Quality of evidence
Through our risk of bias assessment of the included studies, we determined that evidence of the 2 randomized controlled trials were of robust quality, with no severe risk of bias associated with the design of the studies12,13 (Figure 2). For the observational studies14-17, apart from high risk of bias in confounding factors and patient selection that are typical of studies with retrospective nature, we determined that the evidence provided by these studies (and the included studies overall) was still of an acceptable quality (Table 1).
Of the 6 included studies, 2 were randomised control trials12,13 and 4 observational studies14-17. In 2 of the observational studies16,17 included were only participants who underwent FFR-guided CABG (single-arm studies). The data from these studies was used to carry out a pooled analysis.