Drug-Eluting Stents and Local DrugDelivery for the Prevention ofRestenosis

Question 1

What is the main effect of antiproliferative drugs?

Answer 1

Inhibition of smooth muscle cell proliferation and migration by interfering with the cell cycle

This effect is crucial for preventing restenosis after vascular interventions.

Question 2

How does the radial force of a stent affect the vessel?

Answer 2

It inhibits potential elastic recoil of the vessel

This helps maintain the vessel’s patency after stent placement.

Question 3

What side effect may be induced by the implantation of a drug-eluting stent (DES)?

Answer 3

Positive arterial remodeling resulting in late malapposition of the stent

This can complicate the long-term outcomes of stent implantation.

Question 4

What is Everolimus primarily developed as?

Answer 4

An immunosuppressant inhibiting the expression of hypoxia-inducible factor (HIF-1)

It is used in the prevention of coronary restenosis.

Question 5

What does Everolimus inhibit in cell proliferation?

Answer 5

mTOR kinase activity

This leads to reduced activity of downstream effectors like S6K1 and 4EBP.

Question 6

What is the mechanism of action of Paclitaxel?

Answer 6

Promotes the polymerization of tubulin

Unlike other antimicrotubule agents, it does not induce disassembly of microtubules.

Question 7

What are the two nonerodable polymers used in the Cypher stent for drug release?

Answer 7

• Polyethylene-co-vinyl acetate (PEVA)
• Poly n-butyl methacrylate (PBMA)

These polymers control the release of the drug from the stent.

Question 8

What is a polymer?

Answer 8

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).

Question 9

What does the late loss refer to in stent studies?

Answer 9

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).

Question 10

What is the risk factor for late stent thrombosis?

Answer 10

• 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.

Question 11

True or False: The Cypher stent is composed of a biodegradable polymer.

Answer 11

False

The Cypher stent is made of stainless steel and uses non-biodegradable polymers.

Question 12

What does the SIRTAX trial demonstrate regarding sirolimus?

Answer 12

Fewer major adverse cardiac events (MACE) primarily by decreasing rates of clinical and angiographic restenosis

This highlights the efficacy of sirolimus in stent therapy.

Question 13

What is the primary endpoint in the SIRTAX trial?

Answer 13

Composite of cardiac death, myocardial infarction, and target lesion revascularization

This endpoint assesses the overall effectiveness of the stent treatment.

Question 14

What is the significance of complete re-endothelialization after BMS implantation?

Answer 14

Usually achieved within 1 month

However, the healing process is prolonged after DES implantation.

Question 15

What is the primary advantage of bioresorbable stents?

Answer 15

They leave nothing behind as the polymer degrades and is absorbed by the body

This theoretically facilitates re-endothelialization and reduces neoatherosclerosis.

Question 16

What is the most frequently used polymer for bioresorbable stents?

Answer 16

• PLLA
• Poly(glycolic acid) (PGA)
• Poly(e-caprolactone) (PCL)

These polymers are favored for their biocompatibility and absorption properties.

Question 17

What were the findings of the PLATINUM trial regarding stent types?

Answer 17

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.

Question 18

How does DES implantation affect exercise-induced coronary vasoconstriction?

Answer 18

SES or PES is associated with exercise-induced paradoxic coronary vasoconstriction of adjacent vessel segments

However, the vasodilatory response to nitroglycerin is maintained.

Question 19

What are the outcomes of the EVOLVE II trial?

Answer 19

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.

Question 20

Fill in the blank: The OCT images show a _______ stent, which is a known risk factor for stent thrombosis.

Answer 20

malapposed

Proper apposition of the stent is crucial to prevent thrombosis.

Question 21

What does BVS stand for?

Answer 21

Bioabsorbable Vascular Scaffold

BVS is a type of stent designed to dissolve after serving its purpose.

Question 22

Which BVS is currently FDA-approved?

Answer 22

ABSORB

ABSORB is the only BVS that has received FDA approval.

Question 23

What were the trials that studied the ABSORB stent?

Answer 23

ABORB I, II, and III

These trials evaluated the performance and safety of the ABSORB stent.

Question 24

What was the primary comparison in the ABSORB trials?

Answer 24

Compared to the second-generation stent XIENCE

The trials aimed to determine noninferiority against the XIENCE stent.

Question 25

What was the outcome regarding noninferiority for the ABSORB stent?

Answer 25

Met its noninferiority endpoints

This result contributed to its FDA approval.

Question 26

What concern was raised by several meta-analyses regarding the ABSORB stent?

Answer 26

Higher stent thrombosis rates

This concern highlighted potential safety issues with the ABSORB stent.

Question 27

What were the stent thrombosis rates in the AIDA study for the ABSORB group?

Answer 27

3.5%

This rate was significantly higher compared to 0.9% in the control group (p < 0.001).

Question 28

Did target lesion failure, cardiac death, and TLR differ between the ABSORB group and control?

Answer 28

No, rates did not differ

These outcomes were statistically similar between the groups.

Question 29

What is the status of long-term data for the ABSORB stent beyond 2 years?

Answer 29

Pending

Long-term outcomes are still being investigated.

Question 30

What are newer generation BVS currently undergoing?

Answer 30

Investigations

These studies may address limitations of current generation BVS platforms.