Heart Disease: Recognizing and Reducing Risk Factors
The vast majority of people who develop coronary artery disease have at least one major risk factor. Although you can’t change some of them (namely, your age, gender, and genes), you can control most of them by making positive lifestyle choices like eating a healthy diet, exercising regularly, and not smoking. All of those habits will also help address other health problems (such as diabetes and high blood pressure) that raise your risk of heart disease.
There’s yet another range of issues that falls somewhere in between: psychological factors, which include stress, depression, anxiety, neuroticism, and anger. On one hand, it might be difficult to control many of the events in your life that cause stress or hardship. On the other hand, you do have a certain degree of control over how you respond to those stresses. The special section, “Hearts and minds: How stress and negative emotions affect the heart,” explores the latest findings on this topic.
What you can’t control: Age, gender, and genes
Some risk factors for coronary artery disease are unavoidable. But it’s good to be aware of them and to know that addressing factors you can control can still lower your risk.
Heart disease becomes more prevalent with age in both men and women (see Figure 3). More than four in five people who die from heart attacks are over age 65. In men, risk begins to mount beyond age 45, whereas women’s risk rises after age 55.
Figure 3: Heart disease: Men vs. women
By middle age, almost 40% of men and women have cardiovascular disease, which includes coronary artery disease, heart failure, stroke, and hypertension. By age 80, the percentage rises to about 80% in men and 87% in women.
Source: National Center for Health Statistics and National Heart, Lung, and Blood Institute.
Although heart disease remains the leading killer of both women and men in the United States, there are differences between the genders when it comes to symptoms and prognosis. Men are more likely than women to develop coronary artery disease, and usually at younger ages. Moreover, the average age for a first heart attack in men is 65; for women, it is 70.
Women also differ from men in terms of cardiac health outcomes. Although women tend to be better than men at describing medical symptoms and seeking help, women have a 50% greater chance of dying from heart disease than men do. At ages 40 and older, about 26% of women who’ve had heart attacks die within a year, compared with 19% of men. What’s more, women are almost twice as likely as men to have a second heart attack within six years of the first. Women are also more likely to die in the hospital after coronary artery bypass surgery or angioplasty.
What might explain these disparities? A leading theory is that women are more likely to die because they tend to develop heart disease and have heart attacks at a later age compared with men, and are thus more frail when their heart attacks occur. Women also are more likely than men to have other illnesses, such as diabetes, by the time they undergo heart surgery. Another problem is anatomy: women’s hearts tend to be smaller than men’s, making it more difficult for surgeons to stitch arteries together during surgery or keep them open after angioplasty. A condition called coronary microvascular disease (see “What is coronary microvascular disease?”) could be another reason.
Some research suggests that women with heart problems may not be diagnosed as early or treated as aggressively as men. For instance, women with heart attack symptoms are less likely than men to be admitted to the intensive care or coronary care unit and to get electrocardiograms, clot-busting drugs, or cardiac catheterization. After leaving the hospital, they are less likely to be directed to a cardiac rehabilitation program (or to finish one), or to get counseling about nutrition, exercise, and weight loss.
The classic symptoms of a heart attack were identified largely in studies of white, middle-aged men. But these symptoms do not always occur in women, which may contribute to delays in diagnosis and treatment. For instance, one study of heart attack symptoms reported that an astounding 43% of women who had heart attacks did not recall any type of chest pain, usually considered the hallmark symptom. Instead, the women reported shortness of breath, weakness, unusual fatigue, cold sweat, and dizziness.
What should you do to protect your heart if you’re a woman? Perhaps most important, focus on steps you can take to prevent heart disease, and take medications if necessary to lower blood pressure and cholesterol (see “Medications for heart disease”). Second, learn more about what types of symptoms indicate you may be having a heart attack (see Table 7).
Hormones were once considered a possible explanation for the gender differences seen in heart disease. But teasing out the effects of testosterone and estrogen and their relationship to heart disease risk has proven complicated. Men with low testosterone levels appear to have a higher risk of heart disease, type 2 diabetes, and other long-term conditions. But there’s no evidence that boosting testosterone levels (via injections, gels, or lozenges of the hormone) can lessen that risk. What’s more, athletes who abuse testosterone and other male hormones have a clearly higher risk for high blood pressure, heart attack, and stroke.
Estrogen raises HDL cholesterol and lowers LDL cholesterol. But when estrogen declines at menopause, typically around age 50, so do its protective effects, causing a sharp increase in the risk for heart disease. Women who have gone through menopause are two to three times as likely to develop heart disease as women the same age who are still menstruating. Yet, as two major studies showed, hormone replacement therapy not only does not prevent heart disease, it may actually increase heart disease risk in some cases.
Most women don’t realize that heart disease is the No. 1 killer of women in the United States, according to an American Heart Association survey. In 2007, heart disease claimed the lives of more than 190,000 women, compared with about 41,000 deaths from breast cancer and 70,000 from lung cancer.
Family history, race, and ethnicity
Coronary artery disease runs in families, and certain racial and ethnic groups are more at risk than others. Latinos, Asian Americans, and American Indians are less likely to have coronary artery disease than whites and blacks. Are certain families and ethnic groups more at risk because of shared environmental and lifestyle characteristics such as smoking, diet, inactivity, or psychological stress? Or does this situation reflect genetics, which may underlie risk factors such as high cholesterol, blood pressure, and blood sugar? The answer is both.
Family history. The genes you inherit are certainly important. Many studies have shown that people with a parent who developed coronary artery disease before age 55 face a much higher risk than others of developing heart disease themselves. Estimates of the magnitude vary, but this type of family history is clearly on par with other major risk factors such as high blood pressure and cholesterol.
However, it’s important to keep two things in mind. First, not every family history is equally worrisome; it takes a strong history (for example, a father or brother afflicted before age 55 or a mother or sister stricken before age 65) to increase your risk. Second, genetic research into heart disease remains in its infancy, and many questions remain, particularly about which genes are most important in making people susceptible to heart disease and how these genes interact with other genes and lifestyle factors to affect risk.
Many studies are now under way to better understand the genetics of heart disease. The hope is that genetic testing will one day enable doctors to identify people at high risk for heart problems and perhaps help them avoid those problems with preventive treatment. In the meantime, if you have a family history of heart disease, it’s vital to address risk factors such as high blood pressure and elevated cholesterol and adopt a heart-healthy lifestyle as soon as possible.
Race and ethnicity. Blacks are more likely to develop heart disease and to die from it than whites, Latinos, and Asian Americans. In fact, when adjusted for age, death rates from heart disease are 30% higher in black men than white men, and 40% higher in black women than in white women. One reason behind these trends may be the high rates of high blood pressure among blacks. Experts also believe that a number of other factors may explain the disparity, such as education and economic differences, both of which can affect access to appropriate medical care, and unique stressors such as discrimination. (For more on stress and heart disease, see the special section, “Hearts and minds: How stress and negative emotions affect the heart.”) As a result, despite advances in medical treatments for heart disease, life expectancy remains approximately five years higher in whites than in blacks.
What is coronary microvascular disease?
Unlike typical coronary artery disease, which affects the heart’s largest arteries, microvascular disease affects the heart’s smallest arteries. Instead of growing inside the artery, plaque limits blood flow by growing evenly around the artery, or bulging outward. In addition, these tiny arteries can spasm and tighten, preventing adequate blood flow. Standard tests such as a coronary angiogram don’t always detect microvascular disease, which is more likely to occur in women than men.
Lifestyle habits that raise your risk
Eating an unhealthy diet, not exercising, and smoking can all conspire to raise your risk of heart disease. The same factors increase your odds of developing high blood pressure and diabetes.
When it comes to heart disease risk, you are what you eat. As noted above, a poor diet contributes to elevated cholesterol and triglycerides, high blood pressure, diabetes, and obesity. A number of major studies provide compelling evidence that diet also affects the likelihood of progressing to full-blown coronary artery disease and having a heart attack. The Lyon Diet Heart Study, for instance, reported that people who regularly adhere to a Mediterranean-style diet are 50% to 70% less likely to have a heart attack, stroke, or other type of cardiovascular problem or to die from heart disease. This type of diet includes eating plenty of fruits, vegetables, beans, whole grains, and nuts; using olive oil and other types of unsaturated fats for cooking; eating more fish and poultry and less red meat; and drinking wine in moderation. Other research shows that consuming more omega-3 fats, found in certain fish, nuts, and other foods, as well as in supplements, may be particularly heart-healthy (see “Healthy fats”).
Just about everyone can benefit from a heart-healthy diet. Be aware, however, that while some foods, such as soy products and cereals, come with labels identifying them as “heart-healthy,” no one food will prevent or reverse heart disease. Instead, decades of research have provided the basis for some general guidelines (see “Eat healthy foods”) that, if followed, can go a long way toward preventing heart disease.
Only one in three American adults regularly engages in any kind of leisure-time physical activity. The reasons are many, but certainly the advent of labor-saving devices and the lure of television and the Internet are taking their toll — along with harried lives that leave little time for exercise. Yet it is clear that physical activity is a good investment of time when it comes to protecting your heart. Sedentary living roughly doubles the risk for coronary artery disease, making it as risky as smoking, high cholesterol, or high blood pressure.
More than 50 years of research shows that the people who are the most physically active are only half as likely to develop coronary artery disease as the most sedentary people. And the benefits accrue in a dose-response manner: the more physically active you are, the lower your risk for heart disease. What’s more, regular physical activity raises HDL cholesterol levels, reduces triglycerides, lowers blood pressure, burns body fat, and lowers blood sugar levels. When combined with weight loss, exercise can also lower LDL levels. It also helps alleviate mental stress, which can be a trigger for heart problems. Following a heart attack, an exercise-based rehabilitation program can reduce the likelihood of dying from heart disease by one-third. (For tips on how to add exercise to your life, see “Get active.”)
Tobacco use and exposure
Everyone knows that smoking is a major health hazard: it’s the leading preventable cause of death in the United States. But some people may be surprised to learn that smoking is not only a cause of cancer, but also one of the most significant risk factors for heart disease. People who smoke are two to four times as likely to die from heart disease as nonsmokers.
Passive exposure to other people’s smoke also puts you at risk. A report issued by the U.S. Surgeon General in 2006 warned that nonsmokers exposed to secondhand smoke at home or work increased their risk of developing heart disease by 25% to 30%.
In all, about one in three smoking-related deaths is from coronary artery disease. But quitting smoking can significantly reduce the risk. Within a year of quitting, smokers can cut their heart disease risk in half. In 15 years, the coronary artery disease risk for a former smoker is very close to that of a person who never smoked. One possible reason for this decrease in risk is that smoking probably contributes to blood vessel inflammation; removing that irritant should slow the inflammatory process. (For tips on how to kick the habit, see “Stop smoking.”)
Health conditions that raise your risk
The two most prevalent conditions linked to heart disease, diabetes and high blood pressure, are also more common among people who are overweight or obese. If you’re among the majority of Americans who are carrying extra pounds, losing weight is the most critical step toward resolving your risks for these common and potentially dangerous health problems.
Overweight and obesity
Because obesity is so closely linked to high blood pressure, unfavorable cholesterol levels, lack of exercise, and diabetes, scientists took a long time to figure out whether obesity itself is a cardiac risk factor. Experts now agree that it is. Excess weight increases your risk for heart disease independent of these other conditions.
There are two ways to estimate body fat. One is waist measurement. An increase in waist size is an indicator of increased body fat. As you grow older, you may find that your waist size increases even though you have not gained pounds. That’s because people tend to lose muscle mass and gain fat with age. Any increase in waist size is a signal that your percentage of body fat is increasing. In the past, experts thought that carrying most of your fat above the waist in your upper body (the “apple shape”) was more dangerous to the heart than fat stored lower in the body, in the hips and thighs (the “pear shape”). But evidence suggests that the location of excess weight doesn’t seem to make a difference — extra pounds harm the heart regardless of where they accumulate.
Body mass index (BMI), which takes both height and weight into consideration, provides another way to estimate body fat (go online to www.nhlbisupport.com/bmi for a calculator, or see Table 1). You should aim for a BMI of 19 to 24, the range that’s considered normal and poses minimal risk for heart disease and other health problems. A BMI of 25 to 29 is considered overweight (moderate risk), and a value of 30 or over is defined as obese (high risk).
A 2011 report in The Lancet pooled findings from 58 studies involving more than 220,000 people to better understand how to use body fat measurements to help assess heart disease risk. The investigators concluded that BMI, waist circumference, and waist-to-hip ratio (another way to gauge body size) were equal in terms of predicting heart disease risk. Given that it’s simpler to look up your BMI than to correctly measure your waist or hip circumference, it makes sense to focus on BMI. If you’re overweight or obese, it’s worth noting that losing even modest amounts — just 5% to 10% of your weight — can help lower blood pressure and improve cholesterol levels.
Table 1: Normal, overweight, or obese?
|The body mass index (BMI) is an index of weight by height. The definitions of normal, overweight, and obese were established after researchers examined the BMIs of millions of people and correlated them with rates of illness and death. These studies identified the normal BMI range as that associated with the lowest rates of illness and death.|
|Height||Body weight in pounds|
|Normal||Overweight||Class I obesity||Class II obesity||Class III obesity|
This chronic disorder is marked by high levels of sugar in the blood. Most of the 24 million Americans with this condition have type 2 diabetes, which occurs when the body becomes resistant to the effects of insulin (the hormone made by the pancreas that enables cells to draw sugar from the blood for energy) and does not produce enough insulin to overcome the resistance. Although the exact cause of type 2 diabetes isn’t clear, one thing is certain: excess body fat is the No. 1 risk factor. The other, far less common form of diabetes, type 1, is an autoimmune disorder that occurs when the immune system attacks the pancreas, destroying its insulin-producing cells.
The link between diabetes and heart disease is very strong. An adult diagnosed with diabetes has the same high cardiac risk as someone who has already had a heart attack. Everyone with diabetes, regardless of type or when it was diagnosed, has reason for concern. At least 65% of people with diabetes will die from some type of cardiovascular disease — a death rate that is two to four times that of the general population.
Many experts suspect that the long-term elevated blood sugar and low-grade inflammation seen in diabetes damage the coronary arteries, speeding the process of atherosclerosis. Heart attacks and other cardiovascular problems are not only more common in people with diabetes, but they occur earlier in life and are more likely to be fatal than in people without diabetes.
If you have diabetes, do your best to keep your cholesterol levels and blood pressure under control. People with diabetes should aim for LDL cholesterol levels of less than 100 milligrams per deciliter (mg/dL) and a blood pressure of less than 130/80 (ideally, less than 120/80; see next section for more information on blood pressure measurements). Also keep your blood sugar levels as close to normal as possible. However, tight blood sugar control doesn’t protect against heart attack as much as it helps to prevent other complications of diabetes, such as eye and kidney disease. Ask your doctor for a specific goal, as the target level depends on the blood test used to assess it.
Like everyone at risk, practice a healthy lifestyle: watch your weight, eat a heart-healthy diet, and exercise regularly (see “Lifestyle changes to protect your heart”). Talk to your doctor about taking a cholesterol-lowering statin if you can’t achieve your cholesterol goal through lifestyle changes, if you already have heart disease, or if you have one or more substantial risk factors for heart disease, such as being over age 55 or having elevated levels of C-reactive protein (see “Beyond blood lipids: Other biomarkers for heart disease”). You may also need one or more drugs to help you keep your blood pressure in check (see “Medications for heart disease”).
Yet another link between diabetes and cardiovascular disease should give you pause: diabetes can cause chronic kidney disease, which, in turn, can increase the risk of cardiovascular disease even more. Larger-than-normal amounts of a protein called albumin in the urine — a condition known as microalbuminuria — is an early sign of chronic kidney disease. Make sure your doctor orders a urine test for microalbumin at least once a year. And continue to do your part by controlling your blood sugar and blood pressure. Certain drugs used to treat blood pressure can help curb kidney damage.
High blood pressure
Your blood pressure reading has two parts. The first and higher number (systolic blood pressure) represents the pressure while the heart is beating and shows how hard the heart works to push blood through the arteries. The second and lower number (diastolic blood pressure) represents the pressure when the heart is relaxing and refilling with blood between beats and shows how forcefully arteries are being stretched most of the time.
The higher your blood pressure, the greater your risk of suffering a heart attack, heart failure, stroke, or kidney disease. Yet too many people ignore the risk posed by high blood pressure. Recognizing this fact, a federal report — the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7, for short) — urged Americans to take blood pressure more seriously and control it more aggressively.
Treating high blood pressure really pays off. Clinical trials have shown that treating hypertension reduces the incidence of stroke by 35% to 40%, the incidence of heart attack by 20% to 25%, and the incidence of heart failure by more than 50%.
Blood pressure goals. Given the evidence, the JNC7 guidelines not only defined normal (meaning “optimal”) blood pressure as anything under 120/80 millimeters of mercury (mm Hg), but also introduced a new category, prehypertension, to identify people who might prevent or at least slow the onset of hypertension by adopting a healthier lifestyle (see Table 2).
Table 2: Blood pressure guidelines
|The guidelines listed in this table are for adults ages 18 and older, based on the average of two or more seated blood pressure (BP) readings on each of two or more office visits.|
|Category||Systolic BP (mm Hg)||Diastolic BP (mm Hg)||Treatment recommendations|
|Normal||Less than 120||Less than 80||Lifestyle changes encouraged|
|Prehypertension||120–139||80–89||Lifestyle changes necessaryDrugs for compelling indications*|
|Stage 1 hypertension||140–159||90–99||Lifestyle changes necessaryThiazide diuretic for most people
May also consider other blood pressure drugs alone or in combination
Drugs for compelling indications*
|Stage 2 hypertension||160 or higher||100 or higher||Lifestyle changes necessaryTwo or more blood pressure drugs for most people
Drugs for compelling indications*
|*Compelling indications: diabetes, chronic kidney disease, previous heart attack, heart failure, previous stroke, high cardiac risk.Note: When systolic and diastolic pressures fall into different categories, physicians rate overall blood pressure by the higher category. For example, 150/85 mm Hg is classified as stage 1 hypertension, not prehypertension.
Source: Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC7), December 2003.
About 60% of American adults have high blood pressure (either prehypertension or hypertension). And data from the Framingham Heart Study indicate that people who are 55 years old and have normal blood pressure face a 90% chance of developing high blood pressure as they get older, unless they take preventive steps.
When to be tested. Because hypertension usually begins gradually between ages 20 and 50, all adults should have their blood pressure checked regularly. Blood pressure checks every two years might suffice for people with normal levels. But people with elevated blood pressure need more frequent measurement — once a year for those with prehypertension, and sometimes even more frequently in people with hypertension.
How low to go. For people with hypertension, JNC7 defines good control as getting your blood pressure under 140/90 mm Hg — but people with diabetes or chronic kidney disease should aim for an even lower level, below 130/80 mm Hg. The American Heart Association (AHA) recommends that people with coronary artery disease or other forms of atherosclerosis, or who are at high risk for heart disease, also lower their blood pressure below 130/80 mm Hg. However, this advice has been questioned, in light of research showing that blood pressure values below 130/80 did not result in fewer cardiovascular events.
To prevent or treat hypertension, the first step is to adopt healthier habits (see “Lifestyle changes to protect your heart”). Even with lifestyle changes, however, many people with hypertension also need medications to treat the disorder (see “Blood pressure medications”).
Unfavorable blood lipids
Many different forms of lipids, or fats, circulate through your bloodstream, including various forms of cholesterol and triglycerides. About one in five Americans has high total cholesterol, defined as 240 mg/dL or higher. But the chance of having a heart attack drops by 20% to 30% for each 10% drop in your total cholesterol level. The National Cholesterol Education Program (NCEP), part of the National Institutes of Health, has created guidelines that provide an easy way to set your cholesterol goal based on your risk for heart disease, and then to take steps to achieve your goal. The NCEP guidelines are periodically updated on the basis of new evidence. The 2004 guidelines are summarized in Table 3.
Table 3: LDL cholesterol treatment goals and options
|Use this table to get an overview of your goals and options for treatment. See Table 6 to determine your risk category.|
|Risk category||Your LDL cholesterol goal (mg/dL)||When to start lifestyle changes (mg/dL)||When to consider drug therapy (mg/dL)|
|Very high risk||below 70*||at or above 100||at or above 100 (optional: below 100*)|
|High risk||below 100 (optional: below 70*)||at or above 100||at or above 100 (optional: below 100*)|
|Moderately high risk||below 130 (optional: below 100*)||at or above 130||at or above 130 (optional: 100–129*)|
|Moderate risk||below 130||at or above 130||at or above 160|
|Low risk||below 160||at or above 160||at or above 190 (optional: 160–189*)|
|*Optional goal. Many experts anticipate revision of the NCEP guidelines and the possibility of lower LDL targets in some settings. If treatment brings your lipid levels substantially below the values listed above, you shouldn’t worry about being overtreated unless you’re having adverse side effects from the medication.|
Although total cholesterol levels are important, it’s even more important to look at levels of different types of cholesterol, particularly LDL and HDL. That is why the NCEP recommends that everyone age 20 or older undergo a fasting lipid profile test (also called a full lipid profile or lipoprotein analysis) every five years. This test measures not only total cholesterol, but also LDL, HDL, and triglyceride levels.
Total cholesterol. This number is the sum of cholesterol carried in all cholesterol-bearing particles in the blood, including HDL, LDL, and very-low-density lipoprotein (VLDL). Although the total cholesterol level closely parallels the LDL level in most people, there are enough exceptions to that rule to make it useful to test separately for LDL, HDL, and triglycerides. The NCEP guidelines advise aiming for a total cholesterol level below 200 mg/dL.
LDL. No specific cholesterol level guarantees that you will — or won’t — develop heart disease. However, LDL is clearly the bad element in terms of raising your risk for heart disease, so lowering elevated LDL should be the primary target of therapy. In making its 2004 recommendations, the NCEP cited data from clinical studies indicating that for every 1% reduction in LDL levels, there is a corresponding 1% drop in the chance of suffering a heart attack, stroke, or some other type of cardiac event. This is significant given that the proper combination of lifestyle changes and heart medications can help lower LDL levels by 30% to 40% in many people at risk for heart disease (and in some people, lower it even further), creating a corresponding drop in the risk for cardiac events.
So how low do you go? In a nutshell, if you have had a heart attack or are at very high risk of having one, the answer is lower than before, and probably as low as possible. Your particular LDL target depends on your cardiovascular health and your odds of having a heart attack in the next 10 years. Targets range from below 70 mg/dL for those at very high risk up to 160 mg/dL for people with the least overall risk (see Table 3). See “What’s my risk?” to determine your personal risk.
You can lower LDL levels by reducing the amount of saturated fat, trans fat, and cholesterol in your diet; eating more complex carbohydrates, such as fruits and vegetables; eating more fiber; reducing body fat; and exercising regularly (see “Lifestyle changes to protect your heart”). When these good habits aren’t sufficient to reach your cholesterol goal, cholesterol-lowering medications are recommended.
HDL. The more HDL in your bloodstream, the lower your chances of having a heart attack. Results from the Framingham Heart Study (a long-running, landmark study of factors contributing to heart disease) and elsewhere suggest that every one-point rise in HDL lowers the risk for heart attack by 2% to 3%. The NCEP guidelines consider levels of 60 mg/dL or above protective against heart disease, while levels of less than 40 mg/dL are regarded as too low and increase your risk. To boost your HDL, your best bets are to lose weight, eat well (paying particular attention to minimizing unhealthy fats and consuming more heart-healthy fats, as explained in “Healthy fats”), engage in more physical activity, stop smoking, and drink alcohol in moderation (no more than one drink a day for women and two for men). Certain medications can also help to raise HDL levels (see “Cholesterol medications”).
Ratio of total cholesterol to HDL. Some clinicians use the ratio of total cholesterol to HDL cholesterol to help identify people who need cholesterol-lowering therapy. As a general rule of thumb, the lower the ratio, the better. To determine your ratio, simply divide total cholesterol by HDL cholesterol. Reports from the Framingham Heart Study suggest that for men, a total cholesterol–to-HDL ratio of 5 signifies average heart disease risk; for women, average risk is signified by a ratio of 4.4.
Triglycerides. The main form of stored fat — both in the food we eat and in the body’s adipose (fat) tissue — is triglycerides. The chylomicron, the largest and least dense of the lipoprotein particles, carries most of the triglycerides in the bloodstream. In general, triglyceride levels have less impact on heart disease risk than LDL or HDL levels. However, when triglyceride levels are very high, risk for heart disease does increase. Often people with low HDL cholesterol levels also have high triglycerides, and this combination seems an especially important predictor of heart disease risk.
Table 4: Triglyceride levels
|Triglyceride level||Triglyceride category|
|Less than 150 mg/dL||Normal|
|150–199 mg/dL||Borderline high|
|500 mg/dL and above||Very high|
The NCEP guidelines define normal fasting triglyceride levels as below 150 mg/dL (see Table 4). High triglyceride levels can result from obesity, physical inactivity, tobacco exposure, alcohol abuse, uncontrolled diabetes, and even certain medications, as well as some genetic disorders. Often, triglycerides can be lowered using the same steps that help bring down LDL cholesterol: choosing healthful foods, exercising more often, losing weight, avoiding tobacco in all its forms, and, if necessary, taking medications.
Beyond blood lipids: Other biomarkers for heart disease
Biomarkers are substances that can be measured as possible indicators of the risk or progression of a specific health condition. For heart disease, several biomarkers have been studied for their potential to improve early diagnosis of heart disease. The two best known are C-reactive protein and homocysteine.
C-reactive protein (CRP) is a protein produced by the liver in response to infection, inflammation, or tissue injury anywhere in the body. For years, doctors have measured blood CRP levels to monitor diseases such as pneumonia, rheumatoid arthritis, and lupus. Mounting evidence that inflammation is an integral part of atherosclerosis led researchers to develop a new, more sensitive test to measure CRP, called the high-sensitivity CRP (hsCRP) or cardiac CRP (cCRP) test, which measures blood vessel inflammation.
Studies show that people with the highest CRP levels are about twice as likely to develop coronary artery disease and suffer a heart attack or other cardiac event as people with the lowest levels. As a result, CRP is now used along with other markers (such as cholesterol and blood pressure) to estimate cardiovascular risk. In 2008, a Harvard study showed that people without a history of heart disease who had average LDL cholesterol levels (less than 130 mg/dL) but elevated CRP (equal to or greater than 2 mg/L) who received a cholesterol-lowering statin medication had a 54% decrease in their risk of heart attacks, a 48% reduction in stroke risk, and a 43% decrease in venous blood clots compared with their counterparts who got a placebo pill.
Standards for using CRP in clinical practice are still evolving. For example, it is not yet clear what CRP target levels should be for healthy men and women of different racial and ethnic groups. For now, risk assessment is based on the following three levels of CRP:
The high-sensitivity CRP (hsCRP) test is recommended to ensure that you get the most accurate reading.
If you are already being treated for heart disease or are considered at high risk for cardiovascular disease (greater than 20% in the next 10 years, based on the calculations in Table 6 or an online risk calculator), a CRP test is not necessary. The results won’t change how you and your doctor manage your condition.
If you have a moderate risk of heart attack (10% to 20% in the next 10 years), an hsCRP test might help to more accurately place you in a high- or low-risk category. Studies indicate that people at moderate risk based on the conventional risk factors might move into the high-risk category if they also have elevated CRP. Such people might need more aggressive treatment to prevent a heart attack. In particular, your doctor may recommend a lower LDL goal — under 100 mg/dL rather than under 130 mg/dL.
If your cholesterol levels are fine but you have other risk factors (such as diabetes, high blood pressure, or a family history of heart disease), ask your doctor whether an hsCRP test would help to better assess your risk and decide how to reduce it. Think of the results as a “tiebreaker” to help you decide whether to take medications, if you’re on the fence about doing so.
Homocysteine. Starting in the mid-1980s, numerous studies noted a link between high blood levels of homocysteine (an amino acid found in everyone’s blood) and an increased risk of cardiovascular disease. Research also reveals that many people with high homocysteine levels are deficient in certain B vitamins: folic acid, B6, and B12. Supplements of these vitamins can reduce homocysteine levels within weeks.
But here’s the rub: lowering homocysteine levels does not appear to benefit people with normal homocysteine levels who already have heart disease. Two large studies found that B vitamin treatment in heart disease patients did not reduce the risk of heart attacks or other forms of cardiovascular disease, even though homocysteine levels in patients taking B vitamins dropped by 27%. The bottom line: while it’s still a good idea to get plenty of B vitamins in your diet (fruits and vegetables — especially dark leafy greens — are good sources) for overall health, there’s no reason to take B vitamin supplements to stave off heart disease.