Time-related distribution, risk factors and prognostic influence of embolism in patients with left-sided infective endocarditis

BACKGROUND: Few studies evaluated systemic arterial embolism after beginning of symptoms of infective endocarditis in a large series of patients. METHODS: We studied 629 patients with left-sided infective endocarditis, aged 37.9+/-17.3 years, 396(63%) men and 233(37%) women. Endocarditis occurred on native valves in 405(64.4%) patients and on prosthetic heart valves in 224(35.6%). Infecting microorganisms were streptococci in 297(47.3%) patients, Staphylococcus aureus in 77(12.3%), Staphylococcus epidermidis in 56(8.9%), enterococci in 51(8.1%), Gram-negative bacteria in 33(5.2%), fungi in 9(1.4%) and other microorganisms in 27(4.2%). In 79(12.6%) patients blood cultures were negative. RESULTS: 146 embolic events occurred in 133(21.1%) out of 629 patients; in 63(47.4%) of them emboli affected the central nervous system, in 57(42.9%) affected peripheral organs and in 13(9.7%) affected both the central nervous system and peripheral organs. Embolism occurred between beginning of symptoms of endocarditis and antimicrobial therapy in 56(42.1%) patients and on the day therapy started in 18(13.5%); 109(81.9%) embolic events occurred up to the 15th day of antimicrobial therapy. Embolic risk was higher in S. aureus endocarditis (relative risk 2.97); in patients with a mitral (relative risk 2.4) or aortic (relative risk 3.3) prosthetic valve and vegetations on echocardiography. Embolic risk was lower in patients with a longer duration of symptoms. The death risk doubled in patients with embolism (relative risk 2.01). CONCLUSIONS: Embolic events were more frequently early events after beginning of symptoms of infective endocarditis. Embolic risk was higher in S. aureus endocarditis and in patients with prosthetic heart valves and vegetations on echocardiography.