Quantifying infective endocarditis risk in patients with predisposing cardiac conditions

Abstract

Aims: There are scant comparative data quantifying the risk of infective endocarditis (IE) and associated mortality in individuals with predisposing cardiac conditions.

Methods and results: English hospital admissions for conditions associated with increased IE risk were followed for 5 years to quantify subsequent IE admissions. The 5-year risk of IE or dying during an IE admission was calculated for each condition and compared with the entire English population as a control. Infective endocarditis incidence in the English population was 36.2/million/year. In comparison, patients with a previous history of IE had the highest risk of recurrence or dying during an IE admission [odds ratio (OR) 266 and 215, respectively]. These risks were also high in patients with prosthetic valves (OR 70 and 62) and previous valve repair (OR 77 and 60). Patients with congenital valve anomalies (currently considered 'moderate risk') had similar levels of risk (OR 66 and 57) and risks in other 'moderate-risk' conditions were not much lower. Congenital heart conditions (CHCs) repaired with prosthetic material (currently considered 'high risk' for 6 months following surgery) had lower risk than all 'moderate-risk' conditions-even in the first 6 months. Infective endocarditis risk was also significant in patients with cardiovascular implantable electronic devices.

Conclusion: These data confirm the high IE risk of patients with a history of previous IE, valve replacement, or repair. However, IE risk in some 'moderate-risk' patients was similar to that of several 'high-risk' conditions and higher than repaired CHC. Guidelines for the risk stratification of conditions predisposing to IE may require re-evaluation.

Keywords: Antibiotic prophylaxis; Guidelines; Incidence; Infective endocarditis; Predisposing conditions; Prevention; Risk; Risk quantification; Risk stratification.

Figure 1

Incidence of infective endocarditis in England from January 2000 to March 2015. (A) Incidence of infective endocarditis admissions. (B) Incidence of infective endocarditis admissions where the patient dies during the admission.

Figure 2

Five-year risk (odds) of developing infective endocarditis or dying during an infective endocarditis admission in different cardiac conditions. *Excluding recurrent infective endocarditis within 180 days of the original episode.

Figure 3

Five-year risk (odds) of developing infective endocarditis or dying during an infective endocarditis admission stratified by age and gender. Gender reference population = female, age reference population = 50–59 years.

Figure 4

The Kaplan–Meier survival curves for infective endocarditis-free survival (A–C) and death during an infective endocarditis admission-free survival (D–F), for each condition. These demonstrate the curves for patients with ‘high risk’ (A and D), ‘moderate risk’ (B and E) and ‘unknown risk’ (C and F) as defined in the ‘Methods’ and by the European Society for Cardiology and American Heart Association (see Supplementary material online, Table S1). For scale and ease of comparison, the previous infective endocarditis population (the highest risk condition) is included in each panel. **Infective endocarditis reoccurrence within 180 days of the original episode has been excluded in the group with previous infective endocarditis. CHC, congenital heart condition; VAD, ventricular assist device; NNH, 5-year number needed to harm; NC, not calculable.