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.