In developed countries, approximately what percentage of acute pericarditis cases are considered idiopathic or viral in origin?
Answer
85% to 90%
Explanation
The material states that **up to 90% of isolated acute pericarditis cases are idiopathic or viral**. This is useful when considering the cause of an otherwise isolated acute presentation, although clinicians must still assess for systemic disease and other specific causes. The lower percentage options underestimate the figure in the supplied lecture, while no claim is made that every isolated case has this cause. **Key takeaway:** Idiopathic or viral disease accounts for the great majority of isolated acute cases described in the material. **Glossary:** **Idiopathic**: without an identified cause. **Acute pericarditis**: recent inflammation of the pericardium.