• Sudden cardiac arrest deadly but preventable

    July 2008  

    The recent, untimely death from sudden cardiac arrest (SCA) of popular newsman Tim Russert serves as a reminder that heart disease can be silent and that people should strive to reduce known risk factors. SCA, also called sudden cardiac death, is responsible for approximately half of the deaths due to heart disease in the United States, killing nearly 850 people a day. It occurs when a sudden arrhythmia causes the heart to stop beating.

    SCA differs from a heart attack, in which blood flow is blocked but the heart usually continues to beat. However, SCA can occur after a heart attack disrupts the heart’s electrical system and causes arrhythmia. This is what happened to Russert: He experienced a heart attack when plaque ruptured and blocked an artery, disrupting his heart’s electrical impulses and leading to SCA. Such events occur after approximately 15 percent of all heart attacks.


    “The best way to reduce the incidence of SCA is to control the risk factors for coronary disease.”


    The 58-year-old Russert exercised regularly, took medication to control his blood pressure and cholesterol, and had recently been given a clean bill of health after a medical examination. Unfortunately, all of this apparently was not enough to overcome the effect of his risk factors for heart disease: He had diabetes and coronary artery disease and was significantly overweight. Additionally, he was a member of the group among whom SCA is most common: men age 58 to 62.

    Who is at risk

    In an article appearing in the May/June 2008 issue of Progress in Cardiovascular Diseases, Henry Greenberg, MD, identifies several factors that can cause the electrical problems that may lead to SCA:

    • Cardiomyopathies and congestive heart failure;
    • Genetic abnormalities such as long QT syndrome, a rare hereditary disorder of the heart’s electrical rhythm; and
    • Coronary artery disease leading to myocardial infarctions.

    Patients in the first category may be fitted with an implantable defibrillator to correct abnormalities of the heart’s electrical system and protect them from SCA. For example, Vice President Dick Cheney, who has a cardiomyopathy resulting from several heart attacks, has an implantable defibrillator.

    For people like Russert who have coronary artery disease, Greenberg states, "The best and most effective approach will be to control coronary risk factors through medical and public health initiatives. By slowing the advance of coronary atherosclerosis, by reducing the frequency of acute coronary events, and by limiting the tissue loss from myocardial infarction," he says, we can reduce the incidence of SCA.

    Atherosclerosis

    Atherosclerosis is a slow, progressive disease that begins in childhood. Many scientists believe that atherosclerosis begins when the innermost layer of an artery, the epithelium, is damaged. Causes of epithelial damage include the following:

    • Elevated levels of cholesterol and triglyceride in the blood.
    • High blood pressure.
    • Tobacco smoke.
    • Diabetes.

    When the arterial wall is damaged, platelets clump along the wall to repair the damage, thereby creating inflammation. Plaque may then accumulate at such sites, and it is the rupture of plaque that triggers a heart attack or stroke.

    Tobacco smoke greatly worsens atherosclerosis and speeds its growth in the coronary arteries, the aorta and the arteries in the legs.

    SCA-associated mortality

    According to the American Heart Association, the survival rate for persons who experience SCA outside a hospital is approximately 6 percent. Without immediate, effective CPR, the chance of surviving decreases by 7 to 10 percent per minute. But CPR alone is not enough. Rapid treatment with a defibrillator, which sends an electrical shock to the heart, is necessary to stop the abnormal heart rhythm and restore a normal rhythm. Automated external defibrillators (AEDs), often found in public places such as airports and office buildings, can save the life of a person experiencing SCA. And the operation of these devices is simple enough to allow their use by a person who is not a medical professional.

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Page last updated: 5/19/2014 1:27:56 PM
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    What the news means for you

    Prevention is key

    Charles L. Campbell, MD
    Cardiologist

    Wright, Heather, MD We have traditionally used measures such as cholesterol levels and blood pressure to determine which patients may be at high risk of myocardial infarction and sudden cardiac arrest.


    “The survival rate for persons who experience SCA outside a hospital is 6 percent.” 


    The question raised by Tim Russert’s death is whether we can find a better way of making this determination. Certain emerging laboratory tests hold promise. One of these tests measures the serum concentration of the high-sensitivity C-reactive protein (hs-CRP), a marker of infection and inflammation. Another test detects oxidized phospholipids in the blood; these lipids play an important role in coronary blockages.

    However, these and other new tests need further study. It’s not clear at this point what doctors should do if, for example, they find that a patient has a high concentration of CRP but a low concentration of cholesterol and a normal blood pressure.

    Echocardiography can be used to evaluate the structure of the heart, but we don’t typically perform this study when the patient isn’t experiencing symptoms.

    Additionally, it’s very possible that Russert had no severe blockage in an artery before his sudden cardiac arrest. Even if a CT scan had detected a blockage, the blockage might not have appeared severe. When plaque ruptures, it can rapidly enlarge until the artery is occluded and a cardiac event occurs.

    Control risk factors

    The most important thing for people to do is to get control of their risk factors for coronary artery disease. Too many people in the state of Kentucky smoke, too many have high cholesterol levels, and too many are obese. The prevalence of these risk factors leaves many in Kentucky at higher risk of sudden cardiac arrest than Russert, who apparently had taken steps to reduce his risks.

    The process of atherosclerosis, the disease that leads to heart attacks and sudden cardiac death, begins when persons are in their teens or even earlier. Most older Americans eating a typical American diet have some degree of atherosclerosis. Our diet is our worst enemy. We eat too many processed foods and too few fruits and vegetables.

    Exercise is also vitally important because it can help reduce the effect of some of these risk factors. It also has many important fringe benefits, such as improved well-being.

    Unfortunately, I can examine 100 people with the same risk factors and still not be able to tell who will be the first to experience SCA. However, there are usually warning signs. Russert probably had symptoms but ignored them.

    You and your doctor can probably identify most of the factors that are associated with a high risk of heart disease and SCA: age, blood pressure and family history. If you increase your activity level, lose weight, stop smoking and reduce your cholesterol levels, you will have done much to reduce your risk of heart attack and sudden cardiac death.

    Symptoms

    To increase your chances of surviving SCA, you must be aware of the symptoms of a heart attack and seek immediate care if you experience them. Approximately 20 percent of people who have a heart attack die at home most because of SCA. Those who come to the hospital while experiencing a heart attack have an 85 to 90 percent chance of surviving. If they’re already in shock upon arrival at the hospital, their chance of surviving drops to 20 to 50 percent.


    “The most important thing for people to do is to get control of their risk factors for coronary heart disease.” 


    The classic symptoms of a heart attack are chest discomfort and pain radiating to the neck and jaw, with associated shortness of breath, lightheadedness and sweating. Sometimes a person will have only one of these symptoms, but if this is a new problem and exercise makes it worse, you need to see a doctor.

    Compared with men, women usually have fewer descriptive symptoms and are older when they experience a heart attack. But just as for men, it is important for women to act promptly when symptoms occur.

    Promising research

    At the Gill Heart Institute, several studies related to SCA are ongoing, including studies and on medications that reduce the risk of heart attack. Additionally, researchers are investigating methods of repairing the heart and preventing SCA.

    Nationally, numerous ongoing research trials are aimed at reducing the risk of a heart attack and sudden cardiac death. One of these, the JUPITER trial (Justification for the Use of Statins in Primary Prevention: an Intervention Trial Evaluating Rosuvastatin), is investigating whether high-intensity statin therapy should be given to patients who have low LDL cholesterol concentrations but elevated CRP concentrations. The results of this study should be available soon.

    Dr. Campbell is director of the UK Coronary Care Unit, assistant professor of medicine (cardiology) in the UK College of Medicine and on staff at the UK Gill Heart Institute.

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