Clinical Classification and Prognosis of Isolated Right-Sided Infective Endocarditis

Abstract

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.

Current profile of infective endocarditis in intravenous drug users: The prognostic relevance of the valves involved

“…IDUs have been classically related to RSIE with an incidence ranging from 0.7 to 13/1000 years [6]. Nevertheless, in the last decades, IE episodes in IDUs have decreased, being nowadays responsible for one third of all RSIE [2] and 2% to 5% of all IE episodes [3]. Our study confirms this data and also some relevant differences between RSIE and LSIE.…”

“…Several risk factors for S. aureus infections in IDUs have been reported, such as nasal colonization, contaminated drugs use, drug-use paraphernalia and drug-use environment [1]. In spite of the spread risk of antibiotic-resistant strains [1], frequency of methicillin-resistant strains in our series is low compared with other RSIE groups, such as cardiac device carriers [2], reflecting that infections in IDUs are mostly community-acquired. Unlike non-IDU patients, S. aureus seems not to be related with IE in-hospital mortality in IDUs [3,8], which may be associated with more benign course of RSIE where this microbe is predominant.…”

“…In fact, this condition represents a minor diagnostic criterion for IE. Although incidence of IE in intravenous drug users (IDUs) has decreased during the last decades [2], it is still responsible for 5% to 10% of deaths in IDUs [3]. Even though IDUs have been classically related to right-sided IE (RSIE), left-sided IE (LSIE) has been reported with similar frequency [4].…”

Right-Sided Infective Endocarditis and Pulmonary Infiltrates

“…Some of these patients have intravascular catheters as the main source of bacteremia, particularly with staphylococci, with high rates of methicillin-resistant Staphylococcus aureus (MRSA, 33%) which suggests the nosocomial nature of their infection. 9 Lastly, RSIE can also develop in patients with congenital heart diseases or in patients with surgically corrected congenital cardiac anomalies. [10][11][12] This patient group will not be covered in this review.…”

“…9 This specific population of patients comes with a higher morbidity and mortality risk since it is composed mainly of middle-aged men with multiple comorbidities and health-care related infections. Some of these patients have intravascular catheters as the main source of bacteremia, particularly with staphylococci, with high rates of methicillin-resistant Staphylococcus aureus (MRSA, 33%) which suggests the nosocomial nature of their infection.…”