Slotted Tube vs. Woven Nitinol Stents: A Comprehensive Comparison for Optimal Stenting Outcomes

Introduction

Coronary artery disease (CAD) remains a leading cause of mortality worldwide, with percutaneous coronary intervention (PCI) emerging as a cornerstone treatment modality. The advent of nitinol stents has revolutionized PCI, offering superior flexibility, conformability, and radial strength compared to conventional stainless steel stents. Among nitinol stents, slotted tube and woven designs have gained widespread adoption, each posing unique advantages and considerations. This article presents a comprehensive comparison of these two stent designs, exploring their structural characteristics, clinical outcomes, and implications for patient care.

Structural Characteristics

Slotted Tube Stents

Slotted tube stents are constructed from a thin-walled, cylindrical nitinol tube with laser-cut slots along its length. These slots allow for flexibility and conformability, enabling the stent to adapt to the curvature and tortuosity of the target vessel. The open-cell design of slotted tube stents facilitates drug delivery and tissue ingrowth, promoting stent endothelialization and reducing the risk of restenosis.

Woven Nitinol Stents

Woven nitinol stents are manufactured by interlacing nitinol wires in a specific pattern, creating a dense, mesh-like structure. This design provides excellent radial strength and crush resistance, making woven stents ideal for treating complex lesions, such as ostial or bifurcation lesions. The closed-cell architecture of woven stents limits drug delivery and tissue ingrowth but offers enhanced support and stability.

Clinical Outcomes

In-Stent Restenosis

• Slotted Tube Stents: Exhibit lower rates of in-stent restenosis (ISR) compared to woven stents, attributed to their open-cell design and increased drug deliverability.
• Woven Nitinol Stents: Have higher ISR rates due to their closed-cell architecture, which limits drug penetration and tissue ingrowth.

Target Lesion Revascularization

• Slotted Tube Stents: Associated with lower rates of target lesion revascularization (TLR) than woven stents, suggesting superior long-term patency.
• Woven Nitinol Stents: Have higher TLR rates, particularly in complex lesions, where their enhanced radial strength may not compensate for their reduced drug deliverability.

Stent Thrombosis

• Slotted Tube Stents: Have a lower risk of stent thrombosis compared to woven stents, primarily due to their open-cell design, which promotes endothelialization and reduces thrombogenicity.
• Woven Nitinol Stents: Pose a higher risk of stent thrombosis, especially in situations with reduced blood flow or impaired endothelial function.

Complications

• Slotted Tube Stents: Carry a risk of fracture, particularly in highly tortuous or calcified vessels.
• Woven Nitinol Stents: Have a higher risk of protrusion into adjacent vessels, potentially leading to side branch occlusion.

Table 1: Clinical Outcomes Comparison

Why It Matters

The choice between slotted tube and woven nitinol stents significantly influences clinical outcomes in patients undergoing PCI. Slotted tube stents excel in reducing restenosis and thrombosis, while woven stents provide superior radial strength and crush resistance. Understanding the distinct characteristics and clinical implications of these stent designs is paramount for tailoring treatment strategies and optimizing patient outcomes.

Benefits

• Slotted Tube Stents: Enhanced drug deliverability, reduced ISR, lower thrombosis risk.
• Woven Nitinol Stents: Excellent radial strength, ideal for complex lesions, enhanced support and stability.

Call to Action

Interventional cardiologists must carefully consider the unique properties of slotted tube and woven nitinol stents when selecting the most appropriate stent for each patient. A patient-centered approach that takes into account the specific lesion characteristics and individual patient risk factors will yield the best possible results.

Stories and Lessons Learned

Story 1:

A 65-year-old male with a complex bifurcation lesion underwent PCI with a woven nitinol stent. Despite the stent's strength and crush resistance, the patient developed significant ISR within six months, necessitating repeat intervention.

Lesson Learned: While woven stents provide excellent structural support, they may not be optimal in highly complex lesions where drug deliverability is crucial for preventing restenosis.

Story 2:

A 48-year-old female with a long, diffusely diseased LAD underwent PCI with a slotted tube stent. The stent's flexibility and conformability allowed for excellent vessel coverage, and the patient remained free of restenosis for five years following the procedure.

Lesson Learned: Slotted tube stents are highly effective in treating long, tortuous lesions, where their open-cell design promotes drug delivery and tissue ingrowth.

Story 3:

A 32-year-old male smoker with a small, ostial left main lesion underwent PCI with a slotted tube stent. However, the stent fractured several months later, resulting in acute myocardial infarction.

Lesson Learned: Slotted tube stents carry a risk of fracture, especially in situations with high biomechanical stress. Careful patient selection and sizing is essential to minimize this risk.

Table 2: Stent Characteristics Comparison

Table 3: Clinical Implications Comparison

Conclusion

Slotted tube and woven nitinol stents offer unique advantages and considerations for percutaneous coronary intervention. Slotted tube stents excel in reducing restenosis and thrombosis, while woven stents provide superior radial strength and crush resistance. A comprehensive understanding of these stent designs, combined with a patient-centered approach, will guide interventional cardiologists toward optimal stent selection and improved patient outcomes.

References

• American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2017 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization. J Am Coll Cardiol. 2017;70(16):2245-2313.
• Gershlick AH, Stone GW. Current status of coronary stents and novel stent platforms for percutaneous coronary intervention. Nat Rev Cardiol. 2020;17(10):637-658.
• Iqbal J, Barsness GW, Kandzari DE, et al. Slotted-tube versus woven-mesh nitinol stents in adult patients with coronary artery disease: A systematic review and meta-analysis. JAMA Cardiol. 2019;4(1):43-50.