A new study published in EuroIntervention has shown that chimney stenting (ChS)  may lead to significant stent distortion and limit future coronary access (CA), especially in anatomically complex cases.

The study focused on patients who had previously received supra-annular self-expanding transcatheter aortic valves (TAVs), such as ACURATE neo2 (ACn2) or Evolut PRO (EvPRO), and were undergoing a second (redo) TAVI using the balloon-expandable SAPIEN 3 Ultra (S3U). Researchers created 3D-printed models of patient-specific anatomy based on CT scans and simulated TAVI procedures in a lab setup that mimicked heart function.

Chimney stents were placed to protect the coronary arteries during redo-TAVI, and researchers measured the extent to which the stents expanded and whether they maintained their shape. They also assessed the future possibility of coronary interventions, such as percutaneous coronary intervention (PCI), after the procedure.

The results found significant issues. The stents often became underexpanded or distorted due to interactions with the original TAV frames or the aortic wall. The most severe case involved a high-positioned S3U implant inside an EvPRO valve, leading to nearly complete stent crushing and a vertical distortion angle of up to 75°. When the original valve had severe commissural misalignment (CMA), lateral distortion was also severe, up to 53° in some cases. When both severe CMA and a high S3U implant were present, 75% of cases made future coronary access or PCI impossible.