Association between type of valve prosthesis and one year mortality in IE: an analysis of 1467 patients from the International collaboration on endocarditis prospective cohort study

Purpose: Infective Endocarditis(IE) is a disease which continues to have high mortality and morbidity, including nearly half of patients requiring cardiac surgery during the acute phase of IE. There has been no large, multicenter, prospective series comparing mechanical and biological prostheses in IE. Our objectives were to describe the characteristics of patients according to the type of valve replacement(mechanical or biological), and to examine whether the type of prosthesis was independently associated with in-hospital and 1-year mortality. Methods: The International Collaboration on Endocarditis - Prospective Cohort Study is a prospective, multicenter, international registry of IE cases. Among 5,591 patients 18 years or older, 1,467 patients with definite IE were operated on during the active phase of disease and had a biological (550; 37%) or mechanical (917; 63%) valve replacement. Results: As compared to patients who received mechanical prostheses, those who received bioprostheses were older (62 vs 54 years; p<.0001), more often had a history of cancer (9% vs 6%; p=0.009), and had moderate or severe renal disease (9% vs 4%; p=0.0003). Proportion of health care-associated IE was higher in the bioprosthesis group (26% vs 17%; p<.0001). Intracardiac abscesses were more frequent in the bioprosthesis group (30% vs 23%; p=0.0044). Both in-hospital and 1-year death rates were higher in the bioprosthesis group, 20.5% vs 14.0% (p=0.0009) and 25.3% vs 16.6% (p<.0001), respectively. Only 3 variables were independently associated with the type of prosthesis implanted. Mechanical prostheses were less commonly implanted in older patients (odds ratio: 0.64 for every 10 years; 0.56 - 0.73), and in patients with a history of cancer (0.72; 0.53 - 0.98), but were more commonly implanted in mitral position (1.60; 1.29 - 2.00). In the multivariable analysis, bioprosthesis was independently associated with 1-year mortality (hazard ratio: 1.298; 1.011-1.665; p=0.041). In sub-group analysis, biologic valve replacementremained independently associated with 1 year mortality in patients less than 65 years old, but not in older patients. Conclusion: Patients with IE who receive a biologic valve replacementhave significant differences in clinical characteristics compared to patients who receive a mechanical prosthesis. Biologic valve replacementis independently associated with a higher in-hospital and 1-year mortality, a result which is likely related to patient characteristics rather than valve dysfunction.