CORRESPONDENCE: LETTER TO THE EDITOR
In Defense of Antimicrobial Prophylaxis for Prevention of Infective Endocarditis in Patients With Hypertrophic Cardiomyopathy
Barry J. Maron, MD* and
Harry Lever, MD
* Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, 920 East 28th Street, Suite 620, Minneapolis, Minnesota 55407 (Email: hcm.maron{at}mhif.org).
We read with particular interest Bach's viewpoint editorial and critique (1) of the recent American Heart Association (AHA) revised recommendations for antimicrobial prevention of infective endocarditis (2). The "new" recommendations, which represent a striking change from the original guidelines followed for more than 50 years (1–5), are based largely on 2 risk versus benefit assumptions: 1) significant mortality or morbidity (e.g., anaphylaxis) associated with prophylactic antibiotic therapy; and 2) a lack of evidence (particularly, randomized trials) supporting the efficacy of antibiotic prophylaxis in the prevention of infective endocarditis.
Our concern regarding this debate is focused on hypertrophic cardiomyopathy (HCM) (6), a disease in which infective endocarditis is a well-documented and usually profound complication (6–9). Indeed, a survey of the PubMed archives identified 32 papers detailing the prevalence and the sometimes serious clinical consequences of endocarditis in HCM patients. While infective endocarditis is uncommon within the overall HCM population (8), when it does occur, its impact on valvular and cardiac function and risk for systemic emboli is usually consequential (7–9). Most reported cases have been associated with left ventricular outflow tract obstruction (vegetations most commonly appear on the thickened anterior mitral leaflet or adjacent surface of proximal ventricular septum), and we wish to underscore that fully 70% of HCM patients have the propensity to develop outflow obstruction at rest or with physiologic exercise (10).
We believe that the reversal of the "old" and familiar AHA guidelines on antimicrobial prophylaxis was an unfortunate mistake for patients with HCM, and indeed substantial confusion and uncertainty surrounding this issue has been created within the community of physicians, dentists, and patients with this disease. Notably, cardiovascular conditions that are relatively uncommon in clinical practice and with low event rates (such as HCM) are not amenable to the level of evidence sought by the AHA panel. However, just because it is not possible to assemble such evidence through randomized trials does not mean that a significant relationship between antibiotic treatment and prevention of infective endocarditis is nonexistent—nor does it mean that it is justified to simply negate the issue.
Perhaps this would be another matter if the potential benefit of prophylactic antibiotics were outweighed by the risks of treatment. However, as pointed out by Bach (1), and conceded in the AHA document (2), there has never been a documented anaphylactic death attributable to antibiotics administered prophylactically to prevent endocarditis. This is consistent with the authors' combined 60 years of experience with HCM, and countless patients who have taken antibiotics for that purpose.
It is obvious to us that following the most recent AHA recommendations and withholding antibiotics from patients with HCM will unavoidably have the effect of unnecessarily creating several new cases of infective endocarditis each year. We are at a loss to understand how these AHA recommendations (2), which we believe should be revised, are in the best interests of the HCM patient population.
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1. Bach DS. Perspectives on the American College of Cardiology/American Heart Association guidelines for the prevention of infective endocarditis J Am Coll Cardiol 2009;53:1852-1854.[Abstract/Free Full Text]2. Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis guidelines from the American Heart Association. A guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007;16:1736-1754. 3. Jones TD, Baumgartner L, Bellows MT, et al. Committee on Prevention of Rheumatic Fever and Bacterial Endocarditis, American Heart Association Prevention of rheumatic fever and bacterial endocarditis through control of streptococcal infections Circulation 1955;11:317-320.[Web of Science] 4. Dajani AS, Bisno AL, Chung KJ, et al. Prevention of bacterial endocarditis: recommendations by the American Heart Association JAMA 1990;264:2919-2922.[Abstract/Free Full Text] 5. Dajani AS, Taubert KA, Wilson W, et al. Prevention of bacterial endocarditis: recommendations by the American Heart Association JAMA 1997;277:1794-1801.[Abstract/Free Full Text] 6. Maron BJ, McKenna WJ, Danielson GK, et al. American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy: a report of the American College of Cardiology Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines Committee to Develop an Expert Consensus Document on Hypertrophic Cardiomyopathy J Am Coll Cardiol 2003;42:1687-1713.[Free Full Text] 7. Roberts WC, Kishel JC, McIntosh CL, Cannon III RO, Maron BJ. Severe mitral or aortic valve regurgitation, or both, requiring valve replacement for infective endocarditis complicating hypertrophic cardiomyopathy J Am Coll Cardiol 1992;19:365-371.[Abstract] 8. Spirito P, Rapezzi C, Bellone P, et al. Infective endocarditis in hypertrophic cardiomyopathy: prevalence, incidence, and indications for antibiotic prophylaxis Circulation 1999;99:2132-2137.[Abstract/Free Full Text] 9. Alessandri N, Pannarale G, del Monte F, Moretti F, Marino B, Reale A. Hypertrophic obstructive cardiomyopathy and infective endocarditis: a report of seven cases and a review of the literature Eur Heart J 1990;11:1041-1048.[Abstract/Free Full Text] 10. Maron MS, Olivotto I, Zenovich AG, et al. Hypertrophic cardiomyopathy is predominantly a disease of left ventricular outflow tract obstruction Circulation 2006;114:2232-2239.[Abstract/Free Full Text]
Related Article
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Reply
- David S. Bach
J. Am. Coll. Cardiol. 2009 54: 2340.
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