A cardiac stent is a small, mesh tube placed inside a coronary artery to physically prop open a blockage and restore proper blood flow to the heart muscle. This procedure is a common treatment for coronary artery disease, which involves the narrowing of arteries due to plaque buildup. While the physical device is intended to be a permanent fixture, the question of how long a stent lasts is better answered by considering its functional lifespan—how long it successfully keeps the artery open without complication.
Types of Stents and Physical Durability
The longevity of a stent depends on the material used for its construction. The first widely used devices were Bare-Metal Stents (BMS), which are simple stainless steel or cobalt-chromium alloy scaffolds designed to be permanent implants that do not degrade.
Drug-Eluting Stents (DES) are the current standard and are also designed to be permanent physical fixtures, similar to BMS. A DES is coated with a polymer that slowly releases anti-proliferative medication into the vessel wall to prevent tissue overgrowth. Both types become incorporated into the arterial wall, persisting for the patient’s lifetime.
A third, less common type is the Bioresorbable Vascular Scaffold (BVS). These scaffolds are made from materials like polylactic acid (PLLA) and are engineered to dissolve over time. The scaffold supports the vessel for a period, typically one to three years, before completely disappearing and leaving behind a restored artery.
Factors Determining Functional Lifespan
While most stents are physically permanent, their functional lifespan is limited by biological processes that can cause the artery to narrow again. The two primary mechanisms of functional failure are in-stent restenosis and stent thrombosis.
In-stent restenosis (ISR) is the gradual re-narrowing of the stented segment due to the overgrowth of scar tissue (neointima) inside the device. The initial stent placement causes mild injury to the arterial wall, triggering a healing response that can lead to excessive tissue proliferation. Restenosis tends to occur within the first three to six months after implantation, though it can happen years later.
Stent thrombosis (ST) is an acute form of failure involving the sudden formation of a blood clot within the stent, which can lead to a heart attack. It is often triggered by factors like incomplete stent expansion, disruption of the vessel lining, or premature cessation of antiplatelet medication. The risk of ST is highest within the first 30 days but remains a long-term concern, particularly for events occurring more than a year later.
The risk of functional failure depends heavily on factors beyond the stent itself. Underlying health conditions, such as diabetes and high blood pressure, contribute to disease progression and can shorten a stent’s functional duration. The complexity of the original blockage and the size of the treated vessel are also predictors of long-term success, as smaller vessels and complex lesions are more prone to ISR. With modern drug-eluting stents, the rate of functional failure is low, accumulating at roughly 2% per year after the first year.
Maximizing Stent Longevity Through Maintenance
The most significant action a patient can take to ensure the long-term functionality of a stent is strict adherence to prescribed medication, particularly Dual Antiplatelet Therapy (DAPT). DAPT involves taking a combination of aspirin and a P2Y12 inhibitor, such as clopidogrel, to prevent the formation of dangerous blood clots inside the stent. Stopping this therapy too early is a major driver of acute stent thrombosis, which can be life-threatening.
The required duration of DAPT is personalized based on the patient’s circumstances and the type of stent placed. For patients with stable heart disease receiving a drug-eluting stent, the P2Y12 inhibitor is recommended for at least six months. Patients who experienced an acute coronary syndrome, such as a heart attack, generally require at least 12 months of DAPT. In cases where the risk of blood clots is high and the risk of bleeding is low, the therapy may be extended beyond a year.
Beyond medication, managing the underlying conditions that caused the artery to narrow is important for maximizing longevity. Lifestyle modifications, including smoking cessation, adopting a heart-healthy diet, and engaging in regular exercise, help slow the progression of atherosclerosis throughout the coronary tree. Controlling conditions like high cholesterol and diabetes is also necessary, as these diseases accelerate plaque buildup and inflammation, which can affect the stented segment and other vessels.
Recognizing and Addressing Stent Failure
When a stent begins to fail functionally, the patient often experiences a return of symptoms similar to those that prompted the original intervention. This can manifest as recurrent chest pain (angina), pressure or tightness in the chest, shortness of breath, unexplained fatigue, nausea, or an irregular heartbeat. Since these symptoms mimic the original heart condition, any recurrence warrants immediate medical evaluation.
Diagnosis of stent failure, whether from restenosis or thrombosis, is typically confirmed through a procedure called coronary angiography. This imaging test allows physicians to visualize the coronary arteries and the stent itself to determine the extent and location of the re-narrowing or blockage. In some cases, advanced imaging tools like intravascular ultrasound (IVUS) or optical coherence tomography (OCT) are used during the angiography to identify the precise mechanism of failure.
If the functional failure is confirmed, several options are available for re-intervention. For restenosis, a common approach is to perform another balloon angioplasty to re-expand the narrowed segment. Often, a second stent is placed inside the first one, a technique known as stent-in-stent, which is frequently a drug-eluting stent to minimize the chance of a third narrowing. In complex cases or when multiple re-interventions have been unsuccessful, coronary artery bypass graft (CABG) surgery may be necessary to route blood flow around the blocked segment entirely.