Coronary Artery Disease
CAD is a condition in which plaque, which is made up of fat, cholesterol, calcium and other substances in the blood, builds up inside the coronary arteries which supply oxygen-rich blood to the heart muscle. This plaque build-up is called atherosclerosis. Plaque can grow large enough to reduce blood flow through an artery. The chest pains of angina occur when the heart cannot get enough oxygen-rich blood through plaque-clogged arteries although blockages do not always lead to symptoms (“silent ischemia”). While atherosclerosis occurs over many years, life-threatening damage to heart muscle supplied by arteries with plaque can occur in minutes, sometimes with no prior warning. A piece of plaque can break off at any time and totally block a narrowed artery, causing a heart attack.
Arteries are essentially tubes or pipes and the inner, central and open part of the artery is referred to as a lumen. Arteries that feed blood to the heart are referred to as coronary arteries. At a certain point (usually when the blockage is at least 60 to 70% of the circular lumen area of a coronary artery) the heart muscle can’t get adequate blood or oxygen that it needs, especially when it has to work harder such as during exercise. This can lead to symptoms such as chest pain (angina), or when severe enough, a heart attack, where permanent heart damage occurs.
While plaque can gradually grow large enough to completely block blood flow through an artery, more frequently, a plaque may suddenly break or rupture, causing a blood clot to form (from blood cells called platelets clumping at the site of rupture to, ironically, repair the artery) that blocks a coronary artery. Most heart attacks occur when this blood clot suddently cuts off part of the heart’s blood supply. How much heart muscle damage occurs depends on if the body can open up the blockage or get rid of the clot and how much heart muscle is supplied by the coronary artery that is blocked. A heart attack can result in sudden cardiac death (SCD) due to sudden life-threatening arrhythmias caused by dying heart muscle cells. While heart attacks occur more commonly in older individuals, tragically, they can occur in relatively young people in their 40′s and 50′s even with no prior warning signs. This is why it is important to assess and recognize the risk of CAD based on risk-factors such as hypercholesterolemia, hypertension, family history of CAD, smoking and diabetes. Often, being able to look at the health of one’s arteries can be life-saving such as with carotid IMT testing.
When heart muscle (myocardium) does not get adequate blood supply or oxygen, if suffers from myocardial ischemia. A heart attack can occur not only if heart muscle has all blood supply totally cut off by a blood clot, but also if severe myocardial ischemia lasts for too long. Either way, a heart attack is referred to as a myocardial infarction (MI). Over time, CAD can gradually weaken the heart muscle with recurrent myocardial ischemia or MI’s and contribute to heart failure (when the heart can’t pump blood well enough to the rest of the body) or arrhythmias (where there are changes in the normal beating rhyhtm of the heart).
Symptoms of CAD
- Chest pain (angina). While usually referred to as a “pain” in the chest, most commonly, people describe the sensation as a pressure or tightness in chest, as if a weight was put on the chest. When a coronary artery is at least 60 – 70 % blocked and stable, most commonly angina is brought on by physical activity or stress or emotional stress which leads to myocardial ischemia. In a stable state, it typically resolves within minutes after stopping the stressful activity. Often medications such as nitroglycerin or other anti-anginal medications are required to control the symptoms. People can have “angina” that spreads to other areas from the chest, such as the neck, back or arms or even have their discomfort starting in areas other than the chest. Angina tends to be more atypical in women than men. Some people have myocardial ischemia but no angina (“silent ischemia”) that can be picked up on stress tests.
- Shortness of breath. Some people have an “anginal equivalent” with a sensation of shortness of breath rather than chest discomfort. However, shortness of breath can occur in addition to angina, especially if the myocardial ischemia is causing enough heart muscle to not perform adequately leading to the heart not pumping enough blood to meet the body’s needs. Often people have extreme fatigue with exertion.
- Palpitations. If myocardial ischemia leads to arrhythmias, sometimes even just due to occasional extra heart beats coming from the main part of the heart muscle, people can have palpitations. They might also have general weakness or lightheadedness due to arrhythmias or the heart not pumping adequately
- Heart attack. Classically, signs and symptoms of a heart attack include more severe or “crushing” pressure in the chest and/or neck, shoulder or arm, sometimes accompanied by shortness of breath, sweating, nausea or lightneadedness. Just as with angina, women are more likely than men to experience less typical signs and symptoms such as jaw, upper abdominal or back discomfort, or nausea and lightheadedness, even without chest discomfort. Some heart attacks can occur without any obvious signs or symptoms. If you think you’re having a heart attack, immediately call 911.
Risk Factors for CAD
- Abnormal cholesterol (referred to as dyslipidemia, high cholesterol or hypercholesterolemia); particularly high levels of low density cholesterol (LDL-C or “bad” cholesterol), small and dense LDL particles even if the LDL level is normal, and low levels of high density cholesterol (HDL-C or “good” cholesterol).
- Hypertension or high blood pressure which can contribute to hardening and thickening of your arteries, especially when not adequately controlled.
- Diabetes is associated with an increased risk of coronary artery disease.
- Smoking. Nicotine constricts blood vessels and carbon monoxide candamage their inner lining, making them more susceptible to atherosclerosis. The incidence of heart attack in women who smoke 20 ciarettes or more a day is six times that of women who’ve never smoked. For men who smoke, the incidence is triple that of nonsmokers.
- Family history of CAD is associated with a higher risk of CAD, especially if a close relative developed it at an early age. Your risk is highest if your father or brother was diagnosed with CAD beforfe 55 years or your mother or a sister developed if before age 65 .
- Obesity. Excess weight typically worsens other risk factors
- Physical inactivity. Lack of exercise is also associated with a higher risk of CAD.
- Advancing age. Simply getting older increases your risk of damaged and narrowed arteries.
- Male sex (although female risk all but catches up to men within 10 years of menopause)
Non-classic and emerging risk factors for CAD
- Chronic inflammation (including elevated C-reactive protein or CRP levels).
- HIV (more and more being realized as possibly as strong a risk factor as diabetes)
- History of radiation therapy to the chest, as is used for certain types of cancer.
- High stress. Unrelieved stress in your life may directly contribute to damaging your arteries as well as worsen other risk factors for CAD.
- Sleep apnea. Drops in blood oxygen levels occuring during sleep increase blood pressure and straine the cardiovascular system, possibly leading to CAD.
- Elevated Lipoprotein (a). Also known as Lp(a).
- ECG (EKG or electrocardiogram), a simple 5 -minute test that can reveal evidence of a prior heart attack, myocardial ischemia or rhythm abnormalities.
- Echocardiogram, an ultrasound of the heart that, among other things, might show signs of a prior heart attack.
- Stress testing, including stress echo and myocardial perfusion imaging stress testing. These tests are an indirect way of determining if adequate blood flow is getting to the heart muscle during physical activity or stress. If signs of myocardial ischemia are seen, it strongly suggests blockages in the coronary arteries.
- Coronary calcium scans are special CT scans that can reveal signs of plaque (but not severity of blockage) in the coronary arteries. Considered a “screening” test and thus, often not covered by insurance although can be a very useful test in assessing a person’s risk of having a heart attack over time.
- Coronary angiogram, an invasive procedure requiring skinny, flexible plastic catheters or tubes (cardiac catheterization), be put through the skin into an artery (usually via the leg) that leads back to the heart. Under real-time x-ray video, contrast dye can be injected through the catheters and into coronary arteries to allow the arteries to be visualized directly. This can reveal if blockages are present and how severe they are and can allow interventions such as angioplasty or stents be performed to open up blockages. This is still considered the “gold standard” test to determine severity of CAD although sometimes still requires non-invasive tests as well to guide the best therapeutic options. Nowadays, it is mostly used in the setting of heart attacks, unstable or very severe symptoms or in patients whose symptoms cannot be adequately be controlled with medications and lifestyle changes.
- Non-invasive CT coronary angiogram, where contrast dye is injected into an IV and a CT scan is taken allowing visualization of all coronary arteries. Sometimes this is not quite accurate enough to determine exact severity of blockages (compared to an invasive coronary angiogram), but often is helpful at ruling in or out significant problems. Usually not covered by insurance (although often is covered by Medicare).
- CIMT (carotid IMT) testing, a simple, painless, non-invasive 5-minute test using ultrasound (and thus no radiation), to determine how healthy your arteries are and what future risk of heart attack or stroke you might have. Not covered by insurance but often a very important test in helping to risk stratify patients and help determine the level of aggressiveness need to modify risk factors.
- Heart-healthy lifestyle, including quitting smoking, eating a heart-healthy diet, exercising regularly, losing excess weight and reducing stress (or at least learning how to better cope with it). This is arguably just as important (if not more important) as medications and high-technology interventions.
- Statins and optimizing cholesterol levels. Decreasing low-density lipoprotein (LDL, or the “bad” cholesterol) decreases the primary substance that deposits in coronary arteries contributing to plaque build up. Statins in particular seem to have additional healing powers and beneficial effects on arteries as well which is why they are usually used in patients with CAD even if their cholesterol levels are normal.
- Treating high blood pressure. Some type of drugs used for hypertension such as angiotensin-convertin enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) might specifically help prevent progression of CAD and might reduce the risk of future heart attacks in those whom have already had an attack.
- Aspirin and other anti-platelet blood thinners. As heart attacks are due to platelets clumping in a coronary artery where plaque has ruptured, thinning the blood or making platelets weaker in their intended action reduces the risk of a heart attack. However, as it increases the risk of bleeding, if one has a bleeding disorder or high risk of bleeding, aspirin might not be appropriate for some people. Always discuss the pros and cons of taking aspirin with your doctor. Other anti-platelet blood thinners such as Plavix (clopidogrel), Effient (prasugrel) and Brillinta (ticagrelor) are sometimes used in addition to aspirin (or instead of it).
- Anti-anginal medications. In particular, beta-blockers slow your heart rate and dcerease your blood pressure which decreases your heart’s demand for oxygen. If you’ve had a heart attack, beta blockers reduce the risk of future attacks. Nitroglycerin tablets, sprays and patches can control angina by opening up coronary arteries and reducing the pressure inside the heart. Calcium channel blockers relax the muscles of the coronary artries and open the vessels increasing blood flow to the heart. They also reduce high blood pressure.
- Percutaneous coronary interventions (PCI or angioplasty or stents) can be lifesaving if done early in the course of a heart attack or at least reduce the amount of permanent damage to heart muscle and potential complications. An interventional cardiologists inserts a long, thin tube (catheter) up through an artery in the leg or arm and up into the coronary artery with the blockage. A skinny, very flexible wire is threaded up throught the catheter and coronary artery and through the blockage or narrowed area. A balloon is threaded over the wire, often nowadays with a stent on it. and the balloon is inflated, compressing the plaque against the artery wall and opening up the narrowing. Stents help prop and keep the artery open and often have a medications that is slowly released to help keep the artery open. In stable patients, if they continue to have symptoms from CAD not adequately controlled by medications, then a PCI might be indicated to help them feel better. While an important intervention for patients having a heart attack or whom are unstable and about to have a heart attack, PCI generally does not prevent heart attacks in stable patients.
- Coronary artery bypass surgery (CABG). A surgical procedure that has existed for over four decades (albeit with many technical enhancements and improvements) where a surgeon uses a blood vessel from another part of the body to bypass blockages or narrowings in the coronary arteries. Because this requires open-heart surgery, it most often is reserved for cases with multiple narrowed coronary arteries with other high-risk features not amenable to PCI.
- Alternative dietary supplements. Fish oil supplements (which contain omega-3 fatty acids) may offer benefit, but the evidence is strongest for eating fish, especially if part of a well-balanced heart-healthy diet. (Fatty fish, such as salmon, wild being better than farm-raised, herring and to a lesser extent, tuna, contain the most omega-3 fatty acids and therefore the most benefit). In addition, non-prescription fish oil supplements often might not be pure (and there is less regulation of the natriceutical industry than of the pharmaceutical or food industry) and most concerning is that the toxins in the sea tend to deposit in the fat of fish. This is not a concern with pharmaceutical grade or definitely pure fish oil supplements. Other sources of omega-3 fatty acids include flax and flaxseed oil, walnuts, canola oil, soybeans and soybean oil but all of these contain smaller amounts of omega-3 fatty acids than do fish and fish oil, and evidence for their benefit to heart health isn’t as strong. Other supplements may help reduce blood pressure or choleterol levels and include: Oat bran (found in non-instant oatmeal and whole oats); silostanol (found in oral supplements and some margarines, such as Benecol); beta-sitosterol (found in oral supplements and some margarines, such as Promis Activ); barley; artichoke; psyllium,; alpha-linoleic acid (ALA); garlic and cocoa.
While healthy lifestyle changes are the foundation of treating CAD, regular medical checkups to make sure the disease is stable and medications are appropriate and optimized, is critically important. In addition, some of the main risk factors for CAD — high cholesterol, high blood pressure and diabetes — have no symptoms in the early stages. Early detection and treatment can set the stage for a lifetime of optimal heart health.
Whether for primary or secondary prevention, to improve your heart health you can:
- Eat a diet rich in fruits, vegetables, whole grains and fish but avoid saturated fats and processed foods. Make sure the predominant fat used is from monounsaturated fats. For more information on heart-healthy diets, click here.
- Stay physically active
- Maintain a healthy weight
- Reduce and manage stress
- Absolutely quit smoking
- Control conditions such as high blood pressure, high cholesterol and diabetes.
For more on preventive cardiology, click here.
Written by and/or reviewed by Mark K. Urman, MD and Jeffrey F. Caren, MD
Last updated: 07/12/2013