Acute pericarditis is an inflammatory condition involving pericardium and is responsible for 0.2% of all cardiovascular hospitalization [1]. Almost the whole acute pericarditis (80–90%) are idiopathic in developed countries, suggesting a viral etiology, roughly 70–90% are self-limiting while only 5% are therapy-resistant [2, 3]. Among viral pathogens enteroviruses, herperviruses, parvovirus B19, cytomegalovirus, H1N1, parainfluenza, varicella zoster, HIV, hepatitis B and C are listed; bacterial, fungal, and parasitic infections are rare [4, 5]. Neoplastic, systemic inflammatory syndromes-related, tuberculosis, and purulent pericarditis occurred respectively in 5–10%, 2–27%, 4%, and < 1% of cases [5]. Diagnosis of pericarditis is made by the presence of at least 2 of the following criteria: acute chest or pleuritic pain, pericardial friction rubs, electrocardiogram (ECG)-specific alterations, and evidence of new or worsening pericardial effusion. Among additional criteria, C-reactive protein (CRP) elevation, present in 75% of cases [6], and evidence of pericardial inflammation on computed tomography (CT) or magnetic resonance image are included.
To date, no case of Influenza B virus infection-related pericarditis, without myocardial involvement, has been described. We report this first case of life-threatening pericarditis due to Influenza B virus infection.
Case presentation
A 48-years-old woman with trisomy 21 and history of ostium primum atrial septal defect and hypothyroidism, on effective replacement therapy, was transferred from the Cardiology of another hospital to our Internal Medicine Department because of dyspnea with acute and worsening respiratory failure. She had been in her usual health until 2 months before admission, when a flu-like syndrome occurred in November. After 15 days, during an admission in other hospital for syncope with sphincter incontinence, a mild pericardial effusion (7 mm) was diagnosed and treated with ibuprofen 600 mg every 8 h and colchicine 0.5 mg twice day. Two weeks later, due to worsening of dyspnea and appearance of diarrhea, therapy had to be suspended. Trans-thoracic echocardiogram showed a diffuse increase in pericardial effusion (30 mm) without inspiratory collapse of the inferior vena cava (Fig. 1a). Chest CT confirmed massive pericardial effusion and highlighted bilateral basal and left upper lobe pleural effusion with atelectasis. Therefore, a metilprednisolone 60 mg/day (1 mg/Kg) and furosemide 40 mg/day therapy was started.
On admission, blood pressure was 110/70 mmHg, heart rate 75 beats per minute, respiratory rate 16 breaths per minute, body temperature 99 °F, and oxygen saturation 86% while the patient was breathing ambient air. Cardiac examination revealed muffled heart sounds and a 3/6 ejection murmur on aortic area. Pulmonary evaluation revealed a stony dull percussion with diminished vesicular breath sounds on basal region bilaterally and widespread rhonchi. The total leukocyte count was 8400/μL (neutrophils 93% and lymphocytes 15%), erythrocyte sedimentation rate (ESR) 120 mm/h, CRP 16 mg/L, procalcitonin 0.05 ng/mL, MR-pro-adrenomedullin 0.96 nmol/L, ferritin 3799 ng/mL, NT-proBNP 254 pg/mL, and TSH 0.33 mcU/L; ANA, anti-dsDNA, ENA, c-ANCA and p-ANCA were in the normal range. Arterial blood gas analysis revealed severe hypoxemia with respiratory and metabolic alkalosis (pH 7.48, pO2 47.3 mmHg, pCO2 36.1 mmHg, HCO3− 26.6 mmol/l). ECG highlighted incomplete right bundle branch block, while trans-thoracic echocardiogram showed large circumferential pericardial effusion (25, 23, and 30 mm respectively on apical, posterior, and lateral ventricular walls, 20 mm on right ventricular wall) without right ventricular compression; grade 2 diastolic dysfunction; mild left-right shunt due to ostium primum atrial septal defect; mild tricuspidal and minimal mitral regurgitations with cleft of the anterior mitral valve leaflet; mild enlargement of the right cardiac chamber with pulmonary artery pressure of 40 mmHg. Chest X-ray showed widespread bronchial wall thickening and enlargement of the cardiac silhouette (Fig. 2).
The absence of other causes for pericardial effusion and the history of recent flu-like syndrome rose the suspicion of a viral etiology; therefore, laboratory evaluation identified the presence of influenza B virus on molecular assay of tracheal aspirate. Antiviral therapy with oseltamivir 75 mg twice a day for 5 days was added to ongoing treatment with metilprednisolone 30 mg (0.5 mg/kg/day) and colchicine 0.5 mg/day therapy [7].
The patient showed a progressive clinical and CRP improvement with disappearance of the pericardial effusion on 15-days echocardiographic follow-up.
The patient was discharged in good medical conditions with 1-month prednisone 30 mg/day followed by dose reduction of 2.5 mg every 5 days and 3-months colchicine 0.5 mg/day therapy [7].
At 1-month follow-up, patient was asymptomatic with normal physical examination, CRP 1.1 mg/L, and echocardiogram showed mild pericardial detachment on right atrium without sign of compression (Fig. 1b). At 6-month follow-up, clinical and echocardiographic features was preserved, with complete normalization of inflammatory markers (CRP 0,26 mg/L) even when treatment was suspended.