Revolutionary Esprit BTK Scaffold Shows Promise in Treating Chronic Limb-Threatening Ischemia

Can the Esprit BTK Scaffold Redefine BTK Interventions in CLTI?

The LIFE-BTK trial has demonstrated significant long-term benefits of a novel everolimus-eluting resorbable scaffold in patients with chronic limb-threatening ischemia (CLTI), according to recently published two-year results. The Esprit BTK drug-eluting resorbable scaffold (DRS) showed sustained superiority over percutaneous transluminal angioplasty (PTA) in maintaining vessel patency and reducing the need for reinterventions in patients with below-the-knee (BTK) arterial disease.

CLTI represents an advanced stage of peripheral arterial disease characterized by impaired perfusion of the lower extremities, manifesting as ischemic rest pain, nonhealing wounds, or gangrene. Historically, surgical bypass has been the gold standard for revascularization, but endovascular approaches have gained prominence in recent decades as less invasive alternatives. However, the high prevalence of infrapopliteal disease in CLTI patients presents unique challenges, with conventional PTA showing disappointing long-term outcomes due to high rates of restenosis and reintervention. The LIFE-BTK trial was designed to address these limitations by evaluating a novel bioresorbable scaffold that combines mechanical support with antiproliferative drug delivery.

How Was the LIFE-BTK Trial Designed and Who Were the Participants?

The multicenter, subject-blinded randomized controlled trial enrolled 261 patients with CLTI across 50 sites in six countries between July 2020 and September 2022. Participants had Rutherford-Becker class 4 (ischemic rest pain) or 5 (minor tissue loss) disease with significant infrapopliteal artery stenosis or occlusion. The study population had a mean age of 72.6 years, with 32% women and diverse racial backgrounds (59% White, 18% Asian, and 12% Black). Notably, 93% had hypertension, 81% had dyslipidemia, and 71% had diabetes, reflecting the complex comorbidity profile typical of CLTI patients. Participants were randomized in a 2:1 ratio to receive either the Esprit BTK DRS (n=173) or standard PTA (n=88).

The Esprit BTK DRS consists of a poly(L-lactide) backbone coated with everolimus and poly(D,L-lactide), designed to provide temporary mechanical support while delivering antiproliferative therapy during the critical restenotic phase. Unlike permanent metal stents, the scaffold fully resorbs over time, allowing for vessel restoration and future interventional options. The trial protocol mandated predilatation before scaffold placement, with recommended postdilatation using appropriately sized noncompliant balloons. Dual antiplatelet therapy (DAPT) was recommended for at least one year in the DRS group compared to one month in the PTA group, though interestingly, more PTA patients remained on DAPT at the two-year follow-up (76.7% versus 66.1%).

Do Efficacy and Safety Endpoints Favor the DRS Over PTA?

The primary efficacy endpoint was a composite of primary patency and limb salvage, defined as freedom from target limb amputation above the ankle, total occlusion of the target vessel, clinically driven target lesion revascularization (CD-TLR), or binary restenosis of the target lesion. At two years, this endpoint was achieved in 61.5% of patients in the DRS group compared to just 32.8% in the PTA group, representing an absolute risk difference of 28.7% and a hazard ratio of 0.48 (p=0.0004). This substantial benefit was consistent across the individual components of the composite endpoint, with the DRS group showing higher freedom from binary restenosis (64.8% versus 42.2%) and CD-TLR (88.5% versus 76.6%). Freedom from above-ankle amputation remained high in both groups (93.4% for DRS versus 96.9% for PTA).

The primary safety endpoint, freedom from major adverse limb events at two years and perioperative death at 30 days, was observed in 91.6% of patients in the DRS group compared with 95.6% in the PTA group (HR 2.39, 95% CI 0.68-8.38; p=0.16), indicating no significant safety concerns with the novel device. The Kaplan-Meier analysis of binary restenosis showed that the separation between treatment groups became evident early and was maintained throughout the follow-up period, with restenosis rates of 28.5% in the DRS group and 48.2% in the PTA group at two years (HR 1.85, p=0.005). Similarly, CD-TLR rates were significantly lower in the DRS group (9.7% versus 18.6%; HR 2.15, p=0.034).

Which Predictive Factors Shape the Outcomes?

Predictive factor analysis identified several variables associated with outcomes. Treatment with DRS was consistently associated with lower odds of primary endpoint failure (odds ratio 0.31, p=0.0003) and showed a trend toward reduced CD-TLR (OR 0.46, p=0.054). Other significant predictors of adverse outcomes included longer lesion length, total occlusion at the treatment site, Rutherford-Becker class 5, previous amputation, and higher wound burden at baseline. Subgroup analyses demonstrated that the benefit of DRS was consistent across most patient populations, including those with and without diabetes, varying levels of calcification, and different lesion lengths. A significant interaction was observed for CD-TLR based on inflow lesion treatment (p=0.037), with DRS showing particularly strong benefits in patients without inflow lesion treatment.

Could These Results Reshape Endovascular Strategies for CLTI?

The LIFE-BTK trial results have important implications for the management of BTK disease in CLTI patients. The sustained efficacy of the Esprit BTK DRS over two years addresses a critical need for durable solutions in this challenging patient population. The device's ability to maintain vessel patency while avoiding the limitations of permanent metal implants represents a significant advance in endovascular therapy. By reducing the need for reinterventions, the DRS may improve quality of life for patients while potentially reducing healthcare resource utilization associated with repeat procedures. The consistent benefit across diverse patient subgroups suggests broad applicability in clinical practice, though the trial's focus on relatively simple lesions (80% TASC II A/B) may limit generalizability to more complex anatomies.

Could these findings shift the paradigm for BTK interventions in CLTI patients? The results certainly challenge the status quo of PTA as the default endovascular strategy. While surgical bypass with autologous conduit remains the gold standard for suitable candidates, as reinforced by the BEST-CLI trial, many patients with CLTI are poor surgical candidates due to comorbidities or lack of adequate vein conduits. For these patients, the Esprit BTK DRS offers a promising alternative that addresses both the mechanical and biological factors contributing to restenosis. How might the implementation of this technology impact the broader spectrum of CLTI care, including wound healing protocols, surveillance strategies, and the timing of interventions? These questions warrant further investigation in real-world settings and future clinical trials.

What Does the Future Hold for BTK Interventions in CLTI?

What remains to be determined is how the Esprit BTK DRS compares to other emerging technologies for BTK disease, such as drug-coated balloons, intravascular lithotripsy for calcified lesions, or newer-generation drug-eluting stents. Additionally, the cost-effectiveness of this approach relative to conventional therapy needs evaluation, particularly considering the potential reduction in reinterventions. As the technology becomes more widely adopted, understanding its performance in more complex, real-world anatomies and higher-risk patients will be crucial for optimizing patient selection and procedural techniques. The ongoing Esprit BTK postapproval study may provide valuable insights into these questions.

In conclusion, the two-year results from the LIFE-BTK trial demonstrate that the Esprit BTK everolimus-eluting resorbable scaffold significantly improves primary patency compared to balloon angioplasty in patients with CLTI. The scaffold reduces rates of binary restenosis and clinically driven target lesion revascularization while maintaining a comparable safety profile. These findings position the Esprit BTK scaffold as a valuable addition to the armamentarium for treating infrapopliteal artery disease in appropriately selected patients with CLTI, potentially changing the landscape of endovascular therapy for this challenging condition.

Summary

The LIFE-BTK trial evaluated the Esprit BTK drug-eluting resorbable scaffold (DRS) against percutaneous transluminal angioplasty (PTA) in treating chronic limb-threatening ischemia. The study involved 261 patients across 50 sites, with two-year results showing significant benefits of the DRS. The primary efficacy endpoint was achieved in 61.5% of DRS patients compared to 32.8% in the PTA group. The scaffold demonstrated superior vessel patency, reduced binary restenosis (64.8% vs 42.2%), and fewer target lesion revascularizations (88.5% vs 76.6%). Safety outcomes were comparable between groups, with no significant concerns. The device's success across diverse patient subgroups and its ability to provide temporary support while delivering antiproliferative therapy positions it as a promising alternative to conventional treatments for below-the-knee arterial disease.