Real Structural Valve Deterioration of the Mitroflow Aortic Prosthesis: Competing Risk Analysis

Abstract

Introduction and objectives: The Mitroflow aortic prosthesis is a bovine pericardial bioprosthesis specially designed to increase the valve area in relation to its size. There is controversy regarding the pattern of structural valve deterioration (SVD). Our aim was to determine the cumulative incidence of SVD, risk factors influencing its occurrence, and its impact on mortality.

Methods: A total of 1028 patients were clinically and echocardiographically followed up. Because the study population was elderly and had heart disease, we used a competing risk analysis.

Results: The percentage of patients with SVD at 5 years was 4.22% (95%CI, 2.96-5.81) and was 15.77% at 8 years (95%CI, 12.46-19.43). The incidence was higher for small valves (19mm and 21mm) reaching 6.43% at 5 years (95%CI, 4.48-8.84) and 20.06% at 8 years (95%CI, 15.53-25.01). Severe patient-prosthesis mismatch (PPM) influenced the incidence of SVD (_sHR, 3.53; 95%CI, 2.20-5.66; P < .001) but moderate PPM had no impact. The most powerful predictor of mortality was the presence of SVD (HR, 4.59; 95%CI, 2.91-7.22; P < .001).

Conclusions: This study used a definition based on the increase in the transprosthetic gradient and found a higher incidence of SVD of the Mitroflow prosthesis than that reported by other series, especially for sizes 19mm and 21mm and in patients with severe PPM. The incidence of SVD increased exponentially from the fifth year after implantation and its occurrence led to a 4.5-fold increase in the risk of death.

Keywords: Aortic valve replacement; Bioprosthesis; Bioprótesis; Degeneración estructural valvular; Recambio valvular aórtico; Structural valve deterioration.