The OSTIAL Study (Optimization of Stent Placement in Aorto-ostial Lesions)

Overview

Aorto-ostial coronary lesions present a significant challenge during coronary angioplasty. This is due to the difficulty of precisely identifying the aorto-ostial plane and the frequent instability of the guiding catheter during stent deployment. Despite the angiographic appearance being deemed optimal, several studies have shown a high rate of suboptimal stent positioning at the ostium when subsequent coronary CT angiography (CCTA) assessment is performed. This suboptimal positioning may be linked to incomplete ostial coverage, which could increase the risk of in-stent restenosis. It may also be linked to excessive stent protrusion into the aorta, which could compromise future procedures, particularly in the context of transcatheter aortic valve replacement. The "Floating Balloon" (FB) technique has been developed to improve system stability and to reliably mark the aorto-ostial landing zone (AOLZ). A previous study demonstrated the feasibility and accuracy of this technique. The aim of the current study is to assess the clinical effectiveness of the Floating Balloon. Although this technique is already in use, no study has yet conducted a systematic assessment of stent positioning using CCTA. The study utilised a combined retrospective-prospective approach to comprehensively evaluate the incidence of suboptimal stent positioning associated with the Floating Balloon technique. This evaluation was conducted by systematically comparing patient outcomes between those treated with the FB and those treated without the FB. The study employed CCTA as a key tool to assess stent position, ensuring a precise analysis of the data. To achieve this, it is recommended that follow-up data from patients who have already undergone the FB procedure and had their stent position assessed via CCTA (retrospective component) be analysed, while also enrolling new patients and randomizing them into FB and non-FB groups (prospective component).

In order to address the primary objective (namely, to estimate the rate of stent malpositioning), 97 evaluable subjects are required to achieve a precision (half-width of the 95% confidence interval) of +/-10% (assuming a conservative 50% rate of correct positioning). As assessments are conducted immediately after the procedure, the investigators do not anticipate a significant number of non-evaluable subjects. The proposal is to enrol N=100 subjects in the FB group, with 50 subjects in the retrospective phase and another 50 in the prospective phase. In order to address the secondary objective of comparing malpositioning rates between the two groups (with and without FB), patients in the non-FB group should be enrolled at a 1:2 ratio. The justification for this number is based on feasibility. This will provide preliminary data for the non-FB group. Therefore, given our retrospective cohort of 50 FB subjects with available measurements, the prospective phase will include N=50 + 25-or 75 additional subjects (50 in the FB arm and 25 in the non-FB arm). The analyses will therefore cover a total of 125 subjects (100 with FB and 25 without FB).