The impact of the 2007 American Heart Association endocarditis prophylaxis guidelines on clinician practice has not been well established. Our objective was to evaluate how the American Heart Association endocarditis guidelines changed the practice of cardiologists who manage congenital heart disease and to ascertain the degree of practice variation among cardiologists.

A cross-sectional Web-based survey was e-mailed to Canadian (n = 134), Australian (n = 33), New Zealand (n = 9), and a random sample of American (n = 250) pediatric and adult congenital heart disease cardiologists in 2008. Nonrespondents received the survey 4 times by e-mail and once by regular post.

The response rate was 55%. The lesions for which cardiologists were most evenly divided between recommending versus not recommending prophylaxis were “rheumatic mitral stenosis of moderate severity” (45% recommended prophylaxis) and “perimembranous ventricular septal defect (VSD) status post surgical patch closure with no residual shunt 3 months post-operatively” (54% recommended prophylaxis). The lesions for which the greatest proportion of cardiologists discontinued prophylaxis were “small muscular VSD, no previous endocarditis” (80% discontinued prophylaxis) and “small audible patent ductus arteriosus” (83% discontinued prophylaxis). Only 69% recommended prophylaxis for “VSD s/p surgical patch closure with small residual shunt” despite current guidelines recommending prophylaxis for this scenario. Twenty-eight percent of respondents felt that the new guidelines leave some patients at risk, and 6% would not recounsel any low-risk patients following these guidelines.

The 2007 guidelines have resulted in a substantial change in endocarditis prophylaxis. There remains considerable heterogeneity among cardiologists regarding the prophylaxis of certain cardiac lesions.