Hancock versus stentless bioprosthesis for aortic valve replacement in patients older than 75 years

Stented aortic bioprostheses are routinely used in elderly patients. The stent, however, is obstructive and implies several hazards. Stentless aortic valves appear to be hemodynamically advantageous. However, their implantation is longer and technically more demanding, and durability is still under investigation.

Between January 1993 and December 1996, 77 patients (28 men) were prospectively randomized to undergo aortic valve replacement using the Hancock valves (group A: 40 patients, 16 men; age, 77+/-3 years; body surface area, 1.7+/-0.17 m2) or a stentless bioprostheses (group B: 37 patients, 12 men; age, 76+/-2 years; body surface area, 1.7+/-0.15 m2; Biocor, 17; Toronto SPV, 20). Preoperative variables were not significantly different between the two groups. Bypass time was 123+/-46 versus 133+/-51 minutes, and aortic cross-clamp time was 83+/-26 versus 95+/-24 minutes for group A and group B, respectively (not significant). Seven patients in group A (17.5%) and 5 in group B (13.5%) had enlargement of the aortic annulus. Valve size normalized to body surface area was 13.7+/-1.5 versus 14.1+/-1.6 mm/m2 for group A and group B, respectively (not significant). Eleven patients in group A (27.5%) and 5 in group B (13.5%) had concomitant myocardial revascularization.

Overall perioperative mortality was 5% in group A (low cardiac output in 2 patients), and 8% in group B (low cardiac output in 1; major neurologic event in 2). Follow-up is 97% complete (group A, 14.5+/-10 months; group B, 18.5+/-12 months). One patient in group B died at 28 months of myocardial infarction. Actuarial survival at 12 and 24 months is 92% versus 91% and 92% versus 81% for group A and group B, respectively. At 6 months, patients in group A showed a peak transaortic gradient of 25+/-7 versus 20+/-9 mm Hg in group B. Progressive regression of left ventricular mass expressed as a percentage of preoperative value was 10.5% and 19% for group A and group B at 1 year postoperatively (not significant).

Stentless valves represent a valuable alternative to conventional prostheses in patients older than 75 years, although no great advantages with their use emerge from this study. Continued evaluation particularly with regard to evidence of left ventricular remodeling and valve degeneration in the long term is warranted.