Influence of different postballoon expansion procedures: A finite element analysis

Postballoon expansion is considered as an appropriate procedure for adequate stent expansion for coronary bifurcation lesions. Two postballoon expansion procedures are currently recommended: proximal optimization technique (POT)/side/POT and POT/kiss/POT. However, the effects of the two postballoon expansion treatments are different. There is a lack of biomechanical study to quantify the difference.

It is recognized that biomechanical factors influence the occurrence of Major Cardiovascular Adverse Events (MACE), which includes recurrent angina pectoris, acute myocardial infarction and coronary heart disease death. The current paper evaluated the two postexpansion strategies and quantified biomechanical parameters to provide a basis for clinical decisions.

Based on the CT angiography (CTA) data of a patient diagnosed with coronary bifurcation lesions, a personalized coronary bifurcation lesion model was constructed, and the surgical procedure after two expansions was simulated. The POT/side/POT and POT/kiss/POT expansion procedures were analyzed from the perspective of biomechanics through finite element analysis. The biomechanics factors, including the percentage of stent malapposition and stent occlusion at the side branch (SB) opening, the stent ellipse index of proximal main vessel (PMV) segment, the minimum lumen area of the stent vessel segment and the stress distribution of the vessel wall, were used to quantify clinician concerns about factors affecting patient outcomes. The factors include stent adhesion, SB open stent occlusion, poor stent deformation, patency effect of vessel stenosis, and vessel wall damage.

Both postexpansion procedures were successfully simulated. The malapposition rate during POT/side/POT was larger (1.2% vs. 0.42%) and stent occlusion at the SB opening from the cross-section perpendicular to the SB opening after the POT/side/POT procedure was 0.20%, compared with 0.00% after POT/kiss/POT. POT/kiss/POT produced a larger PMV segment stent ellipse index. Minimum lumen area after POT/side/POT was 5.6 mm² and after POT/kiss/POT 5.9 mm² . POT/kiss/POT produces an effect of greater vascular stress than POT/side/POT.

Numerical simulations provide a quantitative analysis to inform clinicians of the differences between preoperative planning and surgical procedures. Biomechanical analysis of the differences between the two postexpansion strategies found that the POT/kiss/POT procedure resulted in better stent fit, less occlusion of the SB open stent and better vascular patency but also resulted in poor stent deformation and caused greater vessel wall stress. The current study informs rationales for clinical understanding of postexpansion strategies.