Native and prosthetic valve infective endocarditis: clinicopathologic correlation and review of the literature

The incidence of infective endocarditis is 1.5-4.95 cases per 100,000 individuals per year, with a mortality of 14-46% 1-year post infection. The management and decision to operate on selected patients remains controversial. Our study reviews cases of native and prosthetic valve endocarditis in a surgical population, in an attempt to identify and compare clinical and microbiologic features between the two groups. In addition, we compared our findings with other published series to identify if there are changes with these parameters over time.

A retrospective analysis of patient records at one institution over an 11-year period identified cases of explanted native (NVE) and prosthetic (PVE) valves with confirmed infective endocarditis (IE) on pathological analysis. Patient records were reviewed to identify patient demographics, risk factors, microbiology and outcomes. Gross features and histological sections were reviewed in all cases.

Two hundred and nine valves were explanted over the study period, 164 of which were native actively infected valves (average age 50.7 + 16.4 years, 77% of males) and 45 prosthetic actively infected valves (average age 55.2 + 16.2 years, 71% of males). Prominent risk factors in the NVE group were bicuspid aortic valve, dental procedures and intravenous drug use, while rheumatic heart disease and diabetes mellitus were most common in the PVE group. Streptococcus and staphylococcus were the most common organisms in both groups. In-hospital mortality was not significantly different between the two groups.

Surgical intervention remains a part of the management of IE. Despite early recognition and advanced surgical techniques, risk factors have not dramatically changed between the other reviewed studies (patients enrolled from 1978-2004), with the exception of diabetes mellitus becoming more prevalent over time. In addition, despite the change of preprocedural antibiotics prior to dental and other procedures, there does not appear to be an increase in IE cases with previous procedural intervention in our cohort compared to others series, which were published before 2008. Mortality in our cohort was not statistically significant between the NVE and PVE groups, and may be due to careful patient selection for redo surgery in the PVE group. Compared to previous studies, mortality rates remain the same over the last decade.