Arriving with much fanfare to the interventional cardiology scene twenty-plus years ago, Drug-eluting stents (DES) were highly anticipated based on multiple well-performed clinical trials demonstrating substantially improved outcomes in percutaneous coronary intervention (PCI) by lowering rates of restenosis and repeat revascularization while maintaining a strong safety profile. ,, Despite these advances, permanent metallic caging remains an inherent limitation of contemporary DES. Long-term vessel constrainment may impair vasomotion, alter vascular biomechanics, lead to tissue ingrowth and atherosclerosis progression that contribute to late adverse events which continue to accrue over time. ,
The DynamX sirolimus-eluting bioadaptor was designed with this issue in mind. Its central premise is mechanical adaptability—providing early scaffolding and drug delivery, followed by polymer resorption and “uncaging” that allows the vessel to regain more natural motion while leaving behind three helical chromium cobalt strands. This biopolymer resorption results in axial separation of the metallic strands, which in theory, creates dynamic flexibility and a biologically healthier stented segment over time. In a recent issue of The American Journal of Cardiology , Leone et al. report results of the DYNAMITE study, a single-center observational study evaluating the validity of this approach in a setting where it arguably matters most: complex coronary lesions. Unlike earlier studies with this device, which primarily enrolled less challenging anatomy, this investigation intentionally included patients with B2/C lesions, long segments, chronic total occlusions, bifurcations, and significant calcification, strengthening our understanding of this novel device. However, the true novelty and importance of this study relate to the incorporation of serial optical coherence tomography (OCT), which provides high-resolution (<20 um) intraluminal assessment, capturing device expansion, lumen area, tissue growth, and malapposition.
With OCT core lab imaging analyses, the authors report a postprocedure in-device lumen area of 8.27 ± 1.78 mm 2, which is larger than the mean device area of 8.15 ± 0.64mm 2. This would traditionally be interpreted as representing significant device malapposition. However, at 9-month follow-up, the mean device area increased to 8.53 ± 1.71 mm 2 (approximately 5% on average), while the mean in-device lumen area decreased to 7.57 ± 1.86mm 2 (approximately 8%). This, according to the authors, represents ‘positive vessel remodeling’, but is perhaps better described as ‘adaptive remodeling’, where there is ‘controlled’ neointimal proliferation along with concomitant outward vessel adaptation related to an increase in device area. This, they believe, represents an adaptive vascular response that limits the consequences of neointimal hyperplasia, a series of events not possible with the use of traditional DES.
This small study should lead us to reconsider our understanding of device malapposition. It has long been understood that incomplete vessel conformity may create an unfavorable microenvironment that affects healing and long-term stability. Optical Coherence Tomography (OCT) has been demonstrated to detect stent malapposition with greater accuracy, and a higher frequency than angiography or Intravascular Ultrasound. Prior OCT studies identified acute stent malapposition in 5.2% of struts and 62% to 84% of lesions, associated with calcification, severe stenoses and longer stent lengths. On follow up OCT imaging at 6 months, acute stent malapposition mostly resolved (69%), but 16% of lesions were noted to develop late-acquired stent malapposition. , While some studies have demonstrated an association between stent malapposition and adverse clinical events, others have shown no such association. ,,,,
The present study’s duration and structured follow-up provide additional insight. Paired 9-month OCT imaging, combined with 24-month clinical evaluation, allowed detailed observation of how the DynamX bioadaptor integrates into the lumen wall over time. Progressive reduction in malapposition and controlled neointimal growth suggest meaningful stent–vessel interaction rather than passive accommodation. In summary, these meticulous core lab imaging data underscore the value of OCT in our understanding device performance to allow for engineering better outcomes in complex PCI.
We can not however overlook the important limitations of this study. This was a small, single-center, nonrandomized study without a comparator arm. Its findings are not broadly generalizable and cannot allow a comparison to contemporary DES. However, the DYNAMITE study appears intended less as a definitive outcomes trial and more as a proof-of-concept extension study demonstrating consistent performance in anatomically complex disease. Larger, multicenter randomized investigations are needed to determine whether the proposed advantages observed with this novel device translate into any durable clinical benefit. As this platform is designed to modify the intraluminal environment over time, future studies should continue to incorporate high-resolution intravascular imaging—particularly OCT—as a primary modality to assess dynamic changes in device area, lumen dimensions, tissue response, and device–vessel integration.
CRediT authorship contribution statement
Sean Callahan: Writing– original draft, Writing– review & editing. John J. Lopez: Writing– original draft, Writing– review & editing.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
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