[Infectious endocarditis in non-addict patients without predisposing heart disease. Differential features]

Although uncommonly, infective endocarditis in non-addict patients may involve people without predisponente heart disease. The aim of our study was to assess the clinical and prognostic features of this type of endocarditis and to compare them with those of the more common type of endocarditis with underlying lesion.

With this aim, we have reviewed 71 consecutive cases of non-addict infective endocarditis diagnosed in our hospital in the last 7 years; there was no preexisting cardiac lesion in 9 patients (13% of all endocarditis and 21% of native valve endocarditis), while underlying heart disease, including mitral valve prolapse, was present in the remaining 62 patients.

Mean age was significantly lower in 9 patients without preexistent lesion (28 +/- 18 versus 46 +/- 17 years, p < 0.01), while there was no differences for gender. Infection involved the aortic valve in 56%, the tricuspid or pulmonary valve in 33% and the mitral valve in only 11% of the patients without underlying cardiopathy (for 44%, 4% and 49%, respectively, in patients with cardiopathy). Staphylococcus aureus caused 67% of cases in patients without cardiopathy and only 9% in those with cardiopathy. Surgery was required in a similar proportion by both groups of patients (55% and 56%), although mortality was more than twice higher in patients with prior cardiac lesions (25% versus 11%).

A significant proportion of non-addict infective endocarditis involves patients without predisponente heart disease. These cases have some differential features (younger age, aortic and right heart valves involvement, S. aureus as the main causative agent and lower mortality) in comparison to those of endocarditis in patients with underlying cardiopathy.