Etiology and Risk Factors of 339 Cases of Infective Endocarditis: Report from a 10-year National Prospective Survey in the Slovak Republic

Abstract

The authors studied the etiology, outcome and risk factors of 339 cases of infective endocarditis (IE) in Slovakia over the last 10 years. Aortic valve was infected in 59.9%, mitral in 38.1% and tricuspidal/pulmonary in 5.0% of cases. The majority of IE were caused by staphylococci (29.2%), 15.0% were due to viridans streptococci, 7.4% due to Enterococcus faecalis, 3.9% due to the HACEK group (Haemophilus spp., Actinobacillus spp., Corynebacterium spp., Eikenella spp., Kingella spp.) and 39.2% were culture negative.

The following risk factors were the most frequently identified: rheumatic fever in 24.2%, dental surgery in 13.3%, previous cardiosurgery in 7.1% and neoplasia in 7.1%. All patients were treated with antimicrobials and 42.5% of patients also with surgery (valvular prosthesis replacement): 61 (18.0%) died, and 278 (82.0%) survived at day 60 after the diagnosis of endocarditis was made. Univariate analysis did not show significant differences in most of the recorded risk factors between patients who died and those who survived: apart from staphylococcal etiology (44.3% vs. 26.6%, P <0.01), persistent bacteremia (with three or more positive blood cultures 24.6% vs. 9.7% P <0.002) which were significantly associated with higher attributable mortality, as was absence of surgery (55.7% vs. 6.1% P < 0.001), whereas antibiotic therapy in combination with surgery significantly predicted better outcome (P <0.001).

We compared risk factors, etiology, therapeutic strategies and outcome of IE in two periods: from 1991-1997 (180 cases) and from 1998-2001 (159 cases). Rheumatic fever was less commonly observed in second period (1998-2001) P <0.01 since its prevalence in Slovakia is rapidly decreasing. Dental surgery was less frequent as well (20.5% vs. 5.0% P <0.001). There was a significant shift in etiology within the second study period: negative-culture endocarditis (despite better bacteriological techniques) (P <0.001) was more frequently observed in the 1st period and represented 53.3% of all cases in 1998-2001 in comparison to 26.7% in 1991-1997. Enterococci (P <0.0002) were also more frequent in the 2nd period. Persistent bacteremia (3 or more positive blood cultures 20.5% vs. 3.1%, P <0.001 was less commonly observed within the 2nd period (1998-2001) in comparison to 1991-1997.

More patients in the second period (1998-2001) had complications of IE (P<0.001) than in the 1st period. However mortality was lower (22.2% vs. 13.2%, P <0.044) because of more surgical intervention in the 2nd period (52.8% vs. 33.3%, P <0.001).