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Subject: Re: Prevention of Endocarditis
Forum: The Heart Forum
Topic Area: Mitral Valve
Posted by Melissa on July 27, 1999 at 09:57:19I have been diagnosed with a myxomatous degeneration of the posterior leaflet of my prolapsed mitral valve. Please tell me how progresive this is. Also, my doctor has told me to take 2 Gr. of antibiotics (amoxicillin) one hour before dental cleaning and 2 Gr. 6 hours afterwards. I have heard that the dosage of 2 Gr. 6 hours afterwards has been eliminated. Is this true? I don't want to take additional antibiotics if I don't need them. Thanks so much for making this forum possible. It has helped so many of us.
Melissa
Posted by CCF CARDIO MD - CRC on July 27, 1999 at 10:58:45The degeneration of the valve depends on the mechanism, the degree of damage already present and other factors we dont fully understand. It may never need correction but on the other hand may someday require surgery. You are correct that the post-procedure dose is no longer recommended by the AHA. Your doctor however is the one who should make the final decision about what is right for you. Here is a full copy of the report.
Copyright 1997 by the American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply
to Government Use. American Medical Association, 515 N. State St, Chicago, IL 60610.
Volume 277(22) 11 June 1997 pp 1794-1801 Prevention of Bacterial Endocarditis: Recommendations by the American Heart Association
[Clinical Cardiology] Dajani, Adnan S. MD; Taubert, Kathryn A. PhD; Wilson, Walter MD; Bolger, Ann F. MD; Bayer, Arnold MD; Ferrieri,
Patricia MD; Gewitz, Michael H. MD; Shulman, Stanford T. MD; Nouri, Soraya MD; Newburger, Jane W. MD; Hutto,
Cecilia MD; Pallasch, Thomas J. DDS, MS; Gage, Tommy W. DDS, PhD; Levison, Matthew E. MD; Peter, Georges MD;
Zuccaro, Gregory Jr, MD From the American Heart Association, Dallas, Tex (Drs Dajani, Taubert, Wilson, Bolger, Bayer, Ferrieri, Gewitz, Shulman, Nouri, Newburger, and
Hutto); American Dental Association, Chicago, Ill (Drs Pallasch and Gage); the Infectious Diseases Society of America, Alexandria, Va (Dr
Levison); American Academy of Pediatrics, Elk Grove Village, Ill (Dr Peter); and American Society for Gastrointestinal Endoscopy, Manchester,
Mass (Dr Zuccaro). Abstract Objective: To update recommendations issued by the American Heart Association last published in 1990 for the prevention of bacterial
endocarditis in individuals at risk for this disease. Participants: An ad hoc writing group appointed by the American Heart Association for their expertise in endocarditis and treatment with
liaison members representing the American Dental Association, the Infectious Diseases Society of America, the American Academy of
Pediatrics, and the American Society for Gastrointestinal Endoscopy. Evidence.The recommendations in this article reflect analyses of relevant literature regarding procedure-related endocarditis, in vitro
susceptibility data of pathogens causing endocarditis, results of prophylactic studies in animal models of endocarditis, and retrospective
analyses of human endocarditis cases in terms of antibiotic prophylaxis usage patterns and apparent prophylaxis failures. MEDLINE database
searches from 1936 through 1996 were done using the root words endocarditis, bacteremia, and antibiotic prophylaxis. Recommendations in this
document fall into evidence level III of the US Preventive Services Task Force categories of evidence. Consensus Process.The recommendations were formulated by the writing group after specific therapeutic regimens were discussed. The
consensus statement was subsequently reviewed by outside experts not affiliated with the writing group and by the Science Advisory and
Coordinating Committee of the American Heart Association. These guidelines are meant to aid practitioners but are not intended as the
standard of care or as a substitute for clinical judgment. Conclusions: Major changes in the updated recommendations include the following: (1) emphasis that most cases of endocarditis are not
attributable to an invasive procedure; (2) cardiac conditions are stratified into high-, moderate-, and negligible-risk categories based on
potential outcome if endocarditis develops; (3) procedures that may cause bacteremia and for which prophylaxis is recommended are more
clearly specified; (4) an algorithm was developed to more clearly define when prophylaxis is recommended for patients with mitral valve
prolapse; (5) for oral or dental procedures the initial amoxicillin dose is reduced to 2 g, a follow-up antibiotic dose is no longer recommended,
erythromycin is no longer recommended for penicillin-allergic individuals, but clindamycin and other alternatives are offered; and (6) for
gastrointestinal or genitourinary procedures, the prophylactic regimens have been simplified. These changes were instituted to more clearly
define when prophylaxis is or is not recommended, improve practitioner and patient compliance, reduce cost and potential gastrointestinal
adverse effects, and approach more uniform worldwide recommendations. JAMA.1997;277:1794-1801 Clinical Cardiology section editors: Bruce Brundage, MD, University of California, Los Angeles, School of Medicine; Margaret
A. Winker, MD, Senior Editor, JAMA. ENDOCARDITIS is a life-threatening disease, although it is relatively uncommon. Substantial morbidity and mortality result
from this infection, despite improvements in outcome due to advances in antimicrobial therapy and enhanced ability to diagnose
and treat complications. Primary prevention of endocarditis whenever possible is therefore very important. Endocarditis usually develops in individuals with underlying structural cardiac defects who develop bacteremia with organisms
likely to cause endocarditis. Bacteremia may occur spontaneously or may complicate a focal infection (eg, urinary tract
infection, pneumonia, or cellulitis). Some surgical and dental procedures and instrumentations involving mucosal surfaces or
contaminated tissue cause transient bacteremia that rarely persists for more than 15 minutes. Blood-borne bacteria may lodge
on damaged or abnormal heart valves or on the endocardium or the endothelium near anatomic defects, resulting in bacterial
endocarditis or endarteritis. Although bacteremia is common following many invasive procedures, only certain bacteria
commonly cause endocarditis. It is not always possible to predict which patients will develop this infection or which particular
procedure will be responsible. There are currently no randomized and carefully controlled human trials in patients with underlying structural heart disease to
definitively establish that antibiotic prophylaxis provides protection against development of endocarditis during
bacteremia-inducing procedures. Further, most cases of endocarditisare not attributable to an invasive procedure. The
following recommendations reflect analyses of relevant literature regarding procedure-related endocarditis, including in vitro
susceptibility data of pathogens causing endocarditis, results of prophylactic studies in experimental animal models of
endocarditis, and retrospective analyses of human endocarditis cases in terms of antibiotic prophylaxis usage patterns and
apparent prophylaxis failures. The incidence of endocarditis following most procedures in patients with underlying cardiac disease is low. A reasonable
approach for endocarditis prophylaxis should consider the following: the degree to which the patient's underlying condition
creates a risk of endocarditis; the apparent risk of bacteremia with the procedure (as defined in these recommendations); the
potential adverse reactions of the prophylactic antimicrobial agent to be used; and the cost-benefit aspects of the recommended
prophylactic regimen. Failure to consider all of these factors may lead to overuse of antimicrobial agents, excessive cost, and
risk of adverse drug reactions. This statement provides guidelines for prevention of bacterial endocarditis. It is not intended as the standard of care or as a
substitute for clinical judgment. The current recommendations are an update of those made by the committee in 1990 [1] and
incorporate new data and include opinions voiced by national and international experts at endocarditis meetings around the
world. CARDIAC CONDITIONS
Certain cardiac conditions are associated with endocarditis more often than others. [2] Furthermore, when endocarditis
develops in individuals with underlying cardiac conditions, the severity of the disease and the ensuing morbidity can be variable.
Prophylaxis is recommended in individuals who have a higher risk for developing endocarditis than the general population and is
particularly important for individuals in whom endocardial infection is associated with high morbidity and mortality. ( Table 1) [2-22] stratifies cardiac conditions into high- and moderate-risk categories primarily on the basis of potential
outcome if endocarditis occurs. High Risk
Individuals at highest risk are those who have prosthetic heart valves, a previous history of endocarditis (even in the absence of
other heart disease), complex cyanotic congenital heart disease, or surgically constructed systemic pulmonary shunts or
conduits. [2,3] These individuals are at a much higher risk for developing severe endocardial infection that is often associated
with high morbidity and mortality. Moderate Risk
Individuals with certain other underlying cardiac defects are at moderate risk for severe infection. [2-4] Congenital cardiac
conditions listed in the moderate-risk category include the following uncorrected conditions: patent ductus arteriosus, ventricular
septal defect, primum atrial septal defect, coarctation of the aorta, and bicuspid aortic valve. Acquired valvar dysfunction (eg,
due to rheumatic heart disease or collagen vascular disease) and hypertrophic cardiomyopathy are also moderate-risk
conditions. Mitral valve prolapse (MVP) is common, and the need for prophylaxis for this condition is controversial. Only a small
percentage of patients with documented MVP develop complications at any age. [5-7] Mitral valve prolapse represents a
spectrum of valvular changes and clinical behavior. [5-7] In view of the controversy surrounding the need for prophylaxis of the
individual patient with MVP, a detailed description of the spectrum of MVP is warranted. Normal mitral valve leaflets close at or below the plane of the mitral annulus. This closure position is controlled by the lengths of
the leaflets, their attached chordae and papillary muscles, and the systolic size of the ventricle. The closure position will shift
beyond the annular plane toward the left atrium, or prolapse, if the lengths of the valve apparatus, which are constant, become
too large for the size of the end-systolic ventricle, which is variable and dynamic. Dehydration and tachycardia are common
causes of intermittent MVP. Abnormal motion of normal mitral valves is found on echocardiographic examination in a small
percentage of the adult and adolescent ambulatory population. The high prevalence of such motion abnormalities in young
adults underscores that MVP is often an abnormality of volume status, adrenergic state, or growth phase and not of valve
structure or function. When normal valves prolapse without leaking, as in patients with 1 or more systolic clicks but no murmurs
and no Doppler-demonstrated mitral regurgitation, the risk of endocarditis is not increased above that of the normal population.
[2,6,7] Antibiotic prophylaxis against bacterial endocarditis is therefore not necessary. This is because it is not the abnormal
valve motion but the jet of mitral insufficiency that creates the shear forces and flow abnormalities that increase the likelihood of
bacterial adherence on the valve during bacteremia. Normal mitral valves with normal motion often have minimal leaks detectable by Doppler examination. This does not appear to
increase the risk of endocarditis. In contrast, the regurgitation that occurs with structurally normal but prolapsing valves
originates from larger regurgitant orifices and creates broader areas of turbulent flow. Patients with prolapsing and leaking mitral
valves, evidenced by audible clicks and murmurs of mitral regurgitation or by Doppler-demonstrated mitral insufficiency, should
receive prophylactic antibiotics. [7-11] This is supported by formal cost-benefit analysis. [12] Mitral valve prolapse also occurs in the setting of myxomatous degeneration of the mitral valve. This is a progressive disorder
that has a spectrum of manifestations. [13,14] The mitral leaflets of these patients appear thickened on the echocardiogram, due
to accumulations of proteoglycan deposits. [15] The amount of thickening is variable and may increase with age. [16] There is a
range of valve motion in these patients as well: they may prolapse continuously or only with changes in heart rate or volume.
Further, when prolapse occurs, it may or may not create valvular insufficiency. In patients of any age, myxomatous mitral valve
degeneration with regurgitation is an indication for antibiotic prophylaxis. [11,17,18] Anterior mitral valve thickening is commonly found in both competent and insufficient myxomatous mitral valves, but its
presence increases the likelihood of significant mitral regurgitation. [16] Those with significant regurgitation were older and more
likely to be men. [16] Other studies have shown that male sex and age older than 45 years represent increased risk for
developing endocarditis. [8,10,11,19] Patients with thickened valves that do not leak on resting examination often develop
regurgitation with exercise. These patients with exercise-induced mitral insufficiency have been shown to constitute a higher-risk
subset for common complications (syncope, congestive heart failure, progressive regurgitation requiring valve replacement);
endocarditis and cerebral embolic events, occurring far less frequently, were not demonstrated to be increased in this small
series. [20] Men older than 45 years with MVP, without a consistent systolic murmur, may warrant prophylaxis even in the
absence of resting regurgitation. [12,19] Some experts feel that an audible nonejection click even without a murmur may identify patients with a potential for intermittent
regurgitation and therefore a risk of developing endocarditis. While there are insufficient data on this issue, an isolated click may
be an indication for more thorough evaluation of valve morphology and function, including Doppler-echocardiographic imaging
or auscultation during maneuvers that elicit or augment mitral regurgitation. While children and adolescents with MVP may have the same symptoms as adults, such as palpitations or syncope, the
development of symptoms in childhood is relatively unusual. The vast majority of children with chest pain or fatigue do not have
any form of heart disease, including MVP. Careful evaluation is nevertheless required in children who have isolated clinical
findings, such as nonejection systolic click, since this may be the only indicator of important mitral valve abnormality requiring
prophylaxis. [21] In the most recent series of reports, MVP has emerged as an important underlying diagnosis associated with
endocarditis in the pediatric age group. [3,21] A clinical approach to determination of the need for prophylaxis in individuals with suspected MVP is given in ( Figure 1). [23]
egligible Risk
Although endocarditis may develop in any individual, including persons with no underlying cardiac defect, the negligible-risk
category lists cardiac conditions in which the development of endocarditis is not higher than in the general population. Whereas
in pediatric patients innocent heart murmurs may be clearly defined on auscultation, in the adult population other studies such as
echocardiography may be necessary to confirm that a murmur is innocent. Individuals with innocent heart murmurs have
structurally normal hearts and do not require prophylaxis. BACTEREMIA-PRODUCING PROCEDURES
Bacteremias commonly occur during activities of daily living such as routine tooth brushing or chewing. With respect to
endocarditis prophylaxis, significant bacteremias are only those caused by organisms commonly associated with endocarditis
and attributable to identifiable procedures. The procedures for which prophylaxis is recommended are those known to induce
such bacteremias and are discussed below. Invasive procedures performed through surgically scrubbed skin are not likely to
produce such bacteremias. Many centers do employ periprocedure prophylaxis for transcatheter insertion of prosthetic devices
(septal occluders and vascular coils), however, although there are no data to support the use of antibiotics in the procedures.
Routine cardiac catheterization and angioplasty do not require such precautions. DENTAL AND ORAL PROCEDURES
Poor dental hygiene and periodontal or periapical infections may produce bacteremia even in the absence of dental procedures.
The incidence and magnitude of bacteremias of oral origin are directly proportional to the degree of oral inflammation and
infection. [24,25] Individuals who are at risk for developing bacterial endocarditis should establish and maintain the best
possible oral health to reduce potential sources of bacterial seeding. Optimal oral health is maintained through regular
professional care [24,26,27] and the use of appropriate dental products such as manual and powered toothbrushes, dental
floss, and other plaque-removal devices. Oral irrigator or air abrasive polishing devices used inappropriately or in patients with
poor oral hygiene have been implicated in producing bacteremia, but the relationship to bacterial endocarditis is unknown.
[24,28-31] Home-use devices pose far less risk of bacteremia in a healthy mouth than does ongoing oral inflammation.
[24,28-31] Antiseptic mouth rinses applied immediately prior to dental procedures may reduce the incidence or magnitude of bacteremia.
[24] Agents include chlorhexidine hydrochloride and povidone-iodine. Fifteen milliliters of chlorhexidine can be given to all
at-risk patients via gentle oral rinsing for about 30 seconds prior to dental treatment; gingival irrigation is not recommended.
Sustained or repeated frequent interval use is not indicated as this may result in the selection of resistant microorganisms. [24] Antibiotic prophylaxis for at-risk patients is recommended for dental and oral procedures likely to cause bacteremia (( Table 2)
[22,24-26,28-31]). In general, prophylaxis is recommended for procedures associated with significant bleeding from hard or
soft tissues, periodontal surgery, scaling, and professional teeth cleaning. Similarly, antimicrobial prophylaxis is recommended
for tonsillectomy or adenoidectomy. It is recognized that unanticipated bleeding may occur on some occasions. In such an
event, data from experimental animal models suggest that antimicrobial prophylaxis administered within 2 hours following the
procedure will provide effective prophylaxis. [32] Antibiotics administered more than 4 hours after the procedure probably
have no prophylactic benefit. Procedures for which antimicrobial prophylaxis is not recommended are also listed ( Table 2).
PROPHYLACTIC REGIMENS
Prophylaxis is most effective when given perioperatively in doses that are sufficient to assure adequate antibiotic concentrations
in the serum during and after the procedure. To reduce the likelihood of microbial resistance, it is important that prophylactic
antibiotics be used only during the perioperative period. They should be initiated shortly before a procedure and should not be
continued for an extended period (no more than 6 to 8 hours). In the case of delayed healing, or of a procedure that involves
infected tissue, it may be necessary to provide additional doses of antibiotics for treatment of the established infection. Practitioners must exercise their own clinical judgment in determining the choice of antibiotics and number of doses that are to
be administered in individual cases or special circumstances. Furthermore, because endocarditis may occur in spite of
appropriate antibiotic prophylaxis, physicians and dentists should maintain a high index of suspicion regarding any unusual
clinical events (such as unexplained fever, night chills, weakness, myalgia, arthralgia, lethargy, or malaise) following dental or
other surgical procedures in patients who are at risk for developing bacterial endocarditis. Regimens for Dental, Oral, Respiratory Tract, or Esophageal Procedures
Streptococcus viridans (alpha-hemolytic streptococci) is the most common cause of endocarditis following dental or oral
procedures, certain upper respiratory tract procedures, bronchoscopy with a rigid bronchoscope, surgical procedures that
involve the respiratory mucosa, and esophageal procedures. Prophylaxis should be specifically directed against these
organisms. The same regimens are recommended for all these procedures (( Table 4) [1,22,59-61]). The recommended
standard prophylactic regimen for all these procedures is a single dose of oral amoxicillin. The antibiotics amoxicillin, ampicillin,
and penicillin V are equally effective in vitro against alpha-hemolytic streptococci; however, amoxicillin is recommended
because it is better absorbed from the gastrointestinal tract and provides higher and more sustained serum levels. Previously the
recommended dose was 3.0 g 1 hour before a procedure and then 1.5 g 6 hours after the initial dose. [1] Recent comparisons
of 2.0-g and 3.0-g dosing indicate that a 2.0-g dose results in adequate serum levels for several hours and causes less
gastrointestinal adverse effects. [59] The newly recommended adult dose is 2.0 g of amoxicillin (pediatric dose is 50 mg/kg not
to exceed the adult dose) to be administered 1 hour before the anticipated procedure. A second dose is not necessary, both
because of the prolonged serum levels above the minimal inhibitory concentration of most oral streptococci [59] and the
prolonged serum inhibitory activity induced by amoxicillin against such strains (6-14 hours). [60] For individuals who are unable
to take or unable to absorb oral medications, a parenteral agent may be necessary. Ampicillin sodium is recommended because
parenteral amoxicillin is not available in the United States. Individuals who are allergic to penicillins (such as amoxicillin,
ampicillin, or penicillin) should be treated with the provided alternative oral regimens. Clindamycin hydrochloride is one
recommended alternative. Individuals who can tolerate first-generation cephalosporins (cephalexin or cefadroxil) may receive
these agents provided they have not had an immediate, local, or systemic IgE-mediated anaphylactic allergic reaction to
penicillin. Azithromycin or clarithromycin are also acceptable alternative agents for the penicillin-allergic individual, [61] although
they are more expensive than the other regimens. When parenteral administration is needed in an individual who is allergic to
penicillin, clindamycin phosphate is recommended; cefazolin may be used if the individual does not have an immediate type local
or systemic anaphylactic hypersensitivity to penicillin. The previous recommendations from this committee listed erythromycin as
an alternate agent for the penicillin-allergic patient. Erythromycin is no longer included because of gastrointestinal upset and
complicated pharmacokinetics of the various formulations. [62] Practitioners who have successfully used erythromycin for
prophylaxis in individual patients may choose to continue with this antibiotic. The regimen is included in our previous
recommendations. [1]
Edentulous patients may develop bacteremia from ulcers caused by ill-fitting dentures. Denture wearers should be encouraged
to have periodic examination or to return to the practitioner if discomfort develops. When new dentures are inserted, it is
advisable to have the patient return to the practitioner to correct any problems that could cause mucosal ulceration. If a series of dental procedures is required, it may be prudent to observe an interval of time between procedures to both reduce
the potential for the emergence of resistant organisms and allow repopulation of the mouth with antibiotic susceptible flora.
Various studies have suggested an interval of 9 [33] to 14 [34] days. If possible, a combination of procedures should be
planned within the same period of prophylaxis. I hope you find this information useful. Information provided in the heart forum is for general purposes only. Only your physician can provide specific diagnoses and therapies. Please feel free to write back with additional questions. If you would like to make an appointment at the Cleveland Clinic Heart Center, please call 1-800-CCF-CARE or inquire online by using the Heart Center website at www.ccf.org/heartcenter. The Heart Center website contains a directory of the cardiology staff that can be used to select the physician best suited to address your cardiac problem.
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