Multivariate analysis of survival after malfunctioning biological and mechanical prosthesis replacement

Results of valvular reoperations depend on extrinsic and patients' intrinsic risk factors. New prosthetic substitutes continue to appear and the clinical effect is difficult to evaluate. Randomized studies are limited by patient selection and follow-up time. We followed the patient-centric outcome research applied to a large database of valvular operations.

Between January 1, 1970 and January 1, 1995 755 patients underwent one reoperation, 96 a second reoperation, and 12 a third reoperation. On January 1, 1996 a common closing date follow-up was obtained in 98.7% of reoperated patients. Multivariable analysis in the hazard domain was applied to obtain an upgradable model of survival that could be used for predictions and treatment comparison.

Postoperative death hazard showed an early phase merging within 6 months with a constant low hazard phase. The survival proportion was 0.65 (70% CL, 0.63 to 0.67) at 5 years, 0.51 (70% CL, 0.49 to 0.53) at 10 years, 0.47 (range, 0.44 to 0.49) at 15 years, 0.42 (70% CL, 0.39 to 0.46) at 20 and 25 years. Significant incremental risk factors for early mortality were reoperative era 1970 to 1980 (hazard ratio = 2.8), reoperation number (hazard ratio = 1.9), heart penetration on surgery (hazard ratio = 7.6), emergent operation (hazard ratio = 5.8), urgent operation (hazard ratio = 2.1), prosthetic thrombosis (hazard ratio = 2.4), acute prosthetic endocarditis (hazard ratio = 3.0), acute endocarditis of the natural valve at antecedent operation (hazard ratio = 3.2), original floppy valve pathology (hazard ratio = 3.2), and mitroaortic replacement (hazard ratio = 5.7). Isolated mitral reoperation had a lower risk (hazard ratio = 0.5). Significant incremental risk factors for constant phase were: operative era (1970 to 1980) (hazard ratio = 2.0), congestive heart failure (hazard ratio = 2.6), reoperation on tricuspid valve after previous mitral insertion (hazard ratio = 4.9), reoperation for recurring dehiscence (hazard ratio = 4.6), double-valve procedure (hazard ratio = 1.6), coronary artery bypass graft (hazard ratio = 2.7), aortic root disease at original operation (hazard ratio = 2.1), older operative age (hazard ratio = 1.1). Use of bileaflet prosthesis was found to decrease significantly (p = 0.0002) the death risk (hazard ratio = 0.2).

There is no late uprising hazard, and surviving patients remain exposed to a low risk of death (4% of patients per year). Considering simultaneously the confounding from operative age and operative era and the many concomitant risk factors, survival appears favorably influenced by use of bileaflet valves on reoperation.