A 38-year-old woman is brought to the emergency department due to an episode of syncope. The patient has felt weak and has not eaten well over the last 2 weeks. As a result, she believes she is "dehydrated." Temperature is 38.2 C (100.8 F), blood pressure is 112/58 mm Hg, and pulse is 49/min and regular. The oral mucosa is dry and dentition is poor. An early diastolic murmur is heard at the left sternal border at full expiration. The lungs are clear. The abdomen is soft and nontender. ECG reveals sinus rhythm with a 2:1 second-degree atrioventricular block. Laboratory results are as follows:
| Leukocytes | 13,000/mm3 |
| Hemoglobin | 10.8 g/dL |
| Platelets | 410,000/mm3 |
Which of the following is the most likely diagnosis in this patient?
Common complications of infective endocarditis | |
Local (cardiac) |
|
Distant (embolic) |
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This patient's subacute weakness, anorexia, low-grade fever, leukocytosis, and thrombophilia indicate likely infection. Although localizing symptoms are absent, her poor dentition (a risk factor for Streptococcus viridans bacteremia) and likely aortic regurgitation (early diastolic murmur) raise suspicion for aortic valve infective endocarditis (IE). This is reinforced by her cardiac conduction abnormality (likely the source of her syncope), which is often seen when aortic valve IE progresses to a perivalvular abscess.
Perivalvular abscess occurs in 30%-40% of patients with aortic valve IE and is most common in those with a bicuspid valve. It is generally suspected when patients with IE have persistent bacteremia or develop cardiac conduction abnormalities (eg, heart block) on ECG. Conduction abnormalities are common because the aortic valve ring between the right cusp and the noncoronary cusp overlies the intraventricular septum, which harbors the proximal ventricular conduction system.
Aortic regurgitation due to valve disease (as seen in this patient) usually causes an early diastolic murmur best heard along the left sternal border (third and fourth intercostal spaces). In contrast, aortic regurgitation due to aortic root disease is usually associated with an early diastolic murmur best heard along the right sternal border. Transesophageal echocardiography is likely the best next step in this case because it is more sensitive for perivalvular abscess compared to transthoracic echocardiography; surgery will likely be necessary.
(Choice A) Acute pericarditis is marked by chest pain (sharp and pleuritic, improvement when sitting and leaning forward), pericardial friction rub, and diffuse, concave, upward ST-segment elevations across the precordial and limb leads on ECG.
(Choice B) Although Lyme disease can cause atrioventricular block and/or myopericarditis weeks or months after initial infection, the valves are typically spared; therefore, the presence of an aortic regurgitation murmur makes Lyme disease less likely than IE with perivalvular abscess.
(Choice C) Mitral valve perforation can occur as a complication of mitral valve endocarditis. It generally presents as acute congestive heart failure, along with a systolic murmur of mitral regurgitation.
(Choice E) Tricuspid valve endocarditis usually presents with a holosystolic murmur of tricuspid regurgitation that becomes accentuated with inspiration, rather than an early diastolic murmur strongly suggestive of aortic regurgitation. In addition, cardiac conduction abnormalities are less common with tricuspid valve endocarditis.
Educational objective:
Aortic valve infective endocarditis causes perivalvular abscess in 30%-40% of cases. This complication should be suspected in patients with persistent bacteremia or cardiac conduction abnormalities (eg, heart block).