What is Complex Coronary Artery Lesions?
The modern approach to treating heart disease heavily relies on a method known as percutaneous coronary intervention (PCI) and medical management. PCI techniques, which have developed substantially over time, are now used to place stents in even tough-to-reach places. However, some parts of the heart are still difficult to access with traditional PCI methods. These tricky areas of the heart are categorized by their physical, physiological, or functional problems.
These problem spots in the heart can include areas like bifurcation lesions, calcified lesions, complete blockages, unprotected left main coronary artery lesions, ostial lesions, and saphenous vein graft narrowings. Each of these problem areas presents its own unique challenges, and the method used to treat them is often tailored to the individual patient. The success of treatment often depends on cardiologists with advanced skill sets and the use of specialized techniques.
Sometimes, the traditional method of PCI isn’t enough to treat these problem areas, and that’s when more advanced techniques might be required. One type of these specialized methods is called complex, high-risk, and indicated PCI (CHIP). These methods may include laser treatments, rotational treatments, laser atherectomy, different bifurcation stent techniques, and specialized approaches to chronic total blockages. While these methods look promising, the research is still unclear whether they have a positive effect on reducing death rates. According to some studies like Habib et al, coronary artery bypass grafting (CABG) may be a more effective method for treating these problem areas.
Let’s give a brief overview of some of the most common complex lesions:
* Bifurcation lesions: These are located at the point where a major coronary artery splits into two smaller arteries. These lesions occur when there is significant narrowing (> 50%) in a coronary artery that involves the origin of a side branch, or in an artery neighboring the origin of the side branch. The Medina classification is a numerical system used to assess and define the location of narrowing.
* Calcified lesions: These arise when vascular calcification of the heart arteries occurs, which is typically associated with inflammatory or hormonal diseases. The presence of coronary artery calcification (CAC) can stiffen the vessels and increase the likelihood of heart-related events.
* Chronic total occlusions: These are complete blockages in a heart artery and must show limited or no blood flow and have been present for at least 3 months.
* Left main coronary artery (LMCA) disease: This can be problematic since it is the source of most of the blood supply for the left heart muscle. An unprotected left main coronary artery can put most of the heart muscle at risk of death if significant narrowing is present.
* Ostial lesion: This type of lesion starts within 3 mm of the origin of a major coronary artery. These lesions can be difficult to treat with stents due to their proximity to the aorta.
* Stenosis of saphenous vein graft (SVG): Saphenous vein grafts are commonly used in bypass grafting. Narrowing of these grafts is common, and in some cases, up to 20% of patients might develop this within a year. Stenosis in these grafts can lead to significant risks, including a heart attack or reduced blood flow.
What Causes Complex Coronary Artery Lesions?
Each serious heart artery issue has different causes. For instance, bifurcation lesions, primarily occur due to the anatomical structure of the arteries. Hardening of these arteries can be a result of ingrained inflammation and the activity of cells responsible for forming bones. The existence of a clot can often occur from a damaged or ruptured artery plaque, either before or during a procedure to restore blood flow to the heart.
Thrombosis in a saphenous vein graft, a type of heart bypass surgery, is believed to be a process involving the growth of smooth muscle cells in the innermost layer of the blood vessel.
There are certain conditions that are common to each of these heart disorders. For example, diabetes and old age have been identified as common independent predictors for all complex heart artery issues. While other risk factors for heart artery disease and build-up of fats, cholesterol, and other substances in and on your artery walls (atherosclerosis), such as old age, high blood pressure, obesity, being male, smoking, and high cholesterol, exist but have not been directly identified in any significant studies as independent risk factors for complex heart artery issues.
Risk Factors and Frequency for Complex Coronary Artery Lesions
Coronary artery calcification refers to the build-up of calcium in the arteries, which can vary in severity. Most individuals have some level of artery calcification but not enough to cause significant blockage. Studies have shown that around 50% of people aged 40-49 and 80% of those aged 60-69 have some calcification. This condition is more common in older individuals and men, with about 93% of men and 77% of women over 70 having coronary calcification.
Coronary bifurcation lesions, a type of complex artery disease, are quite common and found in about 20% of all percutaneous coronary interventions (procedures used to unblock clogged coronary arteries). Chronic total occlusions (complete blockage of coronary arteries) are also very prevalent. They’re found in 20% of people undergoing emergency-free angiography, 47% of those with acute coronary syndrome, and 89% of individuals who’ve had coronary artery bypass grafting.
Statistics vary regarding unprotected left main coronary artery disease, occurring when there’s a blockage in the main artery that supplies blood to the heart. It’s estimated to affect 5% of individuals in one study, and less than 2% in another, who underwent coronary angiography (a test that uses dye and special x-rays to show the insides of your coronary arteries).
Another heart procedure, coronary artery bypass grafting (CABG), is performed on about 300,000 individuals in the U.S each year. Of these, 8-12% will have a blockage before even leaving the hospital. Within the first year after CABG, 15-30% of saphenous vein grafts (veins used to reroute blood around blocked arteries) become blocked. Approximately 60% of individuals experience graft failure within ten years of the surgery.
Signs and Symptoms of Complex Coronary Artery Lesions
People with complex coronary artery lesions often exhibit similar symptoms, with chest pain being the most common. It’s important to assess a person’s risk factors for heart disease by asking them about any previous vascular disease, obesity, diabetes, high blood pressure, age, high cholesterol, smoking habits, and family history of heart disease.
- Chest pain, usually felt as pressure, tightness, or heaviness in the middle or left side of the chest, which can extend to the neck, jaw, left shoulder, or left arm
- Shortness of breath
- Heart palpitations
- Feeling weak
- Feeling light-headed
- Nausea or vomiting
- Sweating
- Feelings of anxiety or a sense of impending doom
- Indigestion
Physical examination results can differ depending on whether the person has long-term heart disease or a recent unstable plaque. Therefore, it’s crucial to carefully evaluate each person during the physical examination. Some signs to look out for during the physical examination include:
- Fast heart rate
- High or low blood pressure
- Fever
- Swelling in the neck veins
- Crackling sounds in the lungs
- An extra sound in the heartbeat, known as an S4 heart sound
- A heart murmur sound when listening to the mitral valve
- A displaced pulse in the lower part of the heart
- Slow return of color to the fingertips after they’ve been pressed
- Swelling, particularly in the legs and ankles
Testing for Complex Coronary Artery Lesions
If your doctor suspects you have a complex heart disease like a coronary lesion, they will typically order different types of tests which can include laboratory studies, electrocardiography (ECG), stress testing, and coronary angiography.
For the laboratory studies, the tests aren’t specific to identifying complex coronary lesions. However, if these blockages have resulted in acute coronary syndrome (a severe condition caused by reduced blood flow to the heart), certain “heart-specific” markers like troponin T and troponin I might be elevated. These usually rise around 4 to 8 hours after the injury and peak between 12 and 24 hours.
An ECG test might also be done. The results can vary depending on each case. For example, about half of people with chest pain (angina pectoris) won’t show any immediate abnormalities on the ECG. However, those who do may show certain changes in the reading like ST-depressions and T-wave inversions. If the lesions cause unstable plaque, acute coronary syndrome might develop, showing a more significant elevation on the ECG readings. Prolongation of QTc interval is another possible finding in those with more severe heart muscle ischemia or damage.
Stress testing is another tool for those suspected of acute coronary syndrome. They might go through coronary angiography and possibly Percutaneous Coronary Intervention (PCI) – a non-surgical procedure that uses a catheter to place a small device in or around the heart to improve blood flow. However, if the diagnosis is still uncertain but the patient is stable, a form of stress testing might be useful. Exercise ECG is preferable, especially for people without resting ST-segment abnormalities. In cases where exercise isn’t possible, they might use a drug-induced stress test. A myocardial perfusion scintigraphy test is becoming more popular. It uses special markers to show the areas of the heart with reduced blood flow.
The gold standard in diagnosing coronary lesions is coronary angiography. It helps check the anatomy and the extent of the unhealthy blood vessels. It comes with some limitations, like vessel overlap and only limited visualization to the inside of the arterial wall. However, it’s the only reliable method to evaluate the degree of stenosis (the narrowing of the blood vessels) and to determine if any lesions can be treated with stenting. Complex lesions might be not appropriate for stenting and may need medication alone or further surgical evaluation.
Treatment Options for Complex Coronary Artery Lesions
Treatment of blockages in coronary arteries depends on the type of blockage:
If the blockage is in a saphenous vein graft, a type of bypass graft that tends to wear out faster than natural arteries, the treatment usually involves stents. Stents are small metal structures that help keep the artery open. Studies found that bare metal stents were better than balloon angioplasty, a procedure to widen the artery, in terms of process success, reducing the chance of the blockage reoccurring and reducing serious cardiovascular events. Yet, des stents (stents that release drugs into the body) helped to reduce the need for a repeat procedure and the blockage from returning. However, evidence suggests that bare metal stents might be as good or even better than des stents, especially in patients with certain characteristics.
For bifurcation lesions or blockages occurring at the branching point of arteries, many studies have shown that drug releasing stents are better than bare metal ones. Additionally, studies have highlighted that there isn’t much advantage in using two stents over one for these types of blockages. However, if a second stent is needed, certain techniques, like the DK crush method, might be beneficial.
When it comes to total blockages, or chronic total occlusions (CTOs), these are the most difficult cases to treat. Some studies have shown that medical treatment alone might just be as effective as medical treatment combined with a procedure to unblock the artery. However, other studies have suggested that conducting a procedure to unblock the artery could be beneficial in terms of symptom relief and lower heart attack rate.
When a critical artery supplying most of the heart muscle, the Left Main Coronary Artery (LMCA), is blocked, surgery in the form of coronary artery bypass graft (CABG) has been regarded as the conventional treatment, particularly for patients with stable chest pain. However, in specific circumstances, placing a stent via Percutaneous Coronary Intervention (PCI) may be considered as an alternative to surgery. This would mostly apply to patients with certain clinical features or those who are poor surgical candidates.
For high-risk and complex blockages, mechanical support in the form of an extracorporeal membrane oxygenation (ECMO) is often considered in patients who are at an extremely high risk and who are not ideal candidates for surgery.
Newer generation drug-releasing stents, which have more body-friendly coatings, thinner struts, and release lower doses of drugs, are now being explored. These characteristics should theoretically reduce inflammation and promote natural healing within the artery. Bioresorbable stents that dissolve into harmless substances after the artery has been widened are also being researched.
What else can Complex Coronary Artery Lesions be?
When determining the cause of severe heart problems, doctors have a wide range of potential illnesses to consider. These possible conditions may cause symptoms like chest pain, shortness of breath, heart racing, or other signs that your heart isn’t getting enough blood. Some things doctors might have to rule out include:
- Aortic dissection – a severe condition where the main artery from your heart tears
- Gallbladder inflammation
- Severe anxiety
- Gallbladder pain
- Costochondritis – inflammation of the cartilage in your rib cage
- Chronic obstructive pulmonary disease (COPD) flare-ups
- Esophageal spasms – sudden, painful contractions in the tube that connects your mouth to your stomach
- Esophagitis – inflammation that damages the tube running from the throat to the stomach
- Acid reflux disease
- Myocarditis – inflammation of the heart muscle
- Pericarditis – swelling and irritation of the thin covering of the heart
- Prinzmetal angina – a type of chest pain caused by spasms in the coronary arteries
- Pneumonia
- Pulmonary embolism – a blockage in one of the arteries in the lungs
- Pneumothorax – a collapsed lung
These conditions can have similar symptoms, so doctors need to perform thorough assessments to make the right diagnosis.
What to expect with Complex Coronary Artery Lesions
Patients with stable angina who have complex coronary lesions face a higher risk of mortality compared to those with simpler lesions. These complex lesions are often seen in patients who have diabetes, a lower measure of blood pumped from the heart (ventricular ejection fraction), or lower ‘good cholesterol’ levels (HDL-C).
To decide on the best approach to restore blood flow (revascularization), doctors often use tools like the SYNTAX Score and SYNTAX Score II. These scoring systems are commonly used and their accuracy and usefulness have been confirmed in many studies. Research suggests that the SYNTAX Score II is especially good at predicting patient outcomes compared to the original SYNTAX Score.
Possible Complications When Diagnosed with Complex Coronary Artery Lesions
Coronary artery dissection is a complication connected to the procedure known as percutaneous transluminal coronary angioplasty. Some types of coronary artery dissections might increase the possibility of vessel closure and heart attacks, depending on how severe the dissection is and how it impacts blood flow in the coronary arteries.
A coronary intramural hematoma is a condition that occurs when blood gathers in the media (middle layer) of a blood vessel. This condition is most effectively detected using intravascular ultrasound (IVUS), but it can also be identified through coronary angiography. These lesions might trigger acute coronary syndrome (a severe heart condition that requires immediate treatment), especially after a prior procedure known as Percutaneous Coronary Intervention (PCI).
Perforation of the coronary arteries is a potential, albeit rare, risk that can stem from the use of guidewires, atherectomy devices, and balloons used in PCI. Even though this complication is rare, it demands serious attention when it does occur. One substantial study found that this occurred in about 0.7% of cases, with most of these cases needing some form of intervention, such as sustained balloon inflation or the reversal of anticoagulation therapy. Regardless, the overall rates of illness and death were quite low in these cases.
The severity of the perforation defines the prognosis. The types of perforations can be divided into:
- Class I – It involves an intramural crater (an inner wall defect) with no spillage and has a very low risk of leading to heart attacks.
- Class II – These are perforations measuring 1 mm or more with cavity spillage.
- Class III – These lesions could be associated with up to a 50% chance of leading to heart attacks.
Preventing Complex Coronary Artery Lesions
Patients should take an active role in their own healthcare. Due to the serious risks that come with complex heart conditions, it’s important for healthcare providers to have thorough discussions with their patients. These discussions should involve detailed explanations of how to manage these conditions, all potential treatment options, and any associated risks or complications. This includes conversation about medical, surgical, and other intervention options. The aim is to ensure the patients understand their condition and its management thoroughly.