EARLY EXPERIENCE WITH STENTLESS VERSUS STENTED VALVES

Background The Toronto stentless porcine valve (SPV) was designed to i mprove hemodynamics after aortic valve replacement by maximizing avail able flow area in comparison to stented valves (STD). Methods To asses s possible hemodynamic differences between STD and SPV, 59 patients un dergoing isolated aortic valve replacement (+/- coronary artery bypass graft) were prospectively evaluated by preoperative and 3- to 6-month postoperative echocardiography. Among these, 23 patients received a S TD, whereas 36 received the Toronto SPV. Results The mean size (mm) of SPV implanted was larger (SPV, 26.6 +/- 2.1; STD, 24.0 +/- 2.9; P=0.0 002). Patients receiving STD valves were older and had a higher preval ence of coronary artery disease and congestive heart failure. There we re no preoperative differences in left ventricular mass index (g/mo(2) ), peak or mean pressure gradients (mmHg), effective orifice area (cm( 2)), extent of fractional shortening (%), or velocity of circumferenti al shortening (cf/sec). ANOVA demonstrated a significant reduction in left ventricular mass index at 3 to 6 months (P=.0001) but no differen ces in left ventricular mass index regression between groups (STD, -28 .8 +/- 37.5; SPV, -31.2 +/- 32.4; P=.36). Effective orafice area was i ncreased postoperatively (P=.0001), particularly among SPV cases (STD, 1.5 +/- 0.4; SPV, 1.9 +/- 0.7; P=.01). Postoperative left ventricular mass index and mean pressure gradient were reduced (P=.0001) but did not differ between groups. Fractional shortening and velocity of circu mferential shortening were greater in the SPV patients at 3 to 6 month s after aortic valve replacement (P=.0004 and .0001, respectively), an d an interactive effect was seen between time and prosthetic group (P= .0028 and .032, respectively). Conclusions In a consecutive series of patients, we identified no hemodynamic differences between STD and SPV , although ventricular function improved after SPV. Because of the non randomized nature of the study, selection bias may have accounted for some of the observed results. A prospective, randomized trial is neces sary to determine the hemodynamic advantages, if any, of the SPV valve .