Limitations
There are limitations to this study inherent to this type of
investigation. It is a retrospective review based on prospectively
collected data. We examined data from three surgeons performing both
types of aortic valve implantation concurrently, but there may be
remaining bias despite inverse probability weighting. Early in the
experience with SLV there was a conscious decision to place the valve in
older and sicker patients. As the outcomes were shown to be good and
experience improved, the SLV was used in a wider patient population.
There was also on ongoing learning curve and changes to the implantation
technique, as evidenced by decreasing need for PPM.