What is the difference between bare metal stents (BMS) and drug-eluting stents (DES)?

From the Guidelines

Bare metal stents and drug-eluting stents differ significantly in their design, function, and clinical outcomes, with drug-eluting stents being the preferred choice for most patients due to their lower restenosis rates and superior outcomes in preventing repeat procedures, as supported by the 2011 ACCF/AHA/SCAI guideline for percutaneous coronary intervention 1. The main difference between bare metal stents and drug-eluting stents lies in their ability to prevent restenosis, with drug-eluting stents having a significantly lower restenosis rate compared to bare metal stents, typically 5-10% versus 20-30% 1.

Key Differences

• Bare metal stents are simple mesh-like metal scaffolds that physically hold open narrowed arteries after angioplasty.
• Drug-eluting stents have a similar metal framework but are coated with medications (such as sirolimus, everolimus, zotarolimus, or paclitaxel) that are slowly released into the arterial wall, inhibiting cell proliferation and reducing the risk of restenosis.
• Drug-eluting stents require longer dual antiplatelet therapy (usually aspirin plus a P2Y12 inhibitor like clopidogrel) for at least 6-12 months, while bare metal stents typically require only 1 month of dual therapy 1.

Clinical Outcomes

• Drug-eluting stents have been shown to be associated with a reduced need for repeat revascularization and no increase in death or MI compared with bare metal stents at 4 years’ follow-up 1.
• The risk of stent thrombosis is higher in populations or lesion types excluded from RCTs of DES (e.g., STEMI, smaller arteries [2.5 mm diameter], longer lesions, bifurcations) 1.
• The greatest risk of stent thrombosis is within the first year, ranging from 0.7% to 2.0%, depending on patient and lesion complexity, with late stent thrombosis risk after 1 year with DES observed at a rate of 0.2% to 0.4% per year 1.

Recommendations

• Drug-eluting stents are generally the standard choice for most patients due to their superior outcomes in preventing repeat procedures, despite their higher cost 1.
• Bare metal stents may be preferred for patients who cannot tolerate long-term antiplatelet therapy or who need upcoming surgeries 1.
• The decision to use a drug-eluting stent or a bare metal stent should be based on individual patient characteristics, including the risk of restenosis, the ability to tolerate and comply with dual antiplatelet therapy, and the presence of any medical issues that may increase the risk of bleeding or require invasive or surgical procedures in the following year 1.

From the Research

Difference between Bare Metal Stents and Drug Eluding Stents

• Bare metal stents (BMS) are made of metal and do not release any medication, whereas drug-eluting stents (DES) release medication to prevent cell proliferation and reduce the risk of restenosis 2, 3.
• DES have been shown to reduce the risk of restenosis compared to BMS, but there have been concerns about an increased risk of stent thrombosis 2, 3.
• Newer generation DES, such as everolimus-eluting stents, have been shown to be safe and effective, with reduced risk of stent thrombosis compared to BMS 3, 4.
• Studies have compared the outcomes of PCI with BMS and DES, including rates of death, myocardial infarction, repeat revascularization, and stent thrombosis 5, 4, 6.
• A systematic review and meta-analysis found that second-generation DES had a significantly lower rate of all-cause mortality, target lesion revascularization, and myocardial infarction compared to BMS in large coronary artery PCI 6.

Key Findings

• DES have been shown to be more effective than BMS in preventing restenosis and reducing the risk of repeat revascularization 2, 3, 5, 4, 6.
• Newer generation DES have improved safety and efficacy profiles compared to older generation DES and BMS 3, 4, 6.
• The choice of stent type depends on various factors, including patient characteristics, lesion complexity, and clinical presentation 2, 3, 5, 4, 6.

Stent Thrombosis and Restenosis

• Stent thrombosis is a rare but potentially life-threatening complication of PCI, and the risk is higher with BMS compared to DES 2, 3, 4.
• Restenosis is a common complication of PCI, and DES have been shown to reduce the risk of restenosis compared to BMS 2, 3, 5, 4, 6.
• The risk of restenosis and stent thrombosis can be minimized with optimal stent deployment, adequate antiplatelet therapy, and careful patient selection 2, 3, 5, 4, 6.