Does valve design impact the maximum implantable bioprosthetic diameter? A prospective, multicenter observational study.

BACKGROUND AND AIM OF THE STUDY: The effective orifice area index (EOAI) of bioprosthetic aortic valves portends the long-term left ventricular mass regression and longevity of patients with aortic valve disease. The manufacturers' stated EOA per valve size may lead to inaccurate comparisons if the valve design allows a different-sized prosthesis to be implanted for any given true annular diameter. This prospective, observational study was undertaken in order to evaluate the relationship between the true annular diameter and the different sizers that can be accommodated in any given annulus, along with the resultant size and type of bioprosthesis implanted.

METHODS: An interim analysis was undertaken of 318 aortic valve replacement patients among a study group of 1,850 patients undergoing surgery at 21 U.S. sites between January 2004 and October 2006. Following valve excision and annular debridement, the true annulus size was determined using a Medtronic universal sizer (UNIV), followed by the largest Medtronic Hancock II/Mosaic (MM) and Edwards Perimount (EP) standard aortic sizer which fitted safely, and the findings recorded. Details of the actual bioprostheses implanted were recorded, and outcomes with 247 MM or EP implants were analyzed (71 patients received other prostheses).

RESULTS: The largest fitting trial sizer was smaller than the UNIV sizer in 108 patients (34%) using the EP sizer compared to 17 patients (5.3%) using the MM sizer (p < 0.001). Conversely, the largest fitting trial sizer was at least one size larger than the true annular diameter in 123 patients (38.7%) using the MM sizer compared to 17 patients (5.3%) using the EP sizer (p < 0.001). In total, 115 of 130 (88.5%) MM implants compared to 59 of 119 (49.6%) EP implants were equal to or greater than the UNIV (p < 0.001).

CONCLUSION: For any given true annular diameter, a larger MM sizer and implanted prosthesis versus EP can be accommodated, which may explain the variation in the advertised EOA.