Symptoms of Infective Endocarditis
Fever is the most common presenting symptom of infective endocarditis, occurring in the majority of acute cases, though it may be absent in subacute presentations 1. The clinical presentation is highly variable and can be organized into three categories: nonspecific systemic symptoms, cardiac manifestations, and embolic phenomena 2.
Nonspecific Systemic Symptoms
The constitutional symptoms include:
- Fever (most frequent)
- Chills and night sweats
- Anorexia and weight loss
- Malaise and fatigue
- Myalgias
- Back pain 3
These symptoms are often vague and can mimic other systemic illnesses, making the diagnosis challenging. The classical "fever of unknown origin" presentation now represents only a minority of cases 2.
Cardiac Manifestations
A new or worsening heart murmur is a typical cardiac feature 1, though its absence does not exclude the diagnosis 4. Cardiac symptoms include:
- Heart failure (42-60% of cases, most common complication) - caused by acute valvular regurgitation, obstruction, or fistula formation 5
- New or changing murmur on auscultation
- Symptoms of valvular dysfunction (dyspnea, orthopnea)
- Acute respiratory failure from cardiogenic pulmonary edema (can mimic ARDS) 4
Heart failure is more common when the aortic valve is affected rather than the mitral valve 5.
Peripheral and Embolic Manifestations
Classic peripheral stigmata, though now rarely seen in high-income settings, include 6:
- Petechiae (search carefully for these)
- Osler's nodes (painful nodules on finger/toe pads)
- Janeway lesions (painless hemorrhagic macules on palms/soles)
- Splinter hemorrhages (under nails)
- Roth's spots (retinal hemorrhages with pale centers on funduscopic exam)
Embolic phenomena can present as:
- Neurological complications (stroke, cerebral abscess)
- Splenic infarction/abscess
- Renal complications (hematuria, nephritis)
- Pulmonary emboli (in right-sided endocarditis)
- Peripheral vascular events 3, 7
Critical Clinical Pitfalls
The absence of fever, murmur, or peripheral stigmata on initial examination does not exclude infective endocarditis 4. Patients can present with isolated respiratory failure, unexplained sepsis, or organ-specific complications without obvious cardiac signs initially. Daily cardiac auscultation and funduscopic examination are essential in suspected cases 3.
Splenomegaly should be actively sought on physical examination 3. Laboratory findings typically show anemia, elevated erythrocyte sedimentation rate, and urinary abnormalities compatible with nephritis or embolization 3.
The diagnosis requires high clinical suspicion in any patient with unexplained fever or sepsis, particularly those with risk factors including prosthetic valves, structural heart disease, intravenous drug use, or recent invasive procedures 8. When suspected, obtain at least three sets of blood cultures from separate sites (first and last at least 1 hour apart) and perform echocardiography expeditiously 9.