveals an enlarged cardiac silhouette and small bilateral pleural effusions. ECG shows nonspecific ST segment changes. Which of the following is the most likely cause of this patient's symptoms?

Question

A 32-year-old woman comes to the clinic due to progressively worsening dyspnea a month after returning from a vacation in Texas.  The symptoms started with shortness of breath on exertion and have progressed to the point that she now wakes during the night with a choking sensation that improves only with sitting up.  The patient has had a very active lifestyle for years, but currently she is markedly limited in her activities.  She has no associated chest pain, skin rash, or joint pain.  The patient has no significant medical history.  Family history is significant for thyroid cancer in her aunt and lung cancer in her father.  There is no family history of coronary artery disease, heart failure, or sudden cardiac death.  She does not use illicit drugs.  The patient currently lives in New York City.  Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, pulse is 96/min, and respirations are 14/min.  Bilateral pitting ankle edema is present.  The liver is enlarged 2 cm below the right costal margin.  Lung auscultation reveals decreased breath sounds at the bases bilaterally.  Cardiac examination reveals the presence of a third heart sound.  Chest x-ray reveals an enlarged cardiac silhouette and small bilateral pleural effusions.  ECG shows nonspecific ST segment changes.  Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d349_ab40_bc81_e711f342b33d_MD0003_00 This patient has dilated cardiomyopathy (DCM) that is most likely due to viral myocarditis. A number of viruses have been implicated in DCM, including parvovirus B19, human herpes virus 6, coxsackievirus, adenovirus, influenza virus, and HIV. It is thought that an initially inadequate immune response to a viral infection allows the virus to invade cardiac myocytes, leading to cytotoxicity and impaired contractile function. Decreased systolic function and ventricular dilation (eccentric hypertrophy) ensue. Viral myocarditis most commonly affects relatively young adults (eg, age <55), and patients typically present with DCM and signs and symptoms of decompensated heart failure. Less commonly, patients will not develop DCM but will present with chest pain that can mimic myocardial infarction. Sudden cardiac death is rare but can occur. Many, but not all, patients will describe several weeks of viral prodrome (eg, fever, malaise, myalgias) that precedes the development of cardiac symptoms. ECG typically shows nonspecific ST segment changes, and echocardiogram shows 4-chamber dilation (in the setting of DCM). Endomyocardial biopsy aided by viral polymerase chain reaction is the diagnostic gold standard, but diagnosis is often assisted by noninvasive cardiac MRI. (Choice A) Coronary atherosclerosis is a common cause of DCM and heart failure in patients age >45. It is unlikely in this young woman with no significant risk factors for coronary artery disease (eg, family history, hypertension). (Choice B) Coccidioidomycosis typically manifests with symptoms similar to community-acquired pneumonia (eg, fatigue, cough, fever). It is endemic in the southwestern United States, including parts of Texas; however, it does not typically cause myocarditis or heart failure. (Choice C) Connective tissue disorders (eg, systemic lupus erythematosus, rheumatoid arthritis) are a rare cause of DCM. Absence of skin rash or joint pains makes an underlying connective tissue disorder unlikely. (Choice D) Severe hypothyroidism can rarely cause DCM but is less likely than viral myocarditis in the absence of associated signs and symptoms of hypothyroidism (eg, cold intolerance, constipation, dry skin). (Choice E) Lyme disease with cardiac involvement (Lyme carditis) usually presents with conduction abnormalities (eg, atrioventricular block), and DCM would be an uncommon manifestation. Absence of conduction abnormality on ECG makes Lyme carditis unlikely. Educational objective: Viral myocarditis is a common cause of dilated cardiomyopathy in relatively young adults. Patients typically present with signs and symptoms of decompensated heart failure (eg, dyspnea, orthopnea, peripheral edema). References: Viral myocarditis--diagnosis, treatment options, and current controversies. (http://www.ncbi.nlm.nih.gov/pubmed/26194549) Myocarditis. (http://www.ncbi.nlm.nih.gov/pubmed/22185868) The diagnosis and evaluation of dilated cardiomyopathy. (http://www.ncbi.nlm.nih.gov/pubmed/27339497)

A 32-Year-Old Woman Comes to the Clinic Due to Progressively