Prognosis after Autograft and Allograft Aortic Root Replacement. Evidence-based Estimates using Meta-analysis and Microsimulation.

The goal of this thesis was to develop an objective and valid methodology to support the choice for a particular aortic valve substitute in the individual patient, with a primary focus on autografts and allografts. This includes the important question: Can patient-specific recommendations be made with regard to the preferred valve substitute for patients requiring aortic valve replacement, based on the methodology described in this thesis? This question will be discussed by: (1) Commenting on the current clinical evidence on outcome after aortic root replacement with autografts and allografts, (2) Critically evaluating the methods of meta-analysis and microsimulation with regard to their ability to predict outcome after aortic valve replacement, (3) Comparing calculated outcome after autograft versus allograft aortic root replacement, and versus other valve substitutes, and finally to actual situations. In conclusion, clinical experience with autograft and allograft aortic root replacement turned out to be limited, both with regard to number of patients and duration of follow-up. Meta-analysis and microsimulation provide an objective and flexible tool to overcome these limitations and allow calculations of long-term prognosis after autograft and allograft aortic root replacement based on current limited evidence. Using this methodology, detailed information can be obtained on the determinants of prognosis, providing improved insight into outcome after autograft and allograft aortic root replacement. However, both meta-analysis and microsimulation have their limitations and the output of the microsimulation model strongly depends on the quality of the input and the assumptions of the model. Continuous refinement and updating of the microsimulation model are therefore necessary to provide objective and valid estimates of outcome after aortic valve replacement in the future. Furthermore, education of clinicians on the methodology of microsimulation is essential for successful application in clinical practice. An internet application of the model should become available in the near future for easy access use by clinicians.

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