Do Medical Stents Dissolve? Permanent vs. Bioresorbable

Most medical stents placed today are permanent. They are small mesh tubes made from metal alloys that stay in your body for life. But a newer category, called bioresorbable scaffolds, is designed to dissolve completely once the treated artery has healed, typically within two to four years. The idea is appealing: temporary support without a lifelong implant. The reality, though, has been rockier than early enthusiasm suggested, and understanding where things stand requires looking at what these devices are made of, how clinical trials have played out, and why the concept is far from dead despite some high-profile setbacks.

What Permanent Stents Are and Why They Became Standard

Permanent coronary stents emerged as a solution to a specific problem. Early balloon angioplasty could open a blocked artery, but the vessel had a tendency to recoil or close abruptly after the balloon was removed. Metal stents solved this by acting as scaffolding that held the artery open permanently. The first generation was bare metal, and while these prevented recoil, they introduced a new issue: the artery would sometimes grow tissue over and into the stent, gradually re-narrowing the vessel. This process, called restenosis, prompted the development of drug-eluting stents, which release medication to suppress that tissue overgrowth.

Modern drug-eluting stents use thin struts coated with biocompatible or absorbable polymers that carry the drug, and they have strong safety and efficacy track records after decades of refinement.¹ These remain the default choice for coronary procedures around the world. They work well, they are well understood, and cardiologists have extensive experience implanting them. So why try to replace something that works?

The Case for a Stent That Disappears

A permanent metal cage in your artery does its most important work in the first six to nine months, when the vessel is healing and most vulnerable to reclosure.² After that healing window, the metal serves no structural purpose but can still cause problems. Years later, a permanent stent can trigger very late blood clots or renewed tissue growth. It also “jails” any side branches it covers, complicates future bypass surgery by locking treated segments in a metal jacket, and creates artifacts on CT scans and MRIs that make follow-up imaging harder to interpret.

Bioresorbable scaffolds were designed to address all of this. The idea is to provide the same drug delivery and mechanical support as a metal drug-eluting stent during that critical first year, then gradually dissolve over two to four years, removing the long-term risks and leaving behind a vessel that can function more normally.³ There is also a less discussed but real consideration: some patients have cultural, religious, or personal objections to carrying a permanent implant, and bioresorbable devices address that concern.³

What Dissolvable Stents Are Made Of

The most widely tested bioresorbable material for stents is a polymer called poly-L-lactic acid, or PLLA. It is the same family of material used in some dissolvable sutures. PLLA breaks down through hydrolysis, meaning water gradually degrades the polymer chains into lactic acid, which the body metabolizes naturally. The challenge is engineering PLLA tubes that are strong enough to hold an artery open yet thin enough to implant through a catheter. Manufacturing processes like radial expansion can improve the mechanical properties of these tubes, but the technology still needs refinement to match the performance of metal stents in all scenarios.⁴

Metals can dissolve too. Magnesium-based alloys were among the first metallic bioresorbable materials explored, but they tend to corrode too quickly and unevenly, losing structural support before the artery has fully healed.⁵ Researchers have turned to coatings to slow this down. One approach uses a layered double hydroxide coating on magnesium stents, which in lab testing cut the average corrosion rate by about 95% compared to uncoated magnesium.⁶ Iron-based alloys offer better mechanical strength but dissolve far too slowly. Zinc alloys have emerged as a promising middle ground, with certain zinc-magnesium compositions showing a favorable balance of strength, flexibility, and degradation speed.⁵

The environment inside a living body also affects how fast these materials break down. Lab studies simulating physiological conditions have found that the composition of the surrounding fluid matters: protein-containing solutions that more closely mimic real blood tend to produce more protective corrosion layers on the metal surface, slowing degradation compared to simpler salt-based lab solutions.⁷ This is one reason why lab results and real-world performance do not always line up perfectly.

The ABSORB Saga and What It Taught Us

The most prominent bioresorbable scaffold to reach the market was Abbott’s Absorb, a PLLA-based device coated with everolimus. It generated enormous excitement. In a large trial comparing it to the standard metal everolimus-eluting stent (Xience), one-year results showed Absorb met the statistical bar for noninferiority: about 7.8% of Absorb patients experienced a target-lesion failure, compared to 6.1% for the metal stent.⁸ That looked close enough. But as follow-up extended, the gap widened. Blood clots forming on the scaffold (scaffold thrombosis) occurred at about double the rate seen with metal stents in the first year, and rates of repeat procedures climbed as time went on.

By seven years of follow-up in a separate head-to-head trial, the rate of repeat procedures to treat the same lesion was roughly twice as high in the bioresorbable group compared to the metal stent group.⁹ Abbott voluntarily pulled Absorb from the market in 2017. The technology had not delivered on the promise of superior long-term outcomes, and its thicker struts and implantation quirks made it riskier in less-than-ideal conditions.

Why Implantation Technique Matters So Much

One of the most important lessons from the Absorb era is that bioresorbable scaffolds are far more sensitive to how they are implanted than metal stents. A metal stent is forgiving: you can push it a bit harder, expand it a little more aggressively, and it flexes rather than fractures. Polymer scaffolds do not have that margin. Studies analyzing scaffold thrombosis events found that vessel sizing was the single most critical factor. Oversizing the scaffold relative to the vessel dramatically increased the risk of early blood clots, while undersizing it predicted late clots.¹⁰ When an optimal implantation technique was used, both early and late scaffold thrombosis dropped by roughly 80%.¹⁰

The technique that emerged from this analysis is often called PSP: pre-dilation of the artery before placing the scaffold, careful sizing to match the vessel diameter, and post-dilation afterward with a high-pressure noncompliant balloon. Retrospective studies found that following all three steps improved clinical outcomes significantly.¹¹ Yet in the original ABSORB trials, full PSP was used in only a fraction of cases. For example, proper post-dilation was performed in just over 12% of scaffold implants.¹² Proper vessel sizing alone was an independent predictor of better outcomes through three years of follow-up.¹²

This finding has reshaped how cardiologists think about the Absorb failure. The scaffold itself had real limitations, particularly its thick struts, but many of the adverse events were at least partly attributable to suboptimal placement. The principle of careful imaging-guided sizing and dilation now extends beyond bioresorbable devices. Research on standard metal drug-eluting stents in complex lesions has similarly shown that the PSP approach, guided by intracoronary imaging, leads to fewer cardiac events at three years.¹³

Where Bioresorbable Stents Are Showing Real Promise

While the coronary artery story has been humbling, bioresorbable scaffolds are gaining traction in other parts of the body where the case for temporary support is even stronger. One area generating genuine enthusiasm is below-the-knee arterial disease, which commonly affects people with diabetes and can lead to limb amputation. Arteries below the knee are small, and permanent metal stents in these vessels have a poor track record due to high fracture and restenosis rates.

A randomized trial called LIFE-BTK compared an everolimus-eluting bioresorbable scaffold to standard balloon angioplasty in patients with below-the-knee disease. At one year, about 74% of the scaffold group maintained vessel patency and avoided major events, compared to 44% of the balloon-only group.¹⁴ At two years, the advantage held: the scaffold group still showed substantially better efficacy, with lower rates of restenosis (about 29% vs. 48%) and fewer repeat procedures (roughly 10% vs. 19%).¹⁵ These are meaningful numbers in a patient population where the alternative is often losing a foot or leg.

Pediatric cardiology is another area where dissolvable stents make intuitive sense. Children with congenital heart defects sometimes need stents to hold open blood vessels or heart structures, but a permanent metal stent does not grow with the child. As the child grows, repeat procedures are needed to upsize or remove the original stent. Researchers have developed bioresorbable stent designs using dual opposing coils that can be scaled to the larger diameters needed for pediatric heart defects while maintaining adequate radial strength.¹⁶ The goal is a stent that does its job and disappears before the child outgrows it.

The Imaging Advantage

One practical benefit of bioresorbable scaffolds that often gets overlooked is how much easier they make follow-up imaging. Metal stents create bright artifacts on CT angiography and completely obscure the vessel on MRI, making it difficult or impossible to see whether the artery inside the stent is still open without performing an invasive catheter-based procedure. Bioresorbable scaffolds, being made of polymer or lightweight metals, do not produce these artifacts.

In vitro testing showed that two different polymer scaffolds (Absorb and DESolve) allowed essentially unrestricted visualization of the vessel lumen on both CT and MRI, with lumen measurements nearly identical to the unstented reference tube.¹⁷ In real patients, MRI was able to reliably assess vessel patency in all segments that had received a bioresorbable scaffold, both at baseline and after one year, while segments with metal stents could not be evaluated at all due to artifacts.¹⁸ For someone with a bioresorbable scaffold, this means follow-up can potentially be done with a noninvasive scan rather than threading a catheter back into the artery.

Vascular Healing Is More Complicated Than Expected

The theoretical promise of bioresorbable scaffolds included the idea that once the device dissolved, the artery would return to more normal function, including restoring a healthy inner lining (endothelium) and regaining the ability to expand and contract in response to blood flow. Early clinical studies showed promising results on this front, but with small sample sizes.¹⁹

However, the healing process during the absorption phase turned out to be slower and more complex than hoped. In animal studies, the Absorb scaffold showed less re-endothelialization at 28 days and more inflammatory cell adhesion at 14 days compared to the metal everolimus-eluting stent. Interestingly, only bare metal stents (with no drug coating at all) achieved complete re-endothelialization at that time point.²⁰ The drug that prevents restenosis also slows the regrowth of the protective cell layer, creating a tradeoff that exists in all drug-eluting devices but becomes more consequential when the scaffold itself is degrading and exposing new surface to the bloodstream.

Next-Generation Designs

The Absorb withdrawal was not the end of the story. Researchers have been working on next-generation devices that address its specific weaknesses. One major focus is thinner struts. The Absorb scaffold had struts about 150 micrometers thick, considerably bulkier than leading metal stents. Thinner struts mean less disruption to blood flow, less tissue overgrowth, and easier access to side branches. Zinc-alloy stents with ultra-thin center struts have shown less tissue overgrowth in animal models compared to thicker zinc stents, and they allowed easy balloon catheter access through the mesh at bifurcation points, with no stent fractures or particle emboli during deployment.²¹

Manufacturing methods are also evolving. Traditional stent fabrication involves cutting a pattern from a tube, but newer techniques like solvent-cast direct writing and electrospinning allow researchers to build stents layer by layer, controlling where and how drug is loaded. This dual approach can produce scaffolds where drug release from the bulk of the stent is slow and sustained over months, while a surface coating provides a fast initial burst of medication.²² Getting the drug-release profile right is one of the remaining engineering puzzles, because releasing too much medication too fast can impair healing, while releasing too little defeats the purpose.

What About Cost?

You might assume that a more advanced device that eventually disappears would be more expensive overall. In the short term, that assumption held true for the Absorb scaffold: the upfront procedural costs were higher than for metal stents. But at one year, total healthcare costs between the two groups in the ABSORB III trial were statistically indistinguishable, because the initial cost difference was offset by similar rates of follow-up care.²³ The hope was that longer-term savings would emerge after the scaffold dissolved and eliminated certain late complications, but the device was pulled before those data could materialize.

A separate cost analysis looked at a different product, an ultrathin metal stent with a bioresorbable polymer coating rather than a fully dissolvable scaffold. That device, which combines a permanent metal platform with a drug-carrying polymer that dissolves, showed a modest per-patient cost savings of about $124 compared to a standard durable-polymer metal stent, driven primarily by a slightly lower rate of procedure-related heart attacks during the initial admission.²⁴ It is worth noting the distinction: this is a permanent stent with a dissolving coating, not a fully dissolving scaffold. The cost story for a truly successful bioresorbable device, one that eliminates late events and repeat procedures, has not yet been written because no such device has had long enough follow-up in large enough populations.

Bioresorbable Polymer Coatings on Permanent Stents

The line between “permanent” and “bioresorbable” is not as clean as the marketing might suggest. Many current-generation metal stents already use bioresorbable polymer coatings. The metal stays forever, but the thin polymer layer that carries and releases the anti-restenosis drug dissolves over weeks or months, leaving behind a bare metal scaffold. This hybrid approach aims to get the best of both worlds: the reliable structural support of metal and the biological benefit of not leaving polymer on the artery wall permanently, since chronic polymer exposure has been linked to inflammation and late stent complications. These devices represent the current frontier of mainstream stent design and are widely available, even though they are not what most people mean when they ask whether stents dissolve.

If you or someone you know has been told a stent was placed, it is almost certainly a permanent metal device, possibly with one of these dissolvable coatings. Fully bioresorbable coronary scaffolds are not currently on the market in the United States, though several next-generation designs are in clinical trials in Europe and Asia. The concept has not been abandoned so much as sent back to the workshop, with thinner struts, better materials, improved implantation protocols, and more carefully selected patient populations informing the next round of attempts.