Aetiology
The causes of acute pericarditis are widespread and are listed in Table 1:
| Idiopathic | Most likely to be viral in origin |
| Viral e.g. Echovirus Enterovirus Cocksackie CMV (immunocompromised patients) Hep B Infectious mononucleosis HIV |
|
| Bacterial e.g. Pneumococcus Staphylococcus Streptococcus Mycoplasma |
Characterised by purulent effusion. Commonest cause is by direct extension from a pneumonia or empyema |
| Tuberculous | 1-8% of patients with pulmonary TB. Characterised by a more indolent course and non-specific features of fever, malaise and dyspnoea [5] |
| Post Acute Myocardial Infarction | Early (1-3 days): transmural necrosis causing adjacent pericarditis Late (1 week to a few months): Dressler’s Syndrome (autoimmune) |
| Trauma / Post Cardiac Surgery | Blunt or penetrating injury |
| Neoplastic | Predominantly from secondary metastatic tumours |
| Uraemia | Pathophysiology unknown |
| Inflammatory/ Autoimmune | Rheumatoid arthritis SLE: the most common cardiac manifestation (40 % patients with SLE get pericarditis at some time5) Scleroderma |
| Following chest wall irradiation | Early: acute illness Late: can occur years after exposure |
| Drug induced | Isoniazid Hydralazine |
Most cases are ‘idiopathic’ (80-90%) [5]. Although labelled as idiopathic, the majority of these are likely to be viral in origin, but viral testing is not routinely done as it rarely alters the management and is not cost-effective.
The incidence of viral pericarditis is higher in young previously healthy adults and is lower in those patients who are subsequently found to need inpatient management. Patients with tuberculous pericarditis present with a less acute course. Patients with bacterial pericarditis present more acutely unwell and with other features of bacterial sepsis.
Learning bite
Most cases of acute pericarditis in developed countries are based on viral infections which are self-limiting, with most patient recovering without complications.