Introduction
The selection of the type of valve, bioprosthetic valve (BV) or mechanical valve (MV), in patients who need valve replacement is an important decision that seriously influences the quality of life of patients, who should be actively involved in this choice.1 Several factors should be considered for this decision, mainly thrombogenicity, life expectancy and the risk of reoperation. Because of thrombogenicity, mechanical prostheses require lifelong anticoagulation and expose the patient to both bleeding risk and thrombus formation, particularly when anticoagulation is not well managed. On the other hand, mechanical prostheses have a longer lifespan, reducing the risk of reoperation that is the main limitation to BV implantation. BV duration is considered to be on average 15 years when implanted in elderly patients; however, the lifespan of these valves is shorter among younger patients who show accelerated valve deterioration.2 For this reason, clinical guidelines recommend the use of MV prosthesis in young patients, indicating the age of less than 60 years as the optimal age for the implantation of this kind of valve. However, uncertainty still exists for the choice of the type of valve for patients in the lifespan between 60 and 70 years, and recommendations differ from European and American guidelines.1 3 European guidelines recommend to use BV after the age of 65 years,1 with uncertainty for patients aged 60–65 years. Instead, American guidelines recommend the use of BV after the age of 70 years, with an interval of uncertainty for patients between 60 and 70 years.3 The use of BV has significantly increased over the last years. In the UK the number of BV implantations grows from 65.4% to 77.8% between 2004 and 2009.4 Similarly, the rate of BV implantation increased in the Netherlands between 1995 and 20105 and in the USA between 1999 and 20116 even among patients aged 55–64 years, despite the different guideline recommendations.1 3
Moreover, with respect to the need for long-life anticoagulant treatment, it should be noted that a large number of elderly patients develop other indications to anticoagulation, mainly atrial fibrillation (AF), so losing the advantages of carrying a BV.2 According to the longer life expectancy that has been recorded in Western countries in the recent years, the incidence of AF is progressively growing particularly among patients with heart valve diseases, leading to an increasing need for anticoagulation to prevent thromboembolic stroke. Therefore, a growing number of patients who received BV implantation did not stop anticoagulation after the first few months after surgery, but are maintained on long-term treatment. We have conducted an observational, retrospective, multicentre study among Italian Thrombosis Centers on patients on long-term anticoagulation for the presence of prosthetic heart valves to obtain information on the adverse events occurring during follow-up. In this study, we report data on patients with BV on long-term vitamin k antagonist (VKA) treatment for the presence of AF or other indications, with the aim of evaluating the risk of undergoing reoperation and the rate of bleeding and thrombotic events during anticoagulation.