[Long-term results in the isolated replacement of mitral and aortic valves].
This is a study of 85 valve replacements by mechanical prostheses, 41 of which were in the aortic position and 44 in the mitral position. The results were analysed from the standpoint of the immediate and late mortality, the morbidity, and thrombo-embolic complications. The influence of the severity factors (NYHA classification) on the operative risk and the late mortality has been evaluated. The maximum follow-up period was 8 years for the aortic replacements and 7 years for the mitral replacements. Actuarial graphs show that there is a 78.3% survival for aortic valve replacement and a 66% survival for mitral valve replacement. We feel that the shape of the survival curves is greatly influenced by the size of population studied. As soon as a plateau appears, the significance of the analysis is in doubt. It seems to us that calculation of the degree of confidence is essential if the good quality of the long-term results is not to be overestimated. The results of surgery must be assessed by comparing the survival curves of the operated patients with those of non-operated patients with the same risk factors. The conclusion emerges that prosthetic replacement of the mitral and aortic valves markedly improves the life expectancy of stage IV patients. We can see no indication for early surgery on the aortic valve. On the other hand, mitral valve replacement should be undertaken on stage III patients so that those with a poor life expectancy can be offered a better outlook. The way in which the mitral and aortic valve disorders carry a much greater mortality after the 6th decade should induce us to bring forward the indications for surgery in this age group in spite of the slightly greater immediate and late risk from operating on patients of this age.