LIMITATION OF THE STUDY
This is prospective, but observational study and, even if most variables are similar in both groups, it is not possible to reproduce the validity of a randomized study. Moreover, most of bioprostheses used are self-expandable, a well known risk factor for PPI, but their presence constant in both groups. We think that the findings of this study can be valid in general, as inflammation is a risk factor for the progression of many valvular diseases.