Data Extraction
Data extraction was performed in duplicate with Microsoft Excel (Microsoft Office 2010, Microsoft, Redmond, WA, USA) by two of the authors (BA and JE) according to the guidelines for reporting mortality and morbidity after cardiac valve interventions (9). Events were not included in our database when adherence to the reporting guidelines could not be ascertained. For each article with missing information on important variables, the corresponding author was requested to provide the missing data. Institutional review board approval was not applicable for this study, and informed consent was waived. An overview of extracted variables is presented in Supplementary file 2.