Author + information
- aAssistance Publique Hopitaux de Marseille, La Timone Hospital, Cardiology Department, Marseille, France
- bAix-Marseille Université, Institut de Recherche pour le Developpement, Assistance Publique Hopitaux de Marseille, Microbes Evolution Phylogeny and Infection, Institut Hospitalo-Universitaire Méditerranée Infection, Marseille, France
- ↵∗Address for correpondence:
Dr. Gilbert Habib, La Timone Hospital, Cardiology Department, Boulevard Jean Moulin, 13005, Marseille, France.
Infective endocarditis (IE) is a severe disease associated with high mortality and complications (1). Injection drug use (IDU) predisposes to IE and represents a minor diagnostic criterion in the Duke classification (2). IE in IDU has been associated with frequent recurrences (3,4), but its prognosis is still debated (5). In this issue of the Journal, Rudasill et al. (6) analyzed the trends in IE associated with IDU (IDU-IE) hospitalization and outcomes and readmissions in the United States. This work gives us the opportunity to summarize the current challenges in the management of IDU-IE.
Incidence and Clinical Features of IE in IDU
The incidence of IDU-IE is clearly increasing in the United States. In the survey-weighted sample of IE cases of Rudasill et al. (6), there were 96,344 (77.8%) non-IDU-IE cases and 27,432 (22.2%) IDU-IE cases between 2010 and 2015. The number of IDU-IE cases significantly increased between 2010 and 2015 (p < 0.001). Those in the 15- to 34-year age group faced the greatest risk, representing 37.1% of IDU-IE cases in 2010 but 46.7% of all IDU-IE cases in 2015 (p < 0.001). These results again underline the high burden of IVU related to opioid consumption, particularly in younger patients, and the need to focus our efforts to reduce drug use in this population.
Whether these trends also occur in other countries is uncertain. For instance, in three 1-year population-based surveys conducted in 1991, 1999, and 2008 in 3 French regions totaling 11 million adult inhabitants (7), total IE incidence remained stable over time, representing 35, 33, and 32 cases per million in 1991, 1999, and 2008, respectively. Although the proportion of patients with prosthetic valves and with pacemakers, hypertension, and diabetes mellitus increased, the proportion of IDU remained stable over time (5.6%, 6.3%, and 4.7% in 1991, 1999, and 2008, respectively). Although only patients age 15 to 64 years were included in the study of Rudasill et al. (6), the 22.2% reported IDU-IE cases are worrying and may alert both European and American doctors about the major importance of preventive measures in IDU. The global incidence of IDU-IE cases in Europe will be available in a few months with the results of the EuroEndo registry.
The clinical features of IDU-IE may also differ between studies. In the current study, patients with IDU-IE were significantly younger, and had lower rates of congestive heart failure, systemic hypertension, and renal failure than non–IDU-IE, like other published series (3). Unfortunately, in the current series (6), authors were not able to get information about the localization (right- or left-sided) of IE in their patients. Although right-heart IE is reported by the authors to be more frequent in IDU-IE, recent series reported a high incidence of left-heart IE in IDU (39% in the series of 66 IDU-IE reported by Ortiz-Bautista et al. , >50% in the series of Shrestha et al. , and up to 66% in our own unpublished series of 109 IDU-IE cases). These different patterns may explain different management and prognostic patterns among series, because prognosis is worse in left- than right-sided IE.
Surgical Therapy, Prognosis, and Recurrences of IDU-IE
Rudasill et al. (6) found that IDU-IE was associated with reduced mortality (6.8% vs. 9.6%; p < 0.001) but surprisingly not with higher 30- or 180-day readmission (23.8% vs. 22.9%; p = 0.077) compared with non–IDU-IE. However, both medically and surgically managed IDU-IE were more likely to be readmitted for endocarditis and drug abuse compared with non–IDU-IE.
The better short-term prognosis of IDU-IE can be explained by the young age of this population and by the more frequent right-sided localization of IE, even if not clearly proved by the current study.
One of the main issues in patients with IDU-IE is the underuse of surgery in this population. Current guidelines on the management of IE by the European Society of Cardiology and American Heart Association both recommend surgery to be performed in cases of complications of IE, including heart failure, uncontrolled infection, and prevention of systemic embolism (8–10). Although in the current series, patients with IDU-IE received valve surgery at equivalent rates to patients with non–IDU-IE, this reported surgical rate (11.5%) is far lower than those reported in current series from reference centers on IE (5,7). This is clearly related with the concern about reinfection or recurrence associated with persistent drug abuse in this population. Among the IDU population, patients are at risk of recurrent infection from continued drug use (4). In 1 series (3), between 3 and 6 months after operation for IE, patients with IDU-IE had a hazard of death or reoperation that was about 10 times that of patients who do not inject drugs. This agrees with our own experience in which in-hospital mortality is very low (7.3%) but 1-year mortality is high (15%) as well as the risk of 1-year recurrence (16.5%).
IDU-IE: What Should We Do in the Future?
Several issues remain unsolved in IDU-IE, including its incidence in different parts of the world, the beneficial effect or lack of effect of early surgery in this population, the value of valve repair compared with valve replacement, and the respective prognosis of left-sided versus right-sided IDU-IE.
Finally, although initial mortality seems to be lower in patients with IDU-IE, their long-term mortality is unknown, and further studies are needed to assess the real benefit of surgery in this population, particularly in the subgroup of patients with persisting drug use.
As stated by the authors, increased focus on addiction treatment and social support following hospital discharge is mandatory to reduce the risk of recurrent endocarditis. For this purpose, the early implication of addiction treatment centers will be the next challenge.
This task can be performed in reference centers within specialized endocarditis teams (8).
↵∗ Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2019 American College of Cardiology Foundation
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