Unveiling the Secrets of Microvascular Coronary Artery Disease and a Complete Guide to Stent Selection

Case Study: Do You Understand Microvascular Coronary Artery Disease? Ms. Wang, 66 years old, suffered from chest pain for many years. Her chest pain and tightness began five years ago. She was diagnosed with coronary artery disease at several hospitals and received symptomatic treatment, but the chest pain fluctuated and never fully resolved. To clarify the cause, Ms. Wang underwent coronary angiography, but the results were normal. Sometimes even her children thought she was faking it, which caused her great distress.

Later, the patient came to our hospital for treatment. After myocardial echocardiography and cardiopulmonary exercise testing, she was diagnosed with myocardial microcirculation disease. Simply put, the main blood vessels of her heart were normal, but the microvessels were dysfunctional, causing the chest pain.

Therefore, Dr. Zhou prescribed Tongxinluo capsules and nicorandil, among other medications. One week later, the patient's chest pain disappeared. Currently, the patient is taking Tongxinluo capsules regularly, and the chest pain has not recurred.

What is Microvascular Disease? Clinical examinations such as coronary angiography and coronary CT angiography can only visualize the main coronary arteries with a diameter >0.4-0.5 mm. Coronary angiography alone cannot evaluate the microcirculation of the coronary arteries supplying the heart, such as small vessels and capillaries. Clinical studies have found that more than 50% of patients with chest pain have normal main coronary arteries but suffer from myocardial microvascular disease. Even if coronary angiography does not show significant narrowing of the vessels, patients still have a high risk of cardiovascular events with serious consequences.

How is Myocardial Microcirculation Disease Treated? Currently, evidence regarding the treatment of microvascular disease is scarce. The main treatment methods are blood pressure control, antiplatelet therapy, and the use of drugs such as beta-blockers, calcium channel blockers, and nicorandil. However, the efficacy and indications for their use remain controversial.

In recent years, integrated traditional Chinese and Western medicine treatments have achieved some results. The research project "Construction of Traditional Chinese Medicine Collaterals Theory and Its Guidance for the Prevention and Treatment of Microvascular Disease" won the first prize of the 2019 National Science and Technology Progress Award. This represents a significant achievement of Traditional Chinese Medicine (TCM) in the field of microcirculation. This case demonstrates the effectiveness of using the traditional Chinese medicine Tongxinluo capsules combined with nicorandil to improve myocardial microcirculation, achieving good clinical results.

If you live in an area with poor tap water quality, over time, a lot of dirt will accumulate on your water pipes, causing blockages. To keep the pipes clear, in addition to improving water quality, you also need to regularly clean the dirt inside the pipes. Similarly, in the human body, excessive blood lipids and blood sugar can deposit under the inner lining of blood vessels, forming plaques that block the vessels and, in severe cases, lead to myocardial infarction. For good health and to avoid disease, it is essential to treat plaques in blood vessels promptly. Besides medication as a common treatment, a crucial method for quickly and effectively relieving narrowing and opening blood vessels is stent implantation.

This principle seems simple, but many patients still have doubts. Furthermore, the excessive demonization of cardiac stents by online rumors significantly affects patients' attitudes towards this treatment. For many patients with acute myocardial infarction, time is of the essence. Interventional surgery, which should be performed with every second counting, is often delayed due to online rumors, causing patients or their families to hesitate and miss the optimal treatment window. Therefore, it is crucial to understand coronary stents correctly.

When should coronary artery disease patients have stents implanted, and how should they choose a stent? In recent years, the incidence of coronary artery disease in my country has exploded. Many patients have already had stents implanted or are facing the need for stent implantation. Because patients lack professional medical knowledge, reading articles online only exacerbates their hesitation and anxiety. Dr. Zhou will address two questions that coronary artery disease patients urgently want answered.

1. Acute Myocardial Infarction
When a patient is diagnosed with acute myocardial infarction, they should not hesitate. If possible, a stent should be implanted as early as possible to open the blood vessel. As the blockage persists, the area of ​​myocardial necrosis increases, potentially leading to heart failure in mild cases and sudden death in severe cases.

2. Coronary Artery Stenosis

If a patient has coronary artery stenosis, the previous standard for stent implantation was a stenosis of >75% in the vessel lumen. However, currently, it is believed that if there are no symptoms and few risk factors, drug therapy can be used, and the decision to implant a stent still needs to be made by a doctor. If the stenosis is severe (>75%) and there are clear symptoms of myocardial ischemia, stent implantation is recommended.

How Patients Should Choose Different Types of Stents: Coronary stents originated in the 1980s and have undergone a development process including bare-metal stents (BMS), drug-eluting stents (DES), and biodegradable stents. Their main materials are stainless steel, cobalt-chromium alloy, or nickel-titanium alloy.

1. Bare-Metal Stents: The first generation of coronary stents, entirely made of metal, were the earliest coronary artery stents used clinically. Due to their relatively high restenosis rate, they are now rarely used, only in special cases such as when patients have a bleeding tendency.

2. Drug-Eluting Stents: The advent of drug-eluting stents was precisely to solve the problem of re-lesioning of blood vessels after bare-metal stent implantation. Simply put, some drugs are coated on the stent to prevent stenosis of the blood vessel. The next generation of drug-eluting stents excels primarily in drug release regulation.

3. Biodegradable Stents These are entirely composed of biodegradable materials and are a relatively new type of stent that has recently gained traction. They provide strong support to blood vessels in the short term after treatment, and once the vessel has remodeled well, the stent degrades directly into water and carbon dioxide within the body. However, there is currently no evidence to suggest that their long-term efficacy is superior to drug-eluting stents, and some biodegradable stents have been discontinued due to various issues. Nevertheless, this remains a potential future direction.

In general, patients should not be overly concerned about the choice of cardiac stent. The fundamental goal is to clear blocked blood vessels and treat the lesion; subsequent management of risk factors and rehabilitation are even more important.