Thursday, February 22, 2018

Risk Factors for Heart Disease

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Category: Heart Disease

The stereotype is that heart disease—mostly heart attack—is a man’s disease. Actually, it’s the leading cause of death for both men and women. Heart attack, medically known as myocardial infarction or MI, is almost as lethal as all cancers combined. Heart attacks strike Americans once every 29 seconds, and kill once a minute. The American Heart Association estimates that heart disease costs the nation some $274 billion a year—more than $1,000 per person every year.

A heart attack is the culmination of a process that starts in childhood. It begins when something injures the lining of the arteries that supply blood to your heart (coronary arteries). Quite often that something is a highly reactive oxygen molecule (free radical) that causes “oxidative damage.” Your immune system sends white blood cells (monocytes) to repair the damage. But in doing so, they cause inflammation and create scar tissue that attracts circulating cholesterol, which collects and begins to form deposits (plaques).

Over several decades, your plaques grow, and slowly narrow your arteries, a process called “atherosclerosis.” Plaques are like acne pimples. If one pops, its contents spill into your bloodstream and may completely plug a section of coronary artery that’s already severely narrowed by other plaques. Once blocked, that artery cannot deliver food and oxygen to part of your heart, and cells in the affected area die. That’s a heart attack.

Risk Factors for Heart Disease

Age. About 85 percent of people who die of heart disease are over 65. But if you suffer a heart attack before 65, you’re much more likely to die from it.

Heredity. Heart disease tends to run in families.

Gender. In every age group, men have more heart attacks than women. Before menopause, women enjoy considerable protection, thanks to the female sex hormone, estrogen. It largely prevents the internal blood clots that trigger heart attacks. But if you’re a woman, menopause raises your heart attack risk considerably because you have less circulating estrogen, says Martha Hill, R.N., Ph.D., a professor of nursing, medicine, and public health at the Johns Hopkins University School of Medicine and past president of the American Heart Association. Compared with men, older women who have heart attacks are less likely to survive them.

Smoking. Smoking is a major source of oxidative damage. According to a report by the U.S. Surgeon General, “Cigarette smoking should be considered the most important risk factor for coronary heart disease.” Compared with nonsmokers, smokers have more than twice the risk of heart attack, and are more likely to die from them. Passive smoking also raises heart-disease risk. As many as 37,000 heart-disease deaths a year may be caused by exposure to second-hand smoke from living with smokers.

High cholesterol. High cholesterol, the waxy compound found in meats and whole-milk dairy items, is a major risk factor for heart disease. A level below 180 milligrams per deciliter of blood (mg/dl) means a very low risk of heart attack. Cholesterol from 180 to 200 suggests modest risk. In the range of 200 to 239, you have moderate risk. And level of 240 or higher means substantial risk.

High-fat diet. A high-fat diet goes hand in hand with high cholesterol because Americans get most of their fat from meats and dairy items, which are also our primary sources of cholesterol. A high-fat, high-cholesterol diet pumps lots of free radicals into your bloodstream, which start damaging your ateries in childhood. The Bogalusa (Louisiana) Heart Study has followed the health of 14,000 children for several decades, and has autopsied those who died young (mostly from accidents, homicide, and suicide). Among those who died before age 15, about 20 percent already had atherosclerotic plaques in their arteries. By age 26, the figure was 60 percent.

High blood pressure (hypertension). Two numbers express your blood pressure: Doctors consider 120/80 mmHg (millimeters of mercury) normal, and 140/90 high. If you have high blood pressure, for every 1 mmHg you lower that second number in your blood pressure (diastolic pressure), your risk of heart attack drops 2 to 3 percent. In addition to substantially raising risk of heart attack, hypertension is also the leading risk factor for stroke.

Obesity. A few extra pounds aren’t so bad, but obesity—being more than 20 percent heavier than the recommended weight for your height and build—significantly increases your heart attack risk, especially if you don’t exercise regularly.

Diabetes. Diabetes injures your arteries, spurring atherosclerosis. Compared with the general population, diabetics have three times the risk of heart disese.

Lack of exercise. Couch potatoes often wind up with weak hearts, high cholesterol and blood pressure, and obesity and diabetes—all risk factors for heart disease.

High trigylcerides. Triglycerides are blood fats. High levels typically go hand-in-hand with high cholesterol. But even without very high cholesterol, high triglycerides (above 200 mg/dl) constricts your arteries and thickens your blood, making it more likely to form the clots that trigger heart attack.

Emotional stress. “Compared with people who are easy going,” Dr. Hill says. “time-pressured, driven, hostile, Type-A workaholics are at much higher risk of heart attack” (see Sidebar: “Stress, Emotions, and Heart Disease”). Emotional stress releases hormones into your blood that increase your heart rate, deplete magnesium, boost your cholesterol and triglycerides, and increase your risk of the internal blood clots that trigger heart attack.

Social isolation. Who has lots of friends? Mellow, easy-going folks. Who becomes socially isolated? Time-pressured, driven, hostile, Type-A workaholics. No wonder that many studies consistently show that social isolation is a risk factor for heart disease.

High homocysteine. Homocysteine (HOE-moe-SIS-teen) is an amino acid derived from methionine, another amino acid that abounds in animal foods. Vitamins B6, B12 and folic acid break it down for excretion. But if you don’t get enough of these vitamins, you wind up with a high homocysteine level, which greatly accelerates atherosclerosis and increases your risk of the internal blood clots that trigger heart attack.

How hazardous is high homocysteine? Irish researchers studied homecysteine levels in 750 heart-disease sufferers and 800 healthy controls. Compared with those who had low-to-moderate homocysteine levels, those with the highest levels were more than twice as likely to suffer heart attack. That makes high homcysteine about as bad as smoking. Speaking of smoking, cigarettes raise your homocysteine level. So do menopause and lack of exercise. In a study of 14,000 male doctors, Harvard researchers discovered that compared with those who had the lowest homocysteine levels, the physicians with the highest levels had three time the heart-attack risk.

Certain infections. Floss or die: That’s what some experts are saying since chronic gum disease, a bacterial infection, was shown to increase risk of heart attack. Other germs linked to heart disease are Cytomegalovirus and especially Chlamydia pneumoniae, a bacteria that causes respiratory infections. In one study, 90 percent of heart attack sufferers showed evidence of C. pneumoniae infection, but among matched controls without heart disesae, the figure was just 25 percent. C. pneumoniae infection also appears to play a role in heart-attack survival. Sandeep Gupta, M.D., and British researchers at St. George’s Hospital Medical School in London followed 213 male survivors for 18 months. Only 7 percent of the men who showed no evidence of infection had second heart attacks. But among those who were infected, the figure was 28 percent.

The more risk factors you have, the greater your chances of having a heart attack. For example, a middle-aged male smoker has about a 5 percent chance of suffering a heart attack within eight years. The same smoker who also has high cholesterol and blood pressure has a 10 percent chance—double the risk.

Some risk factors can’t be changed. “We’re all stuck with our age, gender, and heredity,” Dr. Hill explains. “But it’s never too late to work on risk factors that can be changed. Even if you’ve already had a heart attack, risk-factor reduction can prevent another one.” And as Dean Ornish has shown, reducing your risk factors with a comprehensive program of complementary therapies can actually reverses heart disease.

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