What Have We Learned From Explanted Peripheral Stents Analysis?

Introduction: The behavior of endovascular devices used to treat peripheral artery obstructive disease (PAOD) is evaluated on in vitro and in vivo animal models that do not necessarily predict their behavior in humans. Direct in vivo analysis is not feasible; therefore, studying explanted stents might help the approach understand their in vivo behavior and their potential long-term complications. Consequently, studying their in vivo behavior in human diseased vessels is necessary to improve them. This study aims to summarize current knowledge on the analysis of peripheral stents explanted in humans suffering from PAOD.

Methods: A descriptive review of the MEDLINE and EMBASE databases was performed by a combined strategy of MeSH terms: "peripheral stenting," "histology," "stents," "pathology," "neoatherosclerosis," and "explants"; with no time limit.

Results: The literature search identified 18 publications; 4 addressed both femoral and iliac stents, 9 addressed exclusively femoral explanted stents, and 5 addressed carotid explanted stents. No reports addressing subclavian, vertebral, or renal stents were found. The total number of cases reported was 42, with 46 stented lesions including 58 devices. Twenty-seven femoral stented lesions were analyzed, and out of them, 20 presented with failure (74.1%). Eleven iliac stented lesions were analyzed; out of them, 9 (82%) had restenosis, and all of them presented with delayed healing. Eight carotid stented lesions were analyzed, of which 4 (50%) presented failures. Stent failures in iliac arteries were due to delayed healing, in femoral arteries due to intimal calcifications and stent integrity, and in carotid arteries due to underlying lipid-rich necrotic core causing ulceration; delayed healing (bare struts) was a common reason for stent failure in every type of peripheral bed.

Conclusion: Our review showed that we have minimal data on the actual behavior of stents in humans, although it is fundamental to understand their performance. Failed peripheral stent explants are associated with delayed healing, and plaque-type morphology is linked to stent outcome. It is essential for peripheral stent explants to be analyzed in larger numbers to gather more pathologic data to make meaningful improvements.Clinical ImpactThis review identified only 18 publications addressing peripheral stent explant analysis, demonstrating that stent healing and failures are different within peripheral beds. This review highlights the need for a greater understanding of peripheral stenting pathology, and the only way we can do that is by analyzing a greater number of stent explants. It brings to light the fact, that we need to characterize each plaque to choose the appropriate endovascular treatment.