Primary tissue valve degeneration in glutaraldehyde-preserved porcine bioprostheses: Hancock I versus Carpentier-Edwards at 4- to 7-years' follow-up.

In the 32-month period between April, 1978, and December, 1980, 292 patients, divided into two equal groups, received a glutaraldehyde porcine bioprosthesis--either Hancock or Carpentier-Edwards (CE)--as mitral valve substitute. Every patient receiving a mitral porcine xenograft during that time was included in the study. The type of bioprosthesis was always selected by the surgeon and not randomly. Preoperative clinical characteristics, associated surgical procedures, valve implantation sizes, and follow-up data showed no relevant differences between the two groups. There were three instances of primary tissue failure in the Hancock group and six in the CE (linearized rates of 0.49 and 0.97 events percentage of patient/years, respectively). Mean duration of explanted valves and microscopic findings were similar in both groups. Primary tissue failure was more frequent in patients under 40 years of age in both groups, although differences were not statistically significant. A marginally significant trend toward greater incidence of tissue failure in patients of 40 years of age and older was seen in the CE group when compared with the Hancock group. Actuarial survival of the bioprostheses free from primary tissue failure was 6.5 years of 95 +/- 3% (mean +/- standard error) for Hancock and 84 +/- 9% for CE (p = NS). No significant difference in terms of durability has been found between the two most popular glutaraldehyde porcine bioprostheses, although the behavior of the CE in patients older than 40 years should be reassessed in a study with a larger number of patients and a longer follow-up period.