Coronary artery disease is a major health care and economic burden in the United States. Acute coronary syndrome (ACS) comprises a spectrum of hemodynamically significant coronary artery disease that most commonly arises from plaque rupture and/or erosion, leaving the lipid-rich plaque core exposed to the circulation. This leads to a cascade of events, including activation of platelets and the coagulation cascade, which can cause acute thrombotic occlusions. Percutaneous coronary intervention (PCI) remains the preferred modality for the treatment of ACS
Percutaneous balloon angioplasty was first proposed in the late 1970s as an alternative to coronary artery bypass grafting (CABG) for the treatment of coronary artery disease. This novel idea faced many limitations due to the high risk of abrupt vessel occlusion and vascular wall recoil, requiring many of the first patients to need emergent bail out cardiothoracic surgery. Due to these issues, balloon angioplasty continued to take a back seat to CABG for patients with obstructive coronary disease. This changed when bare-metal stents (BMS) were first introduced. BMSs have their own advantages and disadvantages. One of the main disadvantages is the excessive neointimal hyperplasia that leads to a gradual loss of initial lumen gain. The increased need for subsequent repeat revascularization emerged as a limiting factor for the use of BMS in the 1990s. Then the third revolution of interventional cardiology occurred in the early 2000s; the advent of drug-eluting stents (DES). DES allows a site-specific controlled release of antiproliferative agents, which inhibits neointimal tissue formation. These stents also maintain the radial strength and scaffolding properties of the bare-metal stent allowing luminal gain to be maintained. The three important components of DES are platform, antiproliferative agent, and polymer coating. As time has progressed, there have been many continued technological advancements, including several new-generation DES with thinner stent struts, wider cell design, biodegradable polymer coating, and new antiproliferative agents for better clinical outcomes.
The key anatomical components of a coronary artery stent are platform, polymer coating, and released drug. The stent platform provides radial strength, flexibility, and radio-opacity. The stent polymer acts as a stable reservoir and modulates the release of drugs. The third component is the actual drug compound, which has an antiproliferative characteristic to inhibit smooth muscle proliferation. Over time, there have been several advancements in coronary artery stents in each anatomical character described above. Newer stent platforms are made of either cobalt-chromium or platinum-chromium, whereas early generation stents were made of stainless steel. This has allowed manufacturers to drastically reduce strut thickness and improve deliverability. New generation stent design also has a better mechanical performance profile, which has enhanced clinical outcomes. In addition to the reduction of stent strut thickness, the development of polymer coating technology has allowed for a more controlled release of the antiproliferative agent as well as reduced long term stent strut thickness. A polymer coating is either hydrophobic or hydrophilic, as well as bioabsorbable. Newer stents have a combination of these characteristics that enhance drug-eluting properties. The third component of DES is the actual antiproliferative drug, which historically has been either sirolimus or paclitaxel. Some studies have shown sirolimus and other similar agents to be superior compared to paclitaxel in reducing neointimal inhibition as well as stent restenosis, but the risk of thrombosis and myocardial infarction (MI0 were the same. Most new generation DES use sirolimus like analogs such as everolimus, zotarolimus, biolimus, or novolimus.
Intersocietal accreditation commission is a non-profit organization that accredits facilities that perform interventional cardiovascular procedures.
Additional cardiac catheterization lab equipment details are out of the scope of this article.
After the patient is prepared for the procedure, continuous vital signs monitor will occur as well as intravenous fluid administration and appropriate anticoagulation. Depending on the preferred access, multiple anatomical sites will be cleaned and sterilized. Initially, diagnostic angiography will be performed, and once a significant lesion is identified, the procedure will proceed to intervention if indicated. The intervention will involve the use of a guiding catheter, coronary wire, and a balloon angioplasty catheter to pre-treat the lesion. After angioplasty, the interventionalist will decide if a coronary stent is indicated. A more detailed description of this technique is out of the scope of this article.
There are multiple stents' models (at least 16) approved by FAD from multiple different manufactures. Types of coronary artery stents which are currently approved in the USA include:
Coronary guidewires are designed to navigate blood vessels to reach the segment of a vessel or the lesion in the vessel. Coronary wires are generally 0.014 mm in diameter and introduced to the coronary tree via a guiding catheter. Multiple different coronary wires exist described as "workhorse," "extra supportive," or "hydrophilic."
Newer generation drug-eluting stents have a great safety and efficacy profile. Specific subgroups of patients with markedly complex anatomical and clinical characteristics present a higher risk of complications. These are the characteristics for which further margins of improvement are indicated:
Bare-metal Stent: Circumstances in which bare-metal stent (BMS) may be reasonable have considerably decreased since the advent of drug-eluting stents. Some experts recommend BMS in situations like:
Drug-eluting Stent: First-generation drug-eluting stents (DES) are no longer used in the USA, Europe, and Canada since advancements in stent platforms and polymer biocompatibility found in newer DES listed above. For most patients undergoing coronary artery intervention with stent placement, current-generation DES are used.
Primary percutaneous coronary intervention with drug-eluting stent implantation is indicated to patients with acute MI according to the recent clinical guidelines. Evidence showed improved outcomes with new-generation DES as compared to early-generation DES and bare-metal stents. The risk of stent-related complications is relatively still higher than patients with stable coronaries.
There are several advancements in drug-eluting stents. Vessel size among patients with acute MI is either underestimated or overestimated due to vessel wall correction or pressure of thrombus between the vessel wall and stent platform. To negate this issue, self-expanding stents that adapt to the size of the artery were developed. The role of fully biodegradable stents is under extensive study. Further studies are indicated to improve clinical outcomes in diabetic patients with a diffuse disease requiring DES either introducing novel DES with higher restenotic activity or fully bioresorbable scaffolds. For coronary bifurcation disease, these are several techniques, but in 2019 meta-analysis showed DK crush technique to reduce stent-related events compared to others.
Revascularization with percutaneous coronary intervention as opposed to coronary artery bypass graft surgery:
There are several other determining factors that are taken into account to determine percutaneous coronary intervention as opposed to coronary artery bypass graft (CABG).
A percutaneous angioplasty with coronary artery stent placement has several procedural/stent-related complications and late complications.
There are several other procedural complications like coronary artery dissections, intramural hematoma, myocardial ischemia, myocardial infarction, access site bleeding, retroperitoneal hematoma, atheroembolism, acute kidney injuries, strokes, hypersensitive reactions, arrhythmia. All the complications in detail are explained in the percutaneous coronary intervention procedure section.
Coronary Artery Stent-related Complications
Failure of stent deployment is a serious problem associated usually with first-generation stents. It occurs in 2.0 to 8.3 percent of the procedures performed. Failure of stent deployment with dislodgment from the balloon tip leads to serious complications. Several studies have shown second, and third-generation stents have a higher rate of successful deployment.
Stent Thrombosis: Stent thrombosis is a serious complication that leads to myocardial infarction or death. This is a medical emergency and should be managed per protocols. Stent thrombosis is classified into acute, subacute, or late. If the thrombosis occurs during the PCI or within a few hours of the procedure, it is termed as acute. Subacute thrombosis is when it occurs within 30 days of stent placement. Late thrombosis is defined as thrombosis that occurs 1 year or later and is often associated with a drug-eluting stent. Stent thrombosis has been associated with premature cessation of dual antiplatelet therapy.
Stent Infection: Coronary artery stent Infections are rare but are potentially catastrophic complications. These infections can lead to coronary perforations and mycotic aneurysms.
Coronary artery aneurysm is a very rare complication mostly associated with drug-eluting stents.
A large meta-analysis of several randomized control trials was done comparing short-term and long-term outcomes of drug-eluting stents and bare-metal stents, which reported a reduction in myocardial infarction rate and stent thrombosis with DES compared to BMS. The study reported a rate ratio, 0.51 with a 95% credibility interval of 0.35 to 0.73. [CEBM Level 1]
An interprofessional team compromising of nursing staff, home health caregivers, and primary care physicians should have an integrated postoperative care plan from the operating cardiologist. In all patients, dual antiplatelet therapy is indicated to prevent stent thrombosis. Medication compliance is of utmost importance.
Patients with bare-metal stent need at least 1 month of dual antiplatelet therapy (DAPT)) versus drug-eluting stent need 6 to 12 months and in patients with a low risk of bleeding complications 18 to 24 months is recommended. In a recently published study, 1 to 3 months use of DAPT did not increase odds of postoperative stent-related complications but reduced odds of any bleeding by 30%. The risk of stent thrombosis is a lethal complication of coronary artery stent placement. A major adverse cardiac event such as cardiac death, MI, or stroke diminishes with the use of DAPT.
Pharmacy consultation–medication safety directions, educating patients’ importance of compliance, home health care counseling on diet and exercise modification.
Primary care physicians should be updated, performing accurate medication reconciliation on discharge, medical records, and plan of care should be sent over to primary care physician for continuity of care. Schedule the patient for follow up within 3 days. Cardiology follow-up in 1 to 2 weeks.
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