Infective Endocarditis Prophylaxis

Abstract & Commentary

Synopsis: Of the patients who underwent a procedure where IE prophylaxis was indicated, 13.2% did not follow their physician’s advice to take IE prophylaxis.

Source: Seto TB, et al. JAMA 2000;284:68-71.

Physicians often perform procedures of the genitourinary tract in which antibiotic prophylaxis may be indicated for patients with certain cardiac conditions. But is infective endocarditis (IE) prophylaxis being used appropriately?

Seto and colleagues surveyed a group of 108 patients with cardiac diagnoses derived from transesophageal echocardiograms performed at a university-based cardiology laboratory during a month-long period. These patients were initially classified for IE risk using the American Heart Association 1997 guidelines as high, moderate, and negligible risk. Of eligible patients, 80% completed a survey within 6-9 months following their echocardiograms.

Of the patients studied, 49.5% were candidates for IE prophylaxis based on high or moderate risk diagnoses. Approximately 45.9% of all patients reported physician recommendation for IE prophylaxis. Most (88.9%) of the high-risk patients received physician instruction to take IE prophylaxis, but only 61.1% of moderate-risk patients were instructed to take IE prophylaxis. Additionally, 26.4% of negligible risk patients were instructed to take IE prophylaxis. Of those who underwent a procedure where IE prophylaxis was indicated, 13.2% did not follow their physician’s advice to take IE prophylaxis.

Comment by Ellen L. Sakornbut, MD

The 1997 American Heart Association guidelines classify cardiac lesions in the following manner:

1. High-risk patients include all patients with a previous diagnosis of infective endocarditis, all patients with prosthetic heart valves, cyanotic congenital heart disease, and patients with surgical pulmonary shunt procedures.

2. Moderate-risk patients include other congenital malformations (except isolated secundum atrial septal defect), mitral valve prolapse with regurgitation or thickened mitral valve leaflets, acquired valvular disease, and hypertrophic cardiomyopathy.

3. Negligible-risk patients include patients with mitral valve prolapse without regurgitation, isolated secundum atrial septal defect, pacemaker or defibrillator implantation, and functional heart murmurs.

Additional patients needing IE prophylaxis include those with acquired valvular heart disease secondary to appetite-suppressant drugs, classified by the FDA as valvular stenosis, at least mild aortic regurgitation, thickened mitral leaflets with at least mild regurgitation, or moderate mitral or tricuspid regurgitation. In addition, although dental procedures and surgical procedures are commonly remembered as a possible risk to patients with valvular heart disease, any significant focal infection may create a risk for IE in patients in the moderate-to high-risk group.

The report by Seto et al is disturbing both in the failure of physicians to uniformly recommend IE prophylaxis to high- and moderate-risk patients and the failure of patients to follow their physicians’ recommendations. Some may consider it less concerning that IE prophylaxis was recommended for patients with negligible risk. Nonetheless, the use of antibiotics without clear medical indication should be considered as an issue not only of cost, but also of possible contribution to the development of antibiotic resistance. Patient education, identification, and implementation of treatment protocols should be conducted in a manner most likely to uniformly accomplish IE prophylaxis as indicated, perhaps incorporating antibiotic regimens in standard order sheets and screening questions in prenatal forms. (Dr. Sakornbut is Associate Professor, University of Tennessee-Memphis.)