Coronary artery blockages are a common concern, often prompting questions about when a stent is needed. The decision to place a stent is multifaceted, extending beyond a single percentage. It involves a comprehensive evaluation of a patient’s overall health and the functional impact of the blockage on heart function.
Understanding Coronary Artery Blockages
Coronary artery blockages develop due to atherosclerosis, a condition where plaque, made of fat, cholesterol, and other substances, builds up inside the arteries that supply blood to the heart. This accumulation narrows the arteries, restricting blood flow to the heart muscle. The severity of these blockages is often expressed as a percentage of narrowing.
Blockages are typically identified and measured through diagnostic procedures. Coronary angiography, also known as a cardiac catheterization or angiogram, is a primary method. During this procedure, a thin tube, or catheter, is guided to the heart, and a contrast dye is injected to highlight the arteries on X-ray images, allowing doctors to visualize and assess the extent of any narrowing.
The Significance of Blockage Percentage
Many people associate a 70% blockage of a coronary artery with the need for a stent. This figure serves as a general guideline for significant narrowing that often warrants consideration for intervention. This 70% threshold became a common benchmark because it historically correlated with a point where blood flow to the heart muscle could be substantially impaired, especially during physical activity.
However, relying solely on this percentage can be misleading as it represents an anatomical measurement. Not all blockages of the same percentage affect blood flow or patient symptoms equally. Medical decisions are more nuanced, involving various additional factors beyond this numerical guideline. Some blockages below 70% might still cause significant issues, while others at or above this percentage might not.
Factors Influencing Stent Decisions Beyond Percentage
The decision to place a stent extends beyond the visual percentage of a blockage, incorporating several other crucial factors. A patient’s symptoms are paramount; chest pain (angina) or shortness of breath, particularly if severe or unresponsive to medication, can indicate a need for intervention regardless of the exact percentage. The location of the blockage within the coronary artery system also plays a significant role. Blockages in major arteries, especially the left main coronary artery, are considered more critical due to their extensive blood supply to the heart.
Functional significance testing provides a deeper understanding of how a blockage impacts blood flow to the heart muscle. While an angiogram shows anatomical narrowing, functional tests like Fractional Flow Reserve (FFR) or Instantaneous Wave-free Ratio (iFR) measure the actual blood pressure and flow across the blockage. An FFR value below 0.80 indicates the blockage is functionally significant and restricts blood flow, even if anatomical narrowing appears intermediate. These tests help determine if a blockage truly limits blood supply, guiding the decision for stenting or medical management. Patient health, including age, co-existing conditions like diabetes or kidney disease, and individual preferences, are also considered.
When Stents Are Considered
Stents are small, mesh-like tubes inserted to open blocked arteries and restore proper blood flow to the heart. They act as scaffolds, preventing the artery from narrowing again after the procedure. Stent placement is considered for significant blockages causing symptoms like chest pain or shortness of breath, or those identified as functionally significant through tests like FFR. They are also used in emergencies, such as during a heart attack, to quickly reopen a blocked artery.
There are two main types of coronary stents: bare-metal stents (BMS) and drug-eluting stents (DES). Bare-metal stents are metal mesh tubes, while drug-eluting stents are coated with medication that releases into the artery wall. This medication helps prevent the overgrowth of tissue that can lead to re-narrowing of the artery, a process called restenosis. Drug-eluting stents have largely replaced bare-metal stents due to their lower restenosis rates, though bare-metal stents may still be used in specific situations.
Other Treatment Options and Post-Procedure Care
Stenting is one of several approaches to managing coronary artery disease. For less severe blockages not causing significant symptoms or functionally limiting blood flow, medical management is often the primary treatment. This involves lifestyle changes: a heart-healthy diet, regular exercise, and quitting smoking. Medications also include those to lower cholesterol, manage blood pressure, and prevent blood clots.
For more complex or extensive blockages, or when stenting is not suitable, coronary artery bypass graft (CABG) surgery may be recommended. This open-heart procedure creates new pathways for blood to flow around blocked arteries using healthy blood vessels. After a stent procedure, post-procedure care is important. Patients are prescribed antiplatelet medications, often a combination of aspirin and another drug, to prevent blood clots from forming on the stent. Continuing lifestyle modifications, including diet and physical activity, remain important to prevent future blockages and support long-term heart health.