Influenza Type B Complicates a Previously Undiagnosed Case of Pericarditis

Abstract

We report the first case of pericarditis exacerbation due to influenza B viral infection while emphasizing the importance of cardiac magnetic resonance (CMR) for the timely diagnosis and ruling out of non-effusive pericarditis in a patient with compatible, unexplained chest pain. The patient presented with left-sided chest pain that was partially relieved by leaning backward and noted persistent fatigue for several days. Pericardial friction rub, electrocardiogram (ECG), and echocardiogram abnormalities were not detected. After discharge on the morning following admission, fatigue and fever several minutes after physical exertion continued. The patient contracted influenza type B, leading to pneumonia and a second hospitalization, during which echocardiography showed moderate pericardial effusion. We conclude that the patient had pericarditis on the first admission because other compatible causes of chest pain were ruled out, symptoms were compatible with non-effusive pericarditis and could not be ruled out since CMR was not done, and the patient tested positive during his second admission for multiple known etiologic agents of pericarditis. We highlight the importance of CMR in screening patients presenting with chest pain of unknown origin to facilitate early detection and intervention.

Keywords: differential diagnosis of acute chest pain; echocardiogram (echo); infectious pericarditis; influenza b; missed case of pericarditis; non-effusive pericarditis; pericarditis.

Figure 1. Chest X-ray of the patient during the first admission

Note the absence of cardiopulmonary processes

Figure 2. Chest X-ray of the patient during the second admission

Lower left lobe infiltrates and minor pleural effusion (arrows) are seen. An enlarged cardiac silhouette is indicated by a cardiothoracic ratio of 0.6.

Figure 3. Echocardiography (A) and computed tomography (B) images taken on day one of the second admission.

Pericardial effusion is evident in both echocardiography (white arrows) and computed tomography (black arrows).

Figure 4. Chest X-ray of the patient on day three of the second admission

Pericarditis with a water bottle sign (highlighted), left pleural effusion (arrow), left lower lobe pneumonia, and right lower lobe atelectasis (arrowheads) are seen.