Impact of high transvalvular velocities early after implantation of Freestyle (R) stentless aortic bioprosthesis

Background and aim of the study: Stentless aortic bioprostheses have excell ent hemodynamics, although heterogeneity in gradients has been observed. Th e present study was intended to determine whether high early postoperative transvalvular velocities correlate with other measures of left ventricular outflow obstruction, whether the phenomenon is transient, and whether high velocities observed early after surgery predict differences in subsequent v alve performance or left ventricular remodeling. Methods: Sixty-eight consecutive patients who underwent implantation of Fre estyle(R) stentless aortic bioprosthesis and survived to hospital discharge underwent early postoperative echocardiography. Peak transvalvular velocit y was used to define a 'high-velocity' group, based on mean (+ 1 SD) for th e group. Mean pressure gradient, ratio of peak to proximal velocities, and effective orifice area were assessed; change in peak velocity and evidence of left ventricular mass regression were studied at one-year follow up. Results: Of 68 patients, 14 (21%) had 'high velocities' based on early post operative peak transvalvular velocity >3.0 m/s. There was a higher prevalen ce of women (64% versus 33%, p = 0.04), and both body surface area (1.79 +/ - 0.17 versus 1.95 +/- 0.20 m(2) p = 0.01) and implanted valve size (22.9 /- 2.0 versus 24.9 +/- 2.1 mm, p = 0.003) were smaller among the 'high-velo city' group. High velocity correlated with other measures of resistance to left ventricular outflow, including higher mean gradient (20.9 +/- 6.5 vers us 8.3 +/- 4.2 mmHg, p < 0.001) and lower effective orifice area (1.15 +/- 0.36 versus 1.69 +/- 0.62 cm: p < 0.001). High early postoperative velociti es persisted at one year in eight of 13 (62%) patients. Left ventricular ma ss regression occurred less often in the 'high-velocity' group (38% versus 77% of patients, p = 0.03) and was present in only one of eight (12%) patie nts in whom high velocity persisted at one year. Conclusion: High early postoperative transvalvular velocity suggests resist ance to left ventricular outflow. High velocities are transient in some pat ients, although persistence of high transvalvular velocity suggests 'prosth esis-patient mismatch' with incomplete relief of left ventricular outflow o bstruction.