Drug-Eluting Stents and Local DrugDelivery for the Prevention ofRestenosis Flashcards
What is the main effect of antiproliferative drugs?
Inhibition of smooth muscle cell proliferation and migration by interfering with the cell cycle
This effect is crucial for preventing restenosis after vascular interventions.
How does the radial force of a stent affect the vessel?
It inhibits potential elastic recoil of the vessel
This helps maintain the vessel’s patency after stent placement.
What side effect may be induced by the implantation of a drug-eluting stent (DES)?
Positive arterial remodeling resulting in late malapposition of the stent
This can complicate the long-term outcomes of stent implantation.
What is Everolimus primarily developed as?
An immunosuppressant inhibiting the expression of hypoxia-inducible factor (HIF-1)
It is used in the prevention of coronary restenosis.
What does Everolimus inhibit in cell proliferation?
mTOR kinase activity
This leads to reduced activity of downstream effectors like S6K1 and 4EBP.
What is the mechanism of action of Paclitaxel?
Promotes the polymerization of tubulin
Unlike other antimicrotubule agents, it does not induce disassembly of microtubules.
What are the two nonerodable polymers used in the Cypher stent for drug release?
- Polyethylene-co-vinyl acetate (PEVA)
- Poly n-butyl methacrylate (PBMA)
These polymers control the release of the drug from the stent.
What is a polymer?
A high molecular weight organic compound consisting of many repeating simpler chemical units called monomers
Examples include proteins (polymers of amino acids) and cellulose (polymers of sugar molecules).
What does the late loss refer to in stent studies?
Minimal lumen diameter at follow-up minus the postprocedural minimal lumen diameter at baseline
A late loss of 0.5 to 0.6 typically triggers a target lesion revascularization (TLR).
What is the risk factor for late stent thrombosis?
- Hypersensitivity to drug coating and polymer
- Incomplete endothelialization
- Procedural factors like inadequate stent expansion and apposition
- Patient factors such as diabetes and long lesions
The rate of late stent thrombosis is <1% per year with first-generation DES.
True or False: The Cypher stent is composed of a biodegradable polymer.
False
The Cypher stent is made of stainless steel and uses non-biodegradable polymers.
What does the SIRTAX trial demonstrate regarding sirolimus?
Fewer major adverse cardiac events (MACE) primarily by decreasing rates of clinical and angiographic restenosis
This highlights the efficacy of sirolimus in stent therapy.
What is the primary endpoint in the SIRTAX trial?
Composite of cardiac death, myocardial infarction, and target lesion revascularization
This endpoint assesses the overall effectiveness of the stent treatment.
What is the significance of complete re-endothelialization after BMS implantation?
Usually achieved within 1 month
However, the healing process is prolonged after DES implantation.
What is the primary advantage of bioresorbable stents?
They leave nothing behind as the polymer degrades and is absorbed by the body
This theoretically facilitates re-endothelialization and reduces neoatherosclerosis.
What is the most frequently used polymer for bioresorbable stents?
- PLLA
- Poly(glycolic acid) (PGA)
- Poly(e-caprolactone) (PCL)
These polymers are favored for their biocompatibility and absorption properties.
What were the findings of the PLATINUM trial regarding stent types?
Similar rates of target lesion failure, stent thrombosis, all-cause mortality, and MI between the two stent groups
This trial led to the approval of the PROMUS Element stent.
How does DES implantation affect exercise-induced coronary vasoconstriction?
SES or PES is associated with exercise-induced paradoxic coronary vasoconstriction of adjacent vessel segments
However, the vasodilatory response to nitroglycerin is maintained.
What are the outcomes of the EVOLVE II trial?
Rates of definite and probably stent thrombosis were low in both SYNERGY and PROMUS groups
This indicates the safety of both stent types with <1% stent thrombosis.
Fill in the blank: The OCT images show a _______ stent, which is a known risk factor for stent thrombosis.
malapposed
Proper apposition of the stent is crucial to prevent thrombosis.
What does BVS stand for?
Bioabsorbable Vascular Scaffold
BVS is a type of stent designed to dissolve after serving its purpose.
Which BVS is currently FDA-approved?
ABSORB
ABSORB is the only BVS that has received FDA approval.
What were the trials that studied the ABSORB stent?
ABORB I, II, and III
These trials evaluated the performance and safety of the ABSORB stent.
What was the primary comparison in the ABSORB trials?
Compared to the second-generation stent XIENCE
The trials aimed to determine noninferiority against the XIENCE stent.
What was the outcome regarding noninferiority for the ABSORB stent?
Met its noninferiority endpoints
This result contributed to its FDA approval.
What concern was raised by several meta-analyses regarding the ABSORB stent?
Higher stent thrombosis rates
This concern highlighted potential safety issues with the ABSORB stent.
What were the stent thrombosis rates in the AIDA study for the ABSORB group?
3.5%
This rate was significantly higher compared to 0.9% in the control group (p < 0.001).
Did target lesion failure, cardiac death, and TLR differ between the ABSORB group and control?
No, rates did not differ
These outcomes were statistically similar between the groups.
What is the status of long-term data for the ABSORB stent beyond 2 years?
Pending
Long-term outcomes are still being investigated.
What are newer generation BVS currently undergoing?
Investigations
These studies may address limitations of current generation BVS platforms.
