The Björk-Shiley valve prosthesis. Analysis of long-term evolution.

The long-term follow-up of 831 patients who underwent valve replacement with Björk-Shiley Delrin and standard Pyrolyte prostheses (341 aortic, 345 mitral, and 145 mitroaortic) between 1971 and 1980 is reviewed. The follow-up concluded in 1985. Cumulative follow-up amounted to 4724 years, with a mean of 5.68 years per patient. Data on survival were obtained in 754 patients (complete follow-up in 90.8% of cases). Perivalvular leak was the most frequent complication in aortic valve replacement, whether isolated or combined, with values significantly higher than those registered in isolated mitral replacement (p < 0.001 in both cases). No correlation was found between this complication and valve calcification, but it was statistically correlated with the size 19 model (p < 0.05). Prosthetic stenosis was more common in mitral than in aortic replacement (p < 0.001), and of the former, size 23 was that most often affected (p < 0.001). The earliest case of mitral pannus was diagnosed 20 months postsurgery, and from 45 months on this pathology was the cause of every case of stenosis. The risk of thromboembolism was similar in aortic, mitral, and double prostheses, while it was the single most frequent complication in isolated mitral replacement. Prosthetic thrombosis was triggered in all cases in which it occurred by discontinuance of anticoagulant therapy. Anticoagulant-induced hemorrhages were more frequent in double replacement than in mitral (p < 0.05) and aortic valve replacement. Endocarditis was the complication that produced the highest mortality rate in all groups; the frequency of this infection was higher among patients with double prostheses when compared with either aortic replacement (p < 0.05) or mitral replacement (p < 0.001). The risk of suffering endocarditis was correlated with the existence of active preoperative infection in patients with mitral prostheses and double prostheses (p < 0.001 in both cases). Overall morbidity was higher in the double replacement group with respect to the mitral group (p < 0.01). The rate of mortality was also higher among the double valve replacement patients when compared with both the aortic (p = 0.0002) and mitral (p = 0.006) groups.