La thérapie valvulaire aortique par cathéter pour une population de patients considérés à risque chirurgical plus élevé : critères déterminants de la sélection, du risque et de l'amélioration des résultats et de l'accès au cours des années

Objective: Transcatheter aortic valve intervention (TAVI) has emerged as an alternative to conventional surgical replacement of the aortic valve (SAVR) in high-risk patients (STS score ≥3%) with symptomatic aortic stenosis. Nevertheless, the selection of suitable candidates remains challenging, in part due to a paucity of data regarding performance metrics. The objectives of this thesis were: 1) to assess the rate of hospital readmission (an important performance metric) following TAVI and identify associated predictors; 2) to evaluate the performance of four commonly used frailty markers as predictors of early and late outcomes among patients undergoing TAVI and identify optimal cutoff values for risk stratification; and 3) to assess the clinical results over time of patients with aortic stenosis with a procedural indication who were discussed by a «Heart Team» in order to evaluate if TAVI and conventional surgical outcomes improve over different time periods and what are the reasons. Methods: A retrospective cohort study was conducted to assess the value of baseline comorbidities and procedural complications in predicting early and late hospital readmissions following TAVI. The Fine and Gray extension of Cox regression models was used to account for competing risks. Four frailty variables (i.e., serum albumin, 5-meter walk test, grip strength, and Katz index of independence) were assessed in a second cohort study. Associations between frailty indicators and a composite endpoint of major adverse events were assessed in logistic regression models, with optimal cutoff values for each frailty indicator identified using receiver-operating characteristics curves. Finally, 30-day mortality and post-procedural complications were examined in patients triaged in majority by a «Heart Team» between 2012 and 2019. A propensity-matched analysis was performed.        Results: We identified baseline comorbidities and procedural complications that were directly associated with early and late readmissions following TAVI. Anemia and post-operative stroke were associated with increased mortality. Among high-risk patients undergoing TAVI, serum albumin, activities of daily living, and 5 meters walk test independently predicted the 30-day composite endpoints. A new frailty model (four frailty indicators, age, and sex) was proposed and found to provide superior discrimination compared to The Society of Thoracic Surgeons risk model. Individual frailty variable cutoff values were identified. Finally, improvement in both TAVI and conventional surgical outcomes were observed over time, with a reduction in 30-day mortality (4,0% to 0,4%), stroke (2,5% to 0,9%), renal failure (3,5% to 1,5%), pneumonia (10,0% to 1,5%), and length of stay (7 to 2 days). The two interventions (TAVI and AVR) were associated with different complications and we will discuss about the possible explanations for the improvement in outcomes. Conclusion: This thesis identified simple metrics that could assist the «Heart Team» in selecting appropriate candidates with severe symptomatic aortic stenosis for TAVI, and refined cut-off values for common frailty indicators. Finally, an increased use of TAVI over the years with broadening indications resulted in a decrease in complications and mortality in patients who received a TAVI, but also patients who received a standard AVR.

Keyphrases: TAVI, Heart Team, Patients' selection, Efficiency, Frailty, Risk score