Non-infectious endocarditis: causes, symptoms, diagnosis, treatment

Non-infective endocarditis (non-bacterial thromboendocarditis) is a disease accompanied by the formation of a sterile platelet and fibrin thrombus on the heart valves and adjacent endocardium in response to trauma, circulating immune complexes, vasculitis, or increased blood clotting. Symptoms of non-infective endocarditis include manifestations of systemic arterial embolism. Diagnosis is based on echocardiography and negative bacteriological blood tests. Treatment consists of anticoagulants.

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What causes noninfective endocarditis?

Vegetations are caused by physical trauma rather than infection. They may be asymptomatic or may predispose to infective endocarditis, embolism, or cause valvular dysfunction.

Insertion of catheters through the right side of the heart may damage the tricuspid or pulmonary valve, resulting in platelet and fibrin adhesion at the site of injury. In diseases such as SLE, circulating immune complexes may cause loose platelet and fibrin vegetations to develop along the appositional areas of the valve leaflets (Liebman-Sachs endocarditis).

Procedures requiring antimicrobial prophylaxis endocarditis

Dental procedures manipulations in the oral cavity

Medical surgical procedures

Tooth extraction. Installation of fillings or crowns, treatment of already filled teeth. Local injections of anesthetic. Periodontal procedures including surgical treatment, extraction, root canal treatment and diagnostic canal probing. Preventive cleaning of teeth or implants if there is a risk of bleeding. Instrumental treatment of the root canal of the tooth or surgical treatment beyond the apex of the tooth. Subgingival placement of orthodontic appliances, but not braces

Surgical operations on the biliary tract. Rigid bronchoscopy. Cystoscopy. ERCP for biliary obstruction. Dilation of esophageal strictures. Surgical intervention on the intestinal mucosa. Prostate surgery. Operations on the mucous membrane of the respiratory tract. Sclerotherapy for esophageal varices. Tonsillectomy or adenoidectomy. Urethral dilation

Recommended prophylaxis of endocarditis during oral dental, respiratory, or endoscopic procedures

Route of administration of the drug	The drug for adults and children	A drug for people with allergies to penicillins
Orally (1 hour before the procedure)	Amoxicillin 2 g (50 mg/kg)	Clindamycin 600 mg (20 mg/kg). Cephalexin or cefadroxil 2 g (50 mg/kg). Azithromycin or clarithromycin 500 mg (15 mg/kg)
Parenteral (30 minutes before the procedure)	Ampicillin 2 g (50 mg/kg) IM or IV	Clindamycin 600 mg (20 mg/kg) i.v. Cefazolin 1 g (25 mg/kg) i.m. or i.v.

* Patients at moderate and high risk.

Recommended endocarditis prophylaxis during invasive gastrointestinal or urinary tract procedures

Risk level*	Drug and dosage	A drug for people with allergies to penicillins
High	Ampicillin 2 g IM or IV (50 mg/kg) and gentamicin 1.5 mg/kg (1.5 mg/kg) - do not exceed a dose of 120 mg - IV or IM 30 minutes before the procedure; ampicillin 1 g (25 mg/kg) IM or IV or amoxicillin 1 g (25 mg/kg) orally 6 hours after the procedure	Vancomycin 1 g (20 mg/kg) IV at least 1-2 hours before and gentamicin 1.5 mg/kg (1.5 mg/kg) - do not exceed a dose of 120 mg - IV or IM 30 minutes before the procedure
Moderate	Amoxicillin 2 g (50 mg/kg) orally 1 hour before the procedure or ampicillin 2 g (50 mg/kg) intramuscularly or intravenously 1-2 hours before the start of the procedure	Vancomycin 1 g (20 mg/kg) for 1-2 hours, finish 30 minutes before the procedure

* Risk assessment is based on accompanying conditions:

High risk - artificial heart valve (bioprosthetic or allograft), history of endocarditis, cyanotic congenital heart defects, surgically reconstructed systemic pulmonary shunts or anastomoses;

Moderate risk - congenital heart defects, acquired valvular insufficiency, hypertrophic cardiomyopathy, mitral valve prolapse with noise or thickened valve leaflets.

These lesions usually do not cause significant valvular obstruction or regurgitation. Antiphospholipid syndrome (lupus anticoagulant, recurrent venous thromboses, stroke, spontaneous abortions, livedo reticularis aestivalis) can also lead to sterile endocardial vegetations and systemic embolism. Occasionally, Wegener's granulomatosis leads to noninfective endocarditis.

Marantic endocarditis. In patients with chronic wasting diseases, disseminated intravascular coagulation, mucin-producing metastatic cancer (lung, stomach, or pancreas), or chronic infections (such as tuberculosis, pneumonia, osteomyelitis), large thrombotic vegetations may form on the valves and cause widespread emboli to the brain, kidneys, spleen, mesentery, extremities, and coronary arteries. These vegetations tend to form on congenitally malformed heart valves or valves damaged by rheumatic fever.

Symptoms of non-infective endocarditis

The vegetations themselves do not cause clinical manifestations. Symptoms are a consequence of embolism and depend on the affected organ (brain, kidney, spleen). Sometimes fever and heart murmur are detected.

Noninfective endocarditis should be suspected when a chronic patient develops symptoms suggestive of arterial embolism. Serial blood cultures and echocardiography are performed. Negative cultures and the identification of valvular vegetations (but not atrial myxoma) support the diagnosis. Examination of embolic fragments after embolectomy also helps in making the diagnosis. Differential diagnosis with infective endocarditis associated with negative blood cultures is often difficult but is important because anticoagulants prescribed for noninfective endocarditis are contraindicated in endocarditis of infectious etiology.

Prognosis and treatment of non-infective endocarditis

The prognosis is generally poor, more because of the severity of the underlying pathology than because of cardiac involvement. Treatment includes anticoagulant therapy with sodium heparin or warfarin, although there have been no studies evaluating the results of such treatment. Treatment of the underlying disease is indicated, if possible.