Coronary artery disease (CAD) develops when the arteries supplying blood to the heart muscle become narrowed or blocked, reducing blood flow and potentially leading to symptoms like chest pain or shortness of breath. Stents aim to restore blood flow. The decision to use a stent is a nuanced process, considering various patient-specific factors rather than a single measurement.
Understanding Arterial Blockages
Arterial blockages are primarily caused by atherosclerosis, a condition where plaque accumulates within the walls of the coronary arteries. This plaque is composed of substances like cholesterol, fats, and calcium. Over time, this buildup hardens and narrows the arteries, a process often described as “hardening of the arteries.”
The gradual accumulation of plaque restricts the space available for blood to flow through the arteries. This narrowing can reduce the supply of oxygen-rich blood to the heart muscle. If a plaque ruptures, it can trigger the formation of a blood clot, which may further obstruct blood flow or even completely block an artery.
Such blockages can lead to myocardial ischemia, a condition where the heart muscle does not receive enough oxygen. This can manifest as stable angina, which is chest pain or discomfort that occurs predictably during physical exertion. A complete blockage, particularly if sudden, can result in a heart attack.
Diagnosing Blockages
Healthcare providers employ various diagnostic methods to identify and assess the extent of arterial blockages. Non-invasive tests are often the first step in this evaluation.
An electrocardiogram (ECG) measures the heart’s electrical activity, while an echocardiogram uses sound waves to visualize heart structure and function, helping to identify areas with reduced blood flow. Stress tests, which can involve exercise on a treadmill or medication to simulate exertion, assess how the heart performs under increased workload. These tests can reveal blockages that only become apparent when the heart’s demand for blood increases.
A CT angiogram is another non-invasive option, providing detailed 3D images of the heart and its blood vessels to pinpoint blockages and assess plaque buildup.
For a more definitive assessment, an invasive coronary angiogram is considered the gold standard. During this procedure, a catheter is threaded through a blood vessel to the heart’s arteries. A contrast dye is then injected, making the arteries visible on X-ray images, which allows direct visualization of blockages. Functional tests like Fractional Flow Reserve (FFR) and Instantaneous Wave-free Ratio (iFR) can be performed during an angiogram to measure blood pressure and flow across a narrowing, determining its physiological significance.
Determining Stent Need
The decision to place a stent in a coronary artery is based on several factors, not solely on the percentage of blockage. A common guideline suggests intervention for blockages of 70% or more (stenosis) in a major coronary artery. This degree of narrowing often causes significant restriction of blood flow.
Blockages ranging from 50% to 69% may also warrant a stent, particularly if the patient experiences notable symptoms such as angina (chest pain) or shortness of breath despite medical therapy. Functional tests like FFR or iFR are particularly useful in these cases. An FFR value below 0.80 or an iFR value below 0.89 indicates that the blockage is significantly impairing blood flow to the heart muscle, even if the anatomical narrowing appears less severe.
Other elements influencing the decision include the blockage’s specific location, such as in the left main coronary artery, which supplies a large portion of the heart muscle. Blockages in this artery are often considered more concerning due to their potential impact on overall heart function. The type of plaque, whether stable or vulnerable to rupture, and the patient’s overall health status, including other medical conditions, also play a role.
Managing Less Severe Blockages
When an arterial blockage does not meet the criteria for immediate stent placement, management typically focuses on lifestyle modifications and medical therapy. These strategies aim to slow the progression of atherosclerosis, alleviate symptoms, and prevent future cardiac events.
Adopting a heart-healthy diet, rich in fruits, vegetables, and whole grains, while limiting unhealthy fats, can help manage cholesterol levels and reduce plaque buildup. Regular physical activity strengthens the heart and improves overall cardiovascular health. Quitting smoking is crucial, as tobacco use damages blood vessels and increases heart disease progression risk.
Maintaining a healthy weight and managing conditions like high blood pressure and diabetes are additional components of a comprehensive management plan. Medications are prescribed to complement lifestyle changes.
Statins lower cholesterol and reduce plaque formation, while antiplatelet agents like aspirin prevent blood clots. Blood pressure medications and other drugs like nitrates can manage symptoms like chest pain and reduce the heart’s workload. Regular follow-up appointments are important to monitor the condition and adjust treatment.