Most people who develop endocarditis have underlying heart disease .
Bacterial infection is the most common source of endocarditis.
However, it can also be caused by viruses, fungi, or other microorganisms. In some cases, no causative organism can be identified. Continued medical follow-up is advised for people with a previous history of endocarditis. The examiner may detect a new heart murmur, or a change in a previous heart murmur. Examination of the nails may show splinter hemorrhages .