Clinical classification and prognosis of isolated right-sided infective endocarditis

From an epidemiologic point of view, right-sided infective endocarditis (RSIE) affects different types of patients: intravenous drug users (IDUs), cardiac device carriers (pacemakers and implantable automatic defibrillators), and the "3 noes" endocarditis group: no left-sided, no IDUs, no cardiac devices. Our objective is to describe and compare the clinical profile and outcome of these groups of patients. Every episode of infective endocarditis (IE) consecutively diagnosed in 3 tertiary centers from 1996 to 2012 was included in an ongoing multipurpose database. We assessed 85 epidemiologic, clinical, echocardiographic, and outcome variables in patients with isolated RSIE. A bivariated comparative analysis between the 3 groups was conducted.Among 866 IE episodes, 121 were classified as isolated RSIE (14%): 36 IDUs (30%), 65 cardiac device carriers (54%), and 20 "3 noes" group (16%). IDUs were mainly young men (36 ± 7 years) without previous heart disease, few comorbidities, and frequent previous endocarditis episodes (28%). Human immunodeficiency virus infection was frequent (69%). Cardiac device carriers were older (66 ± 15 years) and had less comorbidities (34%). Removal of the infected device was performed in 91% of the patients without any death. The "3 noes" endocarditis group was composed mainly by middle-age men (56 ± 18 years), health care related infections (50%), and had many comorbidities (75%). Whereas Staphylococcus aureus were the most frequent cause in IDUs (72% vs 34% in device carriers and 34% in the "3 noes" group, P = 0.001), coagulase negative Staphylococci predominated in the device carriers (58% vs 11% in drug users and 35% in the "3 noes", P < 0.001). Significant differences in mortality were found (17% in drug users, 3% in device carriers, and 30% in the "3 noes" group; P < 0.001). These results suggest that RSIE should be separated into 3 groups (IDUs, cardiac device carriers, and the "3 noes") and considered as independent entities as there are relevant epidemiologic, clinical, microbiological, echocardiographic, and prognostic differences among them.