[First results from the OBSERVANT II study: clinical characteristics of patients with aortic stenosis undergoing transcatheter treatment with new generation devices]

Background: The OBSERVANT study evaluated the medium and long-term outcomes in patients undergoing transcatheter aortic valve implantation (TAVI) versus surgical aortic valve replacement obtaining comparative effectiveness results at least for the first-generation devices. The OBSERVANT II study enrolled a new series of TAVI procedures to evaluate whether the use of new-generation devices has modified outcome differences recorded in the OBSERVANT study. The aim of this paper is to describe the clinical characteristics of the OBSERVANT II population and compare them with those of the OBSERVANT population. Methods: OBSERVANT II is a prospective multicenter observational study, which enrolled patients with severe aortic stenosis, who underwent a TAVI procedure in 30 Italian centers from December 2016 to September 2018. Clinical, anatomical and procedural information was recorded for each patient as well as procedure characteristics and any periprocedural outcomes. An administrative follow-up will allow to obtain information on medium and long-term outcomes. Results: The enrolled population consists of 3001 patients with a mean age similar to that recorded in OBSERVANT (81.7 ± 6.3 vs 81.9 ± 6.2 years; p=0.336). OBSERVANT II patients show a lower prevalence of several morbid conditions than OBSERVANT patients (i.e. chronic obstructive pulmonary disease, coronary artery disease, peripheral arterial disease, etc.), though having very similar mean values of EuroSCORE II (7.2 ± 7.6% vs 7.4 ± 7.9%; p=0.558). According to three EuroSCORE II risk classes (≤3; 3-7; ≥7), the in-hospital mortality rates for patients enrolled in the two studies are 1.0% vs 2.0% (p≤0.000), 1.4% vs 4.1% (p<0.000) and 2.4% vs 7.7% (p<0.000), respectively. Conclusions: The first results of the OBSERVANT II study show that patients undergoing TAVI with new-generation devices are elderly, have a lower risk profile than patients enrolled in the OBSERVANT study but comparable mean values of EuroSCORE II. The in-hospital mortality rate for patients enrolled in the OBSERVANT II study is lower than that recorded in the OBSERVANT study across all the EuroSCORE II risk classes.