Causes, Incidence and Risk Factors Endocarditis can involve the heart muscle , heart valves, or lining of the heart. 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. A history of congenital heart disease , intravenous drug use, or chronic localized abscess or infection, raises the index of suspicion. The examiner may detect a new heart murmur, or a change in a previous heart murmur. Examination of the nails may show splinter hemorrhages .