Coronary artery rotation in native and stented porcine coronary arteries

24-Month Clinical Follow-Up and Mechanistic Insights From Intravascular Imaging Following Coronary Implantation of the Novel DynamX Bioadaptor Platform

BACKGROUND/PURPOSE

Conventional stents "cage" the coronary arteries, impairing vascular function and physiology. The DynamX Bioadaptor is a cobalt‑chromium platform with uncaging elements, designed to improve arterial pulsatility, vasomotion, compliance, and positive adaptive remodelling which may attenuate late clinical events associated with the caging of arteries through conventional stents. We present the first 24-month outcomes of this device.

METHODS/MATERIALS

This European multicenter study enrolled 50 patients with 50 de novo lesions treated with the DynamX Bioadaptor. Clinical follow-up is scheduled until 36 months and imaging follow-up was performed at 9-12 months.

RESULTS

24-month endpoints were target lesion failure (2 cardiac deaths), myocardial infarction (1 non-target vessel myocardial infarction), target vessel revascularisation (n = 0), and definite or probable device thrombosis (n = 0). No endpoint events occurred beyond 9 months. Paired intravascular ultrasound analysis of 18 patients from a single center revealed a 0.22 mm² increase in device cross-sectional area at 9-12 months. Pulsatility analysis showed an increase of in-device lumen area change by 46 % compared to the caged post-procedural configuration, reducing the compliance mismatch between the treated and not-treated vessel segments (segmental compliance). Likewise, vasomotion in response to nitroglycerin improved from 0.03mm² post-procedure to 0.17mm² at follow-up.

CONCLUSIONS

24-month clinical data demonstrate promising safety and efficacy of the DynamX Bioadaptor. Imaging data confirmed its unique capacity to improve arterial pulsatility, vasomotion, compliance and positive adaptive remodelling after "uncaging" which might have led to the promising clinical outcomes that need to be confirmed in larger studies.

Coronary Artery Radial Deformation and Velocity in Native and Stented Arteries

Introduction

Coronary arteries are exposed to a variety of complex biomechanical forces during a normal cardiac cycle. These forces have the potential to contribute to coronary stent failure. Recent advances in stent design allow for the transmission of native pulsatile biomechanical forces in the stented vessel. However, there is a significant lack of evidence in a human model to measure vessel motion in native coronary arteries and stent conformability. Thus, we aimed to characterize and define coronary artery radial deformation and the effect of stent implantation on arterial deformation.

Materials and Methods

Intravascular ultrasound (IVUS) pullback DICOM images were obtained from human coronary arteries using a coronary ultrasound catheter. Using two-dimensional speckle tracking, coronary artery radial deformation was defined as the inward and outward displacement (mm) and velocity (cm/s) of the arterial wall during the cardiac cycle. These deformation values were obtained in native and third-generation drug-eluting stented artery segments.

Results

A total of 20 coronary artery segments were independently analyzed pre and poststent implantation for a total of 40 IVUS runs. Stent implantation impacted the degree of radial deformation and velocity. Mean radial deformation in native coronary arteries was 0.1230 mm ± 0.0522 mm compared to 0.0775 mm ± 0.0376 mm in stented vessels (p=0.0031). Mean radial velocity in native coronary arteries was 0.1194 cm/s ± 0.0535 cm/s compared to 0.0840 cm/s ± 0.0399 cm/s in stented vessels (p=0.0228).

Conclusion

In this in vivo analysis of third-generation stents, stent implantation attenuates normal human coronary deformation during the cardiac cycle. The implications of these findings on stent failure and improved clinical outcomes require further investigation.

Adaptive coronary artery rotational motion through uncaging of a drug-eluting bioadaptor aiming to reduce stress on the coronary artery

BACKGROUND

Caged drug-eluting stents impede natural coronary rotational motion and increase vessel stress, which can contribute towards adverse events. The DynamX™ Drug-Eluting Bioadaptor is a cobalt‑chromium platform with a novel mechanism that uncages the vessel after the bioresorbable coating resorbs over six months. This study aimed to analyze the effects of the rotational uncaging in a finite element analysis (FEA) model, validating its effect on coronary artery rotational motion through in-vivo stationary intravascular ultrasound (IVUS).

METHODS

Maximum Von Mises stresses were measured in an FEA model and compared for caged and uncaged bioadaptors. Stationary IVUS images from 20 patients enrolled in a single center were acquired post implantation and at 9-12-month follow-up to evaluate coronary artery rotational motion.

RESULTS

The FEA model showed that rotational uncaging of the bioadaptor reduces peak stress by 70%. In-vivo, the in-bioadaptor segment was significantly distorted post-implant compared to the native distal and proximal vessel, measured by IVUS: The sum of clockwise and counterclockwise rotational motion (net-effect rotational motion) was -2.7 ± 4.3° versus 0.5 ± 5.0° (proximal vessel), p = 0.036, and versus 0.2 ± 3.8° (distal vessel), p = 0.042. At follow up, when the bioadaptor had uncaged, the vessel returned towards its equilibrium (net-effect rotational motion -0.2 ± 5.6°), with no significant difference between the vessel segments.

CONCLUSIONS

In concurrence with the FEA observation, the in-vivo IVUS-analysis demonstrates that uncaging of the bioadaptor affects coronary artery rotational motion. The effect of these findings on reducing clinical events warrants further investigation.