[Aortic valve replacement with Starr-Edwards and Björk-Shiley prosthesis. Long term results and statistical analysis of some risk factors (author's transl)].

285 patients who underwent aortic valve replacement between 1972 and 1977 have been studied. 197 patients had a Starr-Edwards prosthesis and 88 patients had a Björk-Shiley prosthesis, both groups presented similar risk factors. The follow-up varied between a period of 6 months minimum and 72 months maximum, the mean period is 3.6 years. The statistical results have been realized based on the multi-factor analysis (cluster) which were the basis to define the homogeneous groups of patients with the Starr prosthesis and the Björk prosthesis. One may observe the best survival percentage after 72 months from surgery date in patients with the Björk prosthesis comparing them with those patients who underwent aortic valve replacement with the Starr prosthesis (resp. 93 and 71%). The difference is important from the statistical point of view. The embolic incidence after such a period is nearly equal (16% for Björk and 14% for Starr). The cluster analysis of the considered parameters (age, duration of symptoms before surgery, NYHA class, C/T) did not evince real and proper risk factors such to condition, at long term, the results even if differences in mortality and in embolic incidence, with regards to the relation with NYHA class and symptoms; duration, have been observed. One may conclude that one of most important risks derives form the type of used prosthesis.