Expansion of the Multi-Link Frontier™ Coronary Bifurcation Stent: Micro-Computed Tomographic Assessment in Human Autopsy and Porcine Heart Samples

BACKGROUND: Treatment of coronary bifurcation lesions remains challenging, beyond the introduction of drug eluting stents. Dedicated stent systems are available to improve the technical approach to the treatment of these lesions. However dedicated stent systems have so far not reduced the incidence of stent restenosis. The aim of this study was to assess the expansion of the Multi-Link (ML) Frontier™ stent in human and porcine coronary arteries to provide the cardiologist with useful in-vitro information for stent implantation and selection. METHODOLOGY/PRINCIPAL FINDINGS: Nine ML Frontier™ stents were implanted in seven human autopsy heart samples with known coronary artery disease and five ML Frontier™ stents were implanted in five porcine hearts. Proximal, distal and side branch diameters (PD, DD, SBD, respectively), corresponding opening areas (PA, DA, SBA) and the mean stent length (L) were assessed by micro-computed tomography (micro-CT). PD and PA were significantly smaller in human autopsy heart samples than in porcine heart samples (3.54±0.47 mm vs. 4.04±0.22 mm, p = 0.048; 10.00±2.42 mm(2) vs. 12.84±1.38 mm(2), p = 0.034, respectively) and than those given by the manufacturer (3.54±0.47 mm vs. 4.03 mm, p = 0.014). L was smaller in human autopsy heart samples than in porcine heart samples, although data did not reach significance (16.66±1.30 mm vs. 17.30±0.51 mm, p = 0.32), and significantly smaller than that given by the manufacturer (16.66±1.30 mm vs. 18 mm, p = 0.015). CONCLUSIONS/SIGNIFICANCE: Micro-CT is a feasible tool for exact surveying of dedicated stent systems and could make a contribution to the development of these devices. The proximal diameter and proximal area of the stent system were considerably smaller in human autopsy heart samples than in porcine heart samples and than those given by the manufacturer. Special consideration should be given to the stent deployment procedure (and to the follow-up) of dedicated stent systems, considering final intravascular ultrasound or optical coherence tomography to visualize (and if necessary optimize) stent expansion

Comparison of stent dimensions between autopsy hearts, porcine model and data given by the manufacturer.

<p>Proximal stent diameters (PD) were significantly smaller in human autopsy heart samples than in porcine heart samples (P = 0.048) and than those given by the manufacturer (P = 0.014). The mean stent length was smaller in human autopsy hearts than in porcine heart samples (P = 0.32), and also significantly smaller than that given by the manufacturer (P = 0.015). Side branch diameters (SBD) and distal stent diameters (DD) did not differ significantly.</p

Micro-CT analysis of stent diameters, opening areas and stent length.

<p>n = Location of bifurcation:</p>1<p>left anterior descending (LAD)/ramus diagonalis (RD) I,</p>2<p>LAD/RD II,</p>3<p>LAD/left circumflex,</p>4<p>right coronary artery: ramus interventricularis posterior/ramus posterolateralis dexter.</p>*<p>Measured before stent implantation by QCA.</p>†<p>Calculated with stent diameter given by manufacturer.</p>‡<p>Calculated with stent diameter assessed by Micro-CT.</p>**<p>Opening area was calculated using the circle formula area = π radius². RLD: reference luminal diameter; QCA: quantitative coronary angiography.</p

Assessment of the stent length.

<p>2D measurement (panel A) and 3D visualization (panel B) of stent length by micro-CT.</p