Epidemiology
Infective endocarditis (IE) is becoming more frequent.[17] The online NHS for England Hospital Episode Statistics (HES) reported 10,097 finished consultant episodes for acute and subacute endocarditis during 2019-20 compared with 3969 during 2009-10. Health & Social Care Information Centre: HESonline Opens in new window In the US, one study found that between 2000 and 2011, the incidence of IE increased from 11 per 100,000 to 15 per 100,000.[18] Between 2000 and 2020 in Europe, IE incidence increased 4.1% per year.[17] Another study looking at the incidence of drug use-related IE between 2002 to 2016 found the overall incidence of IE increased from 18 per 10,000 to 29 per 10,000, and the incidence in those with drug use-related IE increased from 48 per 10,000 to 79 per 10,000.[19] In-hospital mortality from IE is 15% to 30%.[20][21]
In developed countries, IE is more common in the setting of previous valve surgery or as a consequence of iatrogenic or nosocomial infection, whereas chronic rheumatic disease is an uncommon antecedent. Rheumatic heart disease remains the leading cause of IE in developing countries.[22][23]
IE in pregnancy is rare and is associated with intravenous drug use and pre-existing cardiac disease and, in particular, mechanical prosthetic valves, where the incidence is higher than in the general population.[24] Maternal mortality reaches 18% to 22% and is usually due to embolic events or heart failure.[6][24]
Risk factors
The National Institute for Health and Care Excellence in the UK classifies a patient as being at increased risk of developing IE if they have structural congenital heart disease, including surgically corrected or palliated conditions, but excluding isolated atrial septal defect, fully repaired ventricular septal defect, fully repaired patent ductus arteriosus, and closure devices that are judged to be endothelialised.[36]
The European Society of Cardiology classifies a patient as being at highest risk of developing IE if they have untreated cyanotic congenital heart disease, or congenital heart disease that has been repaired with a prosthetic material (including valved conduits or systemic-to-pulmonary shunts).[6]
The prevalence of congenital heart disease in adults has increased as a result of improved treatment options in childhood.[37]
Development of a cardiac valvulopathy post-heart transplant is regarded as one of the conditions associated with the highest risk of adverse outcome from endocarditis.[38]
Non-heart organ transplants are also associated with increased risk of IE. The highest risk organ transplants are kidney and liver, with enterococci, gram-negatives, and Aspergillus being the most common infecting organisms.[39][40]
presence of cardiac implanted electronic device or intravascular catheters (e.g., for haemodialysis)
The prevalence of MVP in the general population is high, and patients with MVP have a three- to eight-times increased risk of IE compared to people with structurally normal hearts.[42]
MVP with concomitant mitral regurgitation places patients at greater risk.[42]
There is much debate regarding the efficacy of prophylaxis in patient with non-regurgitant MVP.[42]
These patients are at greater risk of developing acute Staphylococcus aureus endocarditis.[3] One in every 10 invasive staphylococcal infections in the US is attributable to intravenous drug use.[3]
Although tricuspid involvement has been shown to be significantly more frequent in endocarditis associated with intravenous drug use compared with no intravenous drug use, one study found that left-sided endocarditis was still more common than right-sided endocarditis in both groups.[14]
These patients have been shown to have worse clinical outcomes irrespective of drug use following surgery.[14]
Endocarditis is a serious complication of chronic Q fever. It typically affects middle-aged men with a history of significant exposure to animals and usually occurs in patients with pre-existing valvular disease or who are immunocompromised.[44] Clinical presentation of chronic Coxiella burnetii endocarditis should be strongly considered in the differential diagnosis of culture negative endocarditis. A high index of suspicion in at-risk people with a fever of unknown origin, combined with serological testing, ensures timely diagnosis.[44]
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