A 25-year-old man with no significant past medical history presented with persistent fever and nonproductive cough of two-week duration. His symptoms were initially treated as an outpatient one week prior to presentation with amoxicillin/clavulanic acid due to concern for pneumonia; however, his symptoms progressively worsened. Upon presentation, his initial vital signs were as follows: T: 100.8, P: 108, BP: 120/73, RR: 20, and oxygen saturation: 95% on room air. Within 24 hours he developed increased oxygen requirements requiring three liters of supplemental oxygen, orthopnea, and voluminous blood-tinged, frothy sputum. Physical examination was remarkable for mild respiratory distress and diminished heart and lung sounds. Initial basic metabolic panel and complete blood count were normal. NTproBNP was elevated at 513, troponin-t was elevated at 0.04, and inflammatory markers were elevated (ESR 55, CRP 13.4). Respiratory viral reverse transcriptase polymerase chain reaction (PCR) was positive only for hMPV using a nasopharyngeal swab. Chest X-ray showed new cardiomegaly and bilateral opacities, as compared to a normal chest X-ray 6 months earlier, suggesting pulmonary edema. Our differential diagnosis at this point included acute heart failure, pulmonary infection, and diffuse alveolar haemorrhage. Pulmonary medicine was consulted and a computed tomography (CT) of the chest demonstrated bilateral opacities. Echocardiogram demonstrated a severely depressed ejection fraction of 25% with severely enlarged left atrial volume and severely dilated left ventricle. Cardiac magnetic resonance imaging (MRI) showed septal wall enhancement compatible with myocarditis (Figure 1). The patient was transferred to the cardiac intensive care unit and started on intravenous diuretics and afterload and preload reducing agents (furosemide 80 mg IV BID, captopril 3.125 mg TID, metoprolol tartrate 12.5 mg BID, and isosorbide dinitrate 10 mg TID). Over the course of seven days the patient improved. He was net negative eight liters from admission and was discharged home on lisinopril 5 mg and metoprolol succinate 25 mg daily.
On hospital day 4, the national reference laboratory's report of respiratory pathogen testing of a nasal swab collected on admission was positive for hMPV but negative for pathogens most commonly causing pulmonary infection, including influenza A and influenza B, parainfluenza, respiratory syncytial virus, adenovirus, tuberculosis, and mycoplasma.