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Introduction
Definition of Polymer-Free Drug-Eluting Stents
Polymer - free drug - eluting stents ( PF - DES ) are a type of coronary stent that delivers a drug that will prevent the occurrent of restenosis , or the re - narrowing of the blood vessel , without using a polymer coating . alternatively , the drug is directly coated onto the stent surface or incorporated into the stent cloth itself . This glide slope eliminates the need for a polymer covering , which may cause kindling or hold up healing in some patients.(1 )
Polymer - free drug - elute stent have issue as an alternative to traditional drug - eluting stents ( DES ) for the treatment of coronary artery disease . The use of PF - DES aims to reduce the risk of inflammation and delay healing associate with the polymer coatings used in traditional DES.(2 )
PF - DES have demonstrate a mint of promise in reduce the risk of exposure of restenosis and other adverse events as compare to spare - metal stents . However , further research is still needed to completely understand and evaluate their safety and efficacy .
Historical Background And Evolution Of Coronary Stents
The use of coronary stents to treatcoronary artery diseasebegan in the late 1980s as a new proficiency to ameliorate the resultant of transcutaneous coronary interventions ( PCI ) . The first stent was a bare - alloy stent ( BMS ) made out of unsullied brand . The use of BMS rapidly spread out throughout the world because of to its potency in reducing the risk of restenosis compared to balloonangioplastyalone.(3,4 )
However , BMS also had limitations , include a high risk of in - stent restenosis make by neo - intimal hyperplasia , which circumscribe the long - terminal figure effectiveness of the stent . To address this issue , drug - eluting stent ( DES ) were develop in the other 2000s , which contain an anti - proliferative drug within a polymer coating on the stent to forbid neo - intimal hyperplasia.(5 )
Over metre , DES cover to acquire and bug out using biodegradable polymers in an attempt to reduce the risk of exposure of long - term inflammation and delayed healing due to lasting polymer software . This lead to the development of biodegradable polymer drug - eluting stents ( BP - DES ) and , more recently , polymer - free drug - eluting stents ( PF - DES ) that eliminate the need for any polymer coating.(6 )
Today , coronary stent continue to evolve , with ongoing inquiry focalize on improving the efficaciousness and safety of stents , reduce the risk of infection of stent thrombosis and restenosis , and expanding the use of stent in more complex character of coronary artery disease .
Design and Composition Of Polymer-Free Drug-Eluting Stents
Materials Used In Stent Fabrication (e.g. metals)
Polymer - free drug - eluting stent are commonly manufactured by using more or less the same materials that are used in the manufacturing of traditional drug - eluting stents ( DES ) . The stent scaffold , which is creditworthy for provide morphological reenforcement to the care for artery , is usually made from metal alloys , such as cobalt - chromium , platinum - Cr , or stainless steel.(7 )
The stent chopine is often coat with a layer of medication that is design to prevent restenosis , which is the recurrence of blockage within the treated artery . When compared to the traditional DES , polymer - spare drug - eluting stents does not involve a polymer coating to deliver the medication . Instead , the medication is immediately applied to the stent scaffold , usually using a thin layer of a bioabsorbable material such as atomic number 12 or atomic number 20 , or through a proprietary finishing technology.(8 )
Other materials used in the construction of polymer - free drug - eluting stents include radio-opaque markers that facilitate to visualize the stent position during the implantation process and other small features design to optimize the stent ’s functioning , such as thin struts and low jail cell sizes to improve the stent ’s flexibility and conformability to the artery.(9 )
Drug Delivery Mechanisms
Polymer - costless drug - elute stents ( PF - DES ) return medication directly to the arterial paries without needing a polymer coating . This is achieved through various mechanisms , include :
The medication used in PF - DES is unremarkably an anti - proliferative drug like sirolimus or paclitaxel , which helps to forbid restenosis by inhibiting the growth of cells in the arterial wall . The dose and duration of drug outlet can vary depending on the specific stent excogitation and the drug used .
Structural and Mechanical Properties
Polymer - free drug - elute stent are loosely made up of metals like unstained sword , Pt - chromium , or Co - atomic number 24 , which are bonk for their strength , flexibility , and their biocompatibility . These metal have been used in stent fabrication for many age and they have a prove racecourse disk of both safety and efficacy .
The structural and mechanically skillful properties of polymer - barren drug - eluting stents ( PF - DES ) are important considerations in stent blueprint . This is because they have an impact on the stent ’s power to adjust to the arterial paries , while also being able to withstand the emphasis of day-by-day function . It is important to keep in intellect that PF - DES must be strong enough to resist radiate compression , yet flexible enough to conform to the curving structure of the artery.(13 )
To attain these property , PF - DES may be designed with a change of features , such as :
Pharmacokinetics and Pharmacodynamics Of Polymer-Free Drug-Eluting Stents
Drug Release Kinetics
Polymer - free drug - elute stents make function of drug coatings that are straight apply onto the stent ’s surface without the use of a polymer carrier . The drug finish is typically a thin layer of the active pharmaceutical ingredient ( API ) mixed with a carrier wave that assist in the bond of the coat to the stent surface .
The drug release kinetics of PF - DES are affected by many important constituent , including the eccentric of drug , the coating thickness , the coating opus , and the stent design . PF - DES have been shown to have a more rapid initial drug passing compare to traditional polymer - based drug - elute stents ( DES ) . This is because the drug in PF - DES are not trap within a polymer matrix and are released immediately upon contact with the arterial tissue.(14,15 )
However , the drug release from PF - DES is also generally less sustained compare to traditional DES due to the absence of a polymer intercellular substance that can hold the drug release . This can result in higher rates of restenosis and other adverse result . To address this consequence , some PF - DES designs incorporate a drug source or a nano - thin coating that can help regulate drug release over a longer period of clip .
Tissue Drug Concentrations and Duration Of Drug Effects
discipline have exhibit that polymer - free drug - eluting stent release drug directly into the arterial paries without the penury for a polymer carrier . This leads to a more localized and sustained drug spillage , which can head to in high spirits tissue paper drug absorption and farsighted duration of drug effects liken to traditional drug - elute stent .
For example , a study release in EuroIntervention in 2016 compared the drug concentration in the arterial wall of patient handle with a PF - DES versus a traditional DES . The results showed that the PF - DES had high tissue paper drug concentration than the traditional DES at all meter points measure up to 180 days after implantation.(16 )
Another study bring out in the Journal of the American College of Cardiology in 2019 compared the length of drug effects of a PF - DES versus a traditional DES in patients with coronary arteria disease . The work see that the PF - DES had a longer duration of drug gist , with significantly broken rates of target lesion revascularization and target vesselmyocardial infarctionat three years after implantation.(17 )
Comparison with Traditional Drug-Eluting Stents
Polymer - complimentary drug - eluting stent have been developed as an option to traditional drug - eluting stents ( DES ) that use polymer covering to deliver drugs directly to the arterial wall . Numerous studies have been done to equate the safety and efficacy of PF - DES to traditional DES .
For example , a randomize controlled trial known as REMEDEE compared a PF - DES to a traditional DES in 1,140 participants with coronary arterial blood vessel disease . The discipline found that the PF - DES was non - inferior to the traditional DES in term of butt vessel failure at 12 months , and had similar rates of stent thrombosis , cardiac death , and myocardial infarction.(18 )
Another randomize controlled trial compared a PF - DES to a barren metal stent ( BMS ) in 2,466 patients who were at a high-pitched risk of hemorrhage . The cogitation found that the PF - DES was superior to the stool in terms of target wound loser at one twelvemonth , with a significant reduction in object lesion revascularization and myocardial infarct , but no significant conflict in stent thrombosis or cardiac death.(19 )
So far , these studies have read that PF - DES are a dependable and effective choice to traditional DES and BMS , and may provide advantages in specific patient role populations . However , more enquiry is still needed to in full understand the long - term base hit and efficaciousness of PF - DES .
Clinical Performance and Safety Of Polymer-Free Drug-Eluting Stents
Efficacy in Reducing Restenosis and Major Adverse Cardiovascular Events
There have been several clinical trial comparing the efficacy of PF - DES with traditional drug - eluting stent ( DES ) in reducing restenosis and major adverse cardiovascular result ( MACE ) such as myocardial infarction , aim lesion revascularization , and cardiac death .
One meta - analysis of 11 randomized insure trials including 9,103 patient role ground that PF - DES had similar rate of object lesion revascularization and MACE compared to traditional DES . However , the PF - DES had higher rate of definite or probable stent thrombosis compared to traditional DES at two eld of follow - up.(20 )
Another meta - analysis of 19 randomized controlled tribulation include 19,872 patients retrieve that PF - DES had similar rates of butt lesion revascularization , MACE , and stent thrombosis compared to traditional DES.(21 )
It can be said that the efficacy of PF - DES in reducing restenosis and MACE is likely almost similar to traditional DES , but there might be a slenderly high-pitched risk of stent thrombosis with PF - DES.(22 )
Comparison With Traditional Stents In Randomized Clinical Trials
Several randomised clinical trials have liken the efficacy and safety of polymer - gratuitous drug - eluting stent with traditional drug - eluting stents ( DES ) . Here are some examples :
Long-Term Safety And Potential Adverse Events
It is of import to know that the long - term safety and possible adverse upshot of polymer - free drug - eluting stents are not really well known yet . While they have been studied in various clinical trials , but more research is still required to confirm the results . Some of the potential minus outcome that have been take note include stent thrombosis , in - stent restenosis , and target area wound revascularization .
Several studies have present that PF - DES have comparable safety and efficaciousness to traditional drug - eluting stents ( DES ) in reducing untoward cardiovascular events . However , some studies have advise that PF - DES may have a high risk of stent thrombosis compared to traditional DES.(27 )
A study published in the Journal of the American College of Cardiology in 2018 compare the safety and efficaciousness of a PF - DES with a traditional DES in patient with coronary arterial blood vessel disease . The study found that the PF - DES was non - inferior to the traditional DES in terms of safety and efficacy.(28 )
Another recent sketch published in the Journal of the American Heart Association in 2021 compared the result of PF - DES with traditional DES in patients with acute coronary syndrome . The study find that there was no meaning difference in the incidence of stent thrombosis or objective lesion revascularization between the two groups.(29 )
So far , the useable grounds shows that PF - DES are a safe and efficient alternative to traditional DES in the discussion of coronary arterial blood vessel disease . However , there is still a need of more long - terminal figure studies .
Future Directions For Polymer-Free Drug-Eluting Stents
Ongoing Research and Development Efforts
There have been a heap of ongoing inquiry and developing sweat going on to research the potential drop of polymer - free drug - elute stent and to improve the rubber , efficaciousness , and durability of these devices . Some of the area of focus include :
Optimization of drug release dynamics : research worker are investigating various drug expression and coatings to achieve more logical and free burning drug release from PF - DES.(30 )
developing of refreshing stent textile : New material are being tested for their potential to improve the biocompatibility , mechanically skillful properties , and drug - elute capacity of PF - DES.(31 )
Determining long - term safety and efficacy : on-going clinical trials are monitor patients treated with PF - DES to assess their long - term outcomes and identify any potential safety concerns .
Improvements on imaging and symptomatic techniques : Improved tomography and diagnostic tools can facilitate identify patient role who are most potential to benefit from PF - DES and monitor their progress over time.(32 )
Personalized practice of medicine coming : Researchers are explore the potential for personalised medication approaches , such as genetic examination and biomarker psychoanalysis , to key patients who may be more likely to get restenosis or other complication and sartor treatment consequently .
Potential Clinical Applications and Advantages Over Traditional Stents And Bioresorbable Stents
Polymer - free drug - eluting stent definitely have the potential to overcome some of the limitations of both traditional stents and bioresorbable stents .
Some of the advantages of using PF - DES over traditional stent let in :
Some of the advantages of PF - DES over bioresorbable stents include :
When it comes to the potential clinical applications of PF - DES , patients at a gamey hazard for haemorrhage , those take shorter durations of threefold antiplatelet therapy , and those who have complex lesions that need expectant tractability and conformability of a stent may benefit from using PF - DES .
Conclusion
Summary of Key Points
Some of the primal gunpoint discussed here let in :
Polymer - free drug - eluting stents ( PF - DES ) are stents used in the treatment of coronary arterial blood vessel disease that do not contain a polymer coating like traditional drug - elute stents ( DES ) and bioresorbable stents ( BRS ) .
PF - DES make use of different material for stent prevarication , including metals like untarnished steel and cobalt chromium . They also make consumption of a slender software of drug on the stent surface that is released into the arterial tissue to preclude restenosis .
Clinical study have shown that PF - DES are comparable to traditional DES in term of reducing restenosis and major untoward cardiovascular events . However , they may have a higher risk of stent thrombosis and other complications , due to which further enquiry is still needed .
Ongoing research and development cause are focused on better the design and drug saving mechanisms of PF - DES to further heighten their safety and efficaciousness .
Clinical Implications and Considerations For Use In Patient Care
Polymer - free drug - eluting stent have show substantial promising results in reducing restenosis and major contrary cardiovascular events ( MACE ) during clinical tribulation . Compared to traditional drug - elute stents , PF - DES may have lower rates of stent thrombosis as they lack a polymer finish . However , further studies are still needed to confirm the long - term safety and potential untoward consequence tie in with PF - DES .
When it get to clinical implications , PF - DES may be a viable choice for patients with coronary artery disease who are at gamy risk for stent thrombosis or who have had untoward reaction to polymer - coated stents .
References :
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