Native cardiac disease predisposing to infective endocarditis.

Although no epidemiological studies are available to evaluate the exact risk of infective endocarditis complicating native cardiac disease, analysis of data in the literature shows that cardiac disease can be classified into three groups of decreasing risk: (1) high risk disease includes cyanotic congenital heart lesions, previous bacterial endocarditis, aortic valve disease, mitral regurgitation and uncorrected left-to-right shunt, but not atrial septal defect; (2) cardiac conditions of moderate risk include mitral valve prolapse with valvar regurgitation or leaflet thickening, isolated mitral stenosis, tricuspid valve disease, pulmonary stenosis and hypertrophic cardiomyopathy; (3) conditions of low or no risk include isolated atrial septal defect, ischaemic heart disease and/or previous coronary artery bypass graft surgery, surgically corrected left-to-right shunt with no residual shunt, mitral valve prolapse with thin leaflets in the absence of regurgitation, and calcification of the mitral annulus.