OBSERVANT II: OBservational Study of Effectiveness of transcatheter aortic valve implantation with new geneRation deVices for severe Aortic steNosis Treatment. Study protocol

BACKGROUND: The rapid spread of transcatheter aortic valve implantation (TAVI) for the treatment of severe symptomatic aortic stenosis in the last decade in Italy has led to a gradually increasing use of TAVI procedures also in patients potentially eligible for aortic valve replacement (AVR). For this subset of patients, the OBSERVANT study (2011-2012) evaluated the short- and medium term outcome of TAVI vs AVR, at least for the first generations of TAVI devices, but failed to gather information on all the technological innovations occurred in recent years. The launch of a phase II of the study will allow to recruit a new series of TAVI, with different risk profiles compared with the historical OBSERVANT TAVI cohort, in order to assess whether and how much the use of new-generation devices mitigate the differences in outcomes recorded in the OBSERVANT study. METHODS: OBSERVANT II is an observational multicenter, prospective, cohort study collecting data on patients with severe symptomatic aortic stenosis undergoing TAVI in Italian hospitals since December 15, 2016, for at least 12 months. For each patient, data on demographic characteristics, health status, type of intervention and presence of comorbidities will be collected. Mortality and incidence of in-hospital major adverse cardiac and cerebrovascular events (MACCE) within 36 months of intervention will be the primary adverse outcome. Secondary outcomes will include 30-day mortality and the incidence of MACCE at 12 and 24 months. The statistical hypotheses were formulated considering the results from the OBSERVANT study. Testing these hypotheses will require the recruitment of at least 823 new TAVI. The risk/propensity-adjustment techniques will be used to comparatively evaluate the effectiveness of TAVI vs AVR. EXPECTED RESULTS: Safety and efficacy profiles of the new-generation TAVI prosthesis; comparative effectiveness of the new TAVI prosthesis as compared to TAVI procedures of the OBSERVANT historical cohort; comparative effectiveness of the new TAVI prosthesis as compared to AVR procedures of the OBSERVANT historical cohort. CONCLUSIONS: The results of OBSERVANT II will provide information on the effectiveness of TAVI employing new-generation devices and will be a valuable support to give professionals and policy makers evidence-based results useful for decision-making processes