Clinical Features, Site of Involvement, Bacteriologic Findings, and Outcome of Infective Endocarditis in Intravenous Drug Users

BACKGROUND: Intravenous drug use is an increasingly common condition predisposing to infective endocarditis. Data on infective endocarditis in intravenous drug users are limited. OBJECTIVE: To determine the clinical features, bacteriologic findings, site of involvement, complications, and mortality associated with infective endocarditis in intravenous drug users. METHODS: Cohort study of intravenous drug users with native valve infective endocarditis. RESULTS: A total of 125 cases of infective endocarditis occurred in 114 patients (84 cases 67% in men and 41 cases 32% in women) with a mean (+/- SD) age of 37 +/- 7 years. The tricuspid valve was involved in 58 cases (46%), the mitral valve in 40 cases (32%), and the aortic valve in 24 cases (19%). The microorganisms identified included Staphylococcus in 82 cases (65.6%) and Streptococcus in 32 cases (25.6%). Twenty-three patients (18%) underwent surgery, and two (9%) of them died. One hundred two patients (82%) were treated medically, and nine (9%) of them died. Fifteen patients (63%) with aortic valve involvement vs 17 patients (17%) without aortic valve involvement underwent surgery or died without surgery (odds ratio, 8.24; 95% confidence interval, 3.1 to 21.8). Among the survivors, at least one major cardiovascular complication occurred in 79 cases (69.3%). CONCLUSIONS: Infective endocarditis in intravenous drug users affects the right and left sides of the heart with approximately equal frequency. At present, more than 90% of cases of infective endocarditis in intravenous drug users in Chicago are caused by staphylococci or streptococci. Involvement of the aortic valve is predictive of increased morbidity and mortality in intravenous drug users with infective endocarditis. With medical treatment, and surgery when medical treatment fails, intravenous drug users with infective endocarditis have an in-hospital survival rate of 91%.