These heart attack risk factors can be controlled—or, even better, avoided or eliminated altogether.
Obesity
Every year, more and more Americans are classified as overweight or obese. According to the latest statistics, about 67% of adult Americans are overweight, including about 34% who are obese. Overweight or obese men and women have an increased risk of heart attacks and a greater likelihood of developing risk factors.
Body Mass Index (BMI)
Guidelines issued jointly by the National Heart, Lung, and Blood Institute and the National Institute of Diabetes and Digestive and Kidney Diseases recommend using body mass index (BMI)—a measurement of body weight in relation to height—to determine whether you are overweight or obese.
BMI is calculated by multiplying your weight in pounds by 703, then dividing the result by the square of your height in inches. For example, if you weigh 190 lbs and are 5 feet 10 inches tall, multiply 190 × 703 (which equals 133,570). Then divide this number by 70 inches squared, or 4,900 (133,570 ÷ 4,900 = 27.3). The result: Your BMI is 27.3. You can also use the online BMI calculator at www.nhlbisupport.com/bmi.
Overweight is defined as a BMI of 25 to 29.9; obesity, as a BMI of 30 and over. As BMI rises, blood pressure and triglyceride levels rise and HDL cholesterol levels drop. These adverse changes in blood pressure and lipid levels increase your risk of a heart attack. In addition, an analysis of 21 studies found that a BMI greater than 25 is a risk factor for a heart attack, independent of blood pressure and cholesterol levels.
Waist Circumference
How excess weight is distributed on your body is also important in determining heart attack risk. Research now shows that extra weight around your middle (called abdominal obesity) is particularly dangerous for your heart because it causes insulin resistance (the reduced ability to respond to insulin, a hormone that regulates blood glucose levels). Insulin resistance can lead to diabetes, high triglyceride and low HDL cholesterol levels, hypertension, and an increased risk of a heart attack.
One way to detect abdominal obesity is to measure your waist circumference. A waist circumference of greater than 40 inches in men or greater than 35 inches in women indicates abdominal obesity.
Diabetes
People with diabetes (fasting blood glucose level of 126 mg/dL or greater) are two to four times more likely to have a heart attack than people without diabetes. This higher risk is especially true for women. One reason why people with diabetes are at increased risk for a heart attack is they are more likely to have elevated triglyceride and low HDL cholesterol levels, high blood pressure, and obesity. Also, diabetes itself contributes to heart attacks. For example, young women with diabetes lose the protection that other pre-menopausal women have against heart attacks. In fact, women with diabetes have the same frequency of heart attacks as men of the same age who do not have diabetes.
People with prediabetes also have an increased chance of heart attacks. They have fasting blood glucose levels that are higher than normal (100 to 125 mg/dL) but not quite in the diabetes range.
Careful control of blood glucose levels with diet, exercise, and medication (if necessary) may reduce heart attack risk in people with diabetes or prediabetes. However, these measures do not completely eliminate the increased risk. Therefore, if you have diabetes or prediabetes, it is important to aggressively control any other risk factors for a heart attack that you might have.
The Metabolic Syndrome
A collection of health characteristics called the metabolic syndrome raises the risk of having a heart attack or stroke or developing diabetes. In an analysis of 37 studies, the risk of a heart attack or dying of cardiovascular disease was 78% higher for people with the metabolic syndrome than it was for those without the syndrome. Women with the metabolic syndrome were particularly at risk, having nearly three times the risk of heart attack or death than women without the syndrome.
Doctors diagnose the metabolic syndrome when someone has at least three of the following five findings:
The metabolic syndrome affects about 76 million people age 20 and older. Virtually all of them have insulin resistance, a decreased ability of the body’s tissues to respond to insulin, a hormone that enables cells to take up glucose from the blood for use as a source of energy. In fact, insulin resistance triggers many of the characteristics of the metabolic syndrome.
Treatment of the metabolic syndrome involves lifestyle measures such as weight loss, exercise, a fiber-rich diet, and smoking cessation. Medications to improve lipid levels, lower blood pressure, and control blood glucose also may be needed.
Physical Inactivity
Physical inactivity is an important risk factor for a heart attack. The American Heart Association recommends at least 30 minutes of moderate-intensity exercise (for example, brisk walking) five days a week. Exercise not only reduces your risk of a heart attack but also helps to control body weight, lower blood pressure, reduce the risk of diabetes, and improve triglyceride levels.
C-reactive protein (CRP)
The liver produces CRP when inflammation occurs anywhere in the body—including in the walls of the arteries. People with even small elevations of CRP have an increased risk of heart attacks regardless of their age, gender, general health, or other risk factors. In fact, elevated CRP levels (more than 2 to 3 mg/L) are found in up to half of all people who have a heart attack. The combination of an elevated LDL cholesterol level and a high CRP level increases the chances of a heart attack several-fold. One study of nearly 4,000 adults with stable coronary heart disease found that those with CRP levels of more than 3 mg/L were 52% more likely than those with CRP readings of less than 1 mg/L to suffer a heart attack or stroke or die of cardiovascular disease over a five-year period.
Physical activity, weight loss, quitting smoking, and statins all help to reduce levels of CRP. In one study, individuals who had a heart attack were less likely to have another one if their CRP levels were lowered while taking a statin. Researchers have yet to prove that lowering CRP prevents a first heart attack. What’s more, other heart attack risk factors such as elevated blood glucose and triglyceride levels and increased abdominal fat are associated with an elevated CRP.
Homocysteine
High blood levels of homocysteine are associated with an increased risk of heart attacks, strokes, and peripheral arterial disease. In one study, individuals with the highest homocysteine levels had about a threefold greater risk of a heart attack than those with lower levels. Doctors are uncertain how homocysteine affects the arteries, but high levels may promote atherosclerosis by damaging the cells that line the artery walls and promoting the buildup of plaques. Homocysteine may also stimulate blood clotting.
Levels of homocysteine can be reduced with folic acid supplements, but several large studies show that these supplements do not reduce heart attack risk.
Stress
Much research shows a relationship between mental stress and a risk of heart attacks. During times of stress, the body releases hormones, such as adrenaline (epinephrine), that speed heart rate, raise blood pressure, and may cause spasms (constrictions) of the coronary arteries. Nonetheless, stress is not considered a direct cause of heart attacks. Instead, it is a possible contributing factor.
Depression
A number of studies link depression with heart attacks, although doctors are not sure exactly how depression might increase the risk. One possibility is that people with depression are less likely to make efforts to control other risk factors—for example, quitting smoking, eating a healthy diet, exercising, and taking cholesterol or blood pressure medication. Another possibility is that depression causes changes in the body, including a rapid heart rate, high blood pressure, abnormal heart rhythms, faster blood clotting, and higher insulin and cholesterol levels, which increase the risk of heart attacks.
Treatment options for depression include cognitive-behavioral therapy, antidepressant drugs such as selective serotonin reuptake inhibitors (SSRIs), and physical activity. In fact, studies show that treating depression in people who have had a heart attack decreases their risk of a second attack.
