Objectives: The objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to their hemodynamic behavior during exercise.
Background: Stentless aortic bioprostheses have better hemodynamic performances at rest than stented bioprostheses, but very few comparisons were performed during exercise.
Methods: Thirty-eight patients with normally functioning stentless (n = 19) or stented (n = 19) bioprostheses were submitted to a maximal ramp upright bicycle exercise test. Valve effective orifice area and mean transvalvular pressure gradient at rest and during peak exercise were successfully measured using Doppler echocardiography in 30 of the 38 patients.
Results: At peak exercise, the mean gradient increased significantly less in stentless than in stented bioprostheses (+5 +/- 3 vs. +12 +/- 8 mm Hg; p = 0.002) despite similar increases in mean flow rates (+137 +/- 58 vs. +125 +/- 65 ml/s; p = 0.58); valve area also increased but with no significant difference between groups. Despite this hemodynamic difference, exercise capacity was not significantly different, but left ventricular (LV) mass and function were closer to normal in stentless bioprostheses. Overall, there was a strong inverse relation between the mean gradient during peak exercise and the indexed valve area at rest (r = 0.90).
Conclusions: Hemodynamics during exercise are better in stentless than stented bioprostheses due to the larger resting indexed valve area of stentless bioprostheses. This is associated with beneficial effects with regard to LV mass and function. The relation found between the resting indexed valve area and the gradient during exercise can be used to project the hemodynamic behavior of these bioprostheses at the time of operation. It should thus be useful to select the optimal prosthesis given the patient's body surface area and level of physical activity.