Endocarditis prophylaxis: the new guidelines

1 Endocarditis prophylaxis : the new guidelines roperly controlled clinical antibiotic trials for P. NEW AHA REGIMENS. the prevention of bacterial Endocarditis in humans have never been done. Recommen- The new prophylactic regimen for dental, oral, or dations for antibiotic chemoprophylaxis are upper respiratory tract procedures in patients at risk for based on in vitro studies, vast clinical experience, data Streptococcus viridans bacteremia is the following: (1). from experimental animal models, and consideration amoxicillin, 3 g orally 1 hour prior to the procedure, of those bacteria most likely to produce bacteremia followed by g 6 hours later; and (2) for penicillin-al- from a given site and those most likely to result in lergic patients, erythromycin ethylsuccinate, 800 mg; or Endocarditis .

2 The American Heart Association erythromycin stearate, 1 g orally 2 hours prior to the (AHA) first issued prevention guidelines in 1965, with procedure, followed by half-dosage 6 hours later; or periodic revisions since then, most recently in the clindamycin, 300 mg orally 1 hour before the procedure December 12, 1990 issue of the Journal of the American and 150 mg 6 hours after the procedure. The major Medical This latest revision reflects a con- change from the previous AHA guidelines (1984) is the tinuing evolution based on accumulated clinical data selection of amoxicillin as the beta-lactam antibiotic of and animal experiments.

3 Major changes include choice, as it displays better absorption than either am- shorter periods of antibiotic coverage and use of oral picillin or penicillin V. The formulation of antibiotic prophylaxis when possible. It must be stated erythromycin now recommended is either the stearate emphatically that these are only guidelines and are not or ethylsuccinate preparation, again because of better intended as a standard of care in all cases. Practitioners absorption and higher predicted serum concentrations. must exercise their own clinical judgment in in- For patients unable to take oral medications, the dividual cases or special circumstances, and endocar- recommendations are as follows: (1) ampicillin, 2 g ditis may occur despite appropriate antibiotic intravenously (IV) or intramuscularly (IM), 30.

4 prophylaxis . Scientific organizations in other countries minutes before the procedure, followed by ampicillin 1. have also formulated recommendations which may g IV or IM, or amoxicillin, g orally 6 hours after the vary in certain respects from the AHA procedure; and (2) for penicillin-allergic patients, clin- Surgical and dental procedures and instrumenta- damycin, 300 mg IV 30 minutes before the procedure, tion involving mucosal surfaces or contaminated tis- and 150 mg IV or orally 6 hours later. sue commonly cause transient bacteremia of short For high-risk patients (ie, those with prosthetic duration.)

5 Blood-borne bacteria may lodge on damaged heart valves, prior Endocarditis , surgically constructed or abnormal heart valves or on the endocardium or systemic-pulmonary shunts or conduits) who are not the endothelium near congenital defects, resulting in candidates for the standard regimen, the recommenda- bacterial Endocarditis or endarteritis. Only a small tions are: (1) ampicillin, 2 g IV or IM plus gentamicin, number of bacterial species commonly cause endocar- mg/kg IV or IM 30 minutes before the procedure, ditis, and certain cardiac conditions are more often followed by amoxicillin, g orally 6 hours later; and associated with Endocarditis than others (Table 1).

6 (2) for penicillin-allergic patients, vancomycin, 1 g IV. Furthermore, certain dental and surgical procedures over 1 hour as a single dose, beginning 1 hour before are much more likely to initiate the bacteremia that the procedure; no repeated dose is necessary. results in Endocarditis than are other procedures When the entry site is either the genitourinary or the (Table 2). gastrointestinal tract, enterococcus is the most likely 114 CLEVELAND CLINIC JOURNAL OF MEDICINE VOLUME 59 NUMBER 2. Downloaded from on September 1, 2022. For personal use only. All other uses require permission.

7 Endocarditis LERNER. pathogen. For prevention of bacterial Endocarditis in TABLE 1. patients undergoing genitourinary or gastrointestinal Endocarditis prophylaxis IN CARDIAC CONDITIONS. procedures or both, the following schedule is still prophylaxis recommended recommended: (1) ampicillin, 2 g IV or IM, plus gen- Prosthetic cardiac valves (bioprosthetic or homograft). tamicin, mg/kg (not to exceed 80 mg) IV 30 Prior bacterial Endocarditis Most congenital cardiac malformations minutes before the procedure, followed by amoxicillin, Acquired valvular dysfunction (eg, rheumatic, surgical).

8 G 6 hours later; and (2) for penicillin-allergic in- Hypertrophic cardiomyopathy Mitral valve prolapse with valvular regurgitation dividuals, vancomycin, 1 g IV over 1 hour, plus gen- prophylaxis not recommended tamicin, mg/kg IV or IM 1 hour before the proce- Isolated secundum atrial septal defect dure, with an option to repeat the dose 8 hours after the Surgical repair (without residual) beyond 6 months for secundum atrial initial dose. Also included is an oral regimen for low- septal defect, ventricular septal defect, and patent ductus arteriosus Previous coronary artery bypass graft surgery risk patients using amoxicillin as outlined above for Mitral valve prolapse without valvular regurgitation*.

9 Dental procedures. Physiologic, functional, or innocent heart murmurs Prior Kawasaki disease without valve dysfunction Prior rheumatic fever without valve dysfunction PATIENT SELECTION Cardiac pacemakers and implanted defibrillators *Mitral valve prolapse associated with thickening or redundancy of valve leaflets Which patients should receive prophylaxis ? Head- may be at increased risk for bacterial Endocarditis , especially in men age 45 and older. ing the list (Table I) are patients with prosthetic car- diac valves, including not only artificial valves, but bioprosthetic valves as well, both the heterograft and homograft varieties.

10 By definition, any patient with a tions or vigorous cleaning if it includes scaling below history of bacterial Endocarditis , with or without the gingival margin (Table 2). The risk of bleeding preexisting heart disease, has at least one or more during these kinds of procedures is clearly determined damaged valves and is therefore a candidate for future by the extent of gingival inflammation. Also recom- prophylaxis . Patients with rheumatic or other acquired mended for prophylaxis are tonsillectomy, adenoidec- valvular dysfunctions and those with most congenital tomy, surgical procedures involving transection of the cardiac malformations require prophylaxis .