• Sophie Newton and Steven Hunter.
• St George's University of London, London, UK. sophielnewton@gmail.com
• Interact Cardiovasc Thorac Surg. 2010 Dec 1; 11 (6): 784-8.

AbstractA best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'in patients undergoing a surgery for endocarditis is a biological valve or mechanical valve superior for achieving long-term low rates of reinfection?' Altogether more than 41 papers were found using the reported search, of which nine represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Out of the studies that include statistical comparisons, in mechanical valve replacement the average endocarditis recurrence rate ranged from approximately 3 to 9% and in biological valves from approximately 7 to 29%. Out of the studies that specifically compared the outcomes of the two valves, 50% concluded there to be no significant difference when separated from other risk factors and 50% recommended a mechanical valve for lower recurrence and higher survival rates. The Euro Heart Survey found that 63% of valve replacements were mechanical, due to young age (90%) and physician preference (75%) and only 21% bioprosthetic. Current guidelines from American College of Cardiology/American Heart Association (ACC/AHA) recommend a mechanical valve in patients <65 years old and a bioprosthetic valve if >65, without risk factors for thromboembolism, but this is based on class II evidence (conflicting evidence or opinion). These guidelines are not specific to patients with infective endocarditis, so it is vital to review the literature related to this. Three of the studies in the search specify that for patients under 60-65 years old, a mechanical valve has greater benefit, but this was not found to be true for the over 65 years. It can be concluded that for patients under 65 years old, a mechanical valve may offer greater freedom from reoperation and increased long-term survival when compared to a bioprosthetic valve (assuming no other co-morbidities), although this divide is narrowing with the use of newer generation bioprosthetic valves and has to be off-set against potential bleeding risks. For patients over 65 years, other important variants need to be considered including patient choice, correct protocols of antibiotics and radical debridement.

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