The Evolving Role of Drug-Eluting Stents in Peripheral Artery Disease
Peripheral Artery Disease (PAD) represents a significant global health challenge, impacting millions worldwide and serving as a leading cause of cardiovascular morbidity alongside coronary artery disease and stroke [1]. Affecting the arteries outside of the heart and brain, PAD commonly involves the infrainguinal arteries of the lower limbs, leading to symptoms ranging from intermittent claudication to critical limb-threatening ischemia (CLTI), which carries a substantial risk of limb loss [1, 5]. The management of PAD has seen considerable advancements, with endovascular treatment emerging as a cornerstone for revascularization in both femoropopliteal and below-the-knee arterial segments [1]. A key innovation in this field is the development and application of drug-eluting stents (DES), designed to mitigate restenosis—the re-narrowing of the artery—a common complication following angioplasty and bare-metal stenting.
Mechanism of Action and Evolution of Drug-Eluting Stents
Drug-eluting stents are sophisticated devices comprising a stent platform, an antiproliferative drug (such as paclitaxel or limus-based variants), and often a polymer that controls the drug's release kinetics [1]. The stent platform provides mechanical support, preventing vessel recoil and fibrous constrictive remodeling after angioplasty. The embedded drug targets intimal hyperplasia, a biological process involving the migration and proliferation of smooth muscle cells and the accumulation of extracellular matrix, which is the primary cause of restenosis [1].
The effectiveness of DES hinges on the sustained release of the drug to match the kinetics of restenosis, which typically occurs within a year following nitinol stenting in the femoropopliteal segment [1]. Early DES designs primarily utilized paclitaxel, an antineoplastic agent that inhibits cell proliferation. More recently, second-generation limus-eluting stents, such as those loaded with amphilimus formulation, have shown promising results [1]. The choice of drug, the presence and type of polymer, and the release profile are critical factors influencing the long-term efficacy of these devices.
Clinical Evidence and Efficacy in Femoropopliteal Arteries
Numerous clinical trials have investigated the efficacy of DES in treating PAD, particularly in the femoropopliteal arteries. Studies comparing drug-eluting balloons (DCBs) and DES to percutaneous transluminal angioplasty (PTA) alone or with bare-metal stenting (BMS) have consistently demonstrated superior outcomes with drug-eluting technologies [2, 4].
For instance, trials like IN.PACT SFA, LEVANT II, and ILLUMENATE, though primarily focusing on DCBs, highlighted significant improvements in primary patency rates and reductions in clinically driven target lesion revascularization (CD-TLR) compared to PTA [2]. While these trials focused on DCBs, the underlying principle of drug delivery to prevent restenosis is shared with DES. Real-world analyses have further supported these findings, with DES demonstrating higher rates of primary patency and freedom from major adverse limb events (MALE) [4]. One study reported 3-year primary patency rates of 65% for DCB/DES compared to 54% for PTA/S, and 3-year freedom from MALE rates of 84% versus 75%, respectively [4].
Role in Below-the-Knee (BTK) Peripheral Artery Disease
The application of DES in below-the-knee (BTK) PAD presents unique challenges due to the smaller vessel size and complex anatomy. However, emerging evidence suggests a beneficial role for DES in this challenging patient population. A systematic review and meta-analysis indicated that DES, irrespective of the drug type, provided protection against minor amputations and CD-TLR in BTK lesions [5]. Specifically, pooled analysis showed a significant reduction in minor amputations (Odds Ratio [OR] = 0.56) and CD-TLR (OR = 0.38) with DES use [5]. While paclitaxel-eluting stents did not show a significant impact on overall survival or major amputations in this context, everolimus/sirolimus-eluting stents were associated with reduced CD-TLR [5]. This suggests that DES can improve limb salvage and reduce the need for repeat interventions in BTK PAD, although further robust randomized controlled trials are warranted to solidify these findings.
Safety Considerations and Regulatory Landscape
Initially, concerns were raised regarding the safety of paclitaxel-coated devices, particularly a potential late mortality risk identified in a 2018 meta-analysis [3]. This led to a period of heightened scrutiny and recommendations from regulatory bodies like the FDA [3]. However, subsequent comprehensive analyses, including updated meta-analyses with longer-term follow-up data and real-world studies (e.g., SWEDEPAD, VOYAGER PAD, German BARMER Health Insurance study, U.S. Veterans Health Administration study, and Medicare SAFE-PAD study), have largely alleviated these concerns [3]. The FDA, in its updated guidance, concluded that the totality of available data does not support an excess mortality risk for paclitaxel-coated devices [3]. This reassessment has reinforced the acceptable safety profile of these devices, allowing clinicians to utilize them with greater confidence while emphasizing the importance of optimal medical therapy and patient monitoring [3].
Conclusion
Drug-eluting stents have significantly advanced the treatment landscape for peripheral artery disease by offering a means to reduce restenosis and improve long-term patency rates. Evidence from numerous clinical trials and real-world data supports their efficacy in femoropopliteal arteries, leading to improved primary patency and reduced need for repeat revascularization. Furthermore, DES show promise in the challenging below-the-knee segment, contributing to a reduction in minor amputations and CD-TLR. While initial safety concerns regarding paclitaxel-coated devices have been largely addressed through rigorous re-evaluation, ongoing patient monitoring and adherence to optimal medical therapy remain paramount. The evolving role of DES continues to underscore their importance as a valuable tool in the comprehensive management of PAD, aiming to preserve limbs and improve the quality of life for affected individuals.
References
[1] [Drug-eluting devices for lower limb peripheral arterial disease | EuroIntervention](https://eurointervention.pcronline.com/article/drug-eluting-devices-for-lower-limb-peripheral-arterial-disease) [2] [Drug-Eluting Balloons and Drug-Eluting Stents in the Treatment of Peripheral Vascular Disease - PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363541/) [3] [Paclitaxel-Coated Balloons and Stents for Peripheral Arterial Disease | FDA](https://www.fda.gov/medical-devices/cardiovascular-devices/paclitaxel-coated-balloons-and-stents-peripheral-arterial-disease) [4] [Outcomes following drug-coated balloons and drug-eluting stents in patients with peripheral arterial disease](https://www.jvascsurg.org/article/S0741-5214(25)00908-5/abstract) [5] [Drug Eluting Stents as a Management for Patients with Below the Knee Peripheral Artery Disease: A Systematic Review and Meta-Analysis](https://journals.sagepub.com/doi/10.1177/15385744251358129)