My husband's heart attack gave no warning. He was trim, felt good and exercised regularly. But in the follow-up care after his bypass surgery, he learned that his whole way of life must change. It was like dreaming you're in calculus III after barely squeaking through geometry - terms like HDL, LDL, mg/dl, triglycerides and cholesterol/saturated fats leaped at him and it was a life and death matter for him to learn them.

His typical on-the-move diet of bacon and eggs for breakfast, cheeseburger and french fries for lunch and a dinner of steak and baked potato with sour cream was suddenly a cholesterol-laden menu guaranteed to plug his new arteries.Heart and circulatory disease is the nation's major cause of death and will kill nearly 1 million Americans this year. It is believed that one in four Americans have high blood cholesterol levels and should take dietary action to reduce the level.

The American Heart Association estimates that about 350,000 heart attack victims will die this year before reaching a hospital because the average victim waits three hours before seeking help. When Americans know so little about heart disease that one-third of the victims of a heart attack don't even realize they've had one, how can the survivors expect to understand the complex dietary and lifestyle changes needed?

Rebecca A. Gould, Ph.D., R.D., is an assistant professor at the University of Utah's Division of Foods & Nutrition, and helped prepare "Getting Started" a series of pamphlets for the American Heart Association, Utah Affiliate. These concise and easy-to-read guides for low-cholesterol, low-fat eating are available to the public at no charge from the American Heart Association, Utah Affiliate, 645 E. Fourth South, Salt Lake City, UT 84102 (phone: 322-5601). Also available are pamphlets explaining heart disease, losing weight, informational grocery guides and cholesterol lowering strategies.

One fact sheet distributed by the Utah Heart Association explains that cholesterol is an odorless, white, powdery substance that is found in all foods of animal origin. It is used in our bodies to make cell walls and hormones and various other functions. It is not necessary for people to consume cholesterol; the liver can manufacture enough for the body's needs.

Because cholesterol will not mix with water, the liver "wraps" it in protein to carry it in the blood. The combination of cholesterol and protein is called lipoprotein (literally "fatty protein") and can be low density lipoprotein (LDL) and high density lipoprotein (HDL). Low density lipoproteins contain the greatest percentage of cholesterol and are thought to be responsible for depositing cholesterol in the artery walls. So the LDL's are known as "bad."

HDL's contain the greatest amount of protein and the smallest amount of cholesterol. They are believed to take cholesterol away from the cells and transport it back to the liver for processing or removal. Wom-en generally have higher quantities of this "good" carrier, which may explain in part why they have fewer heart attacks than men.

Higher levels of HDL are found in people who exercise regularly, don't smoke and maintain a normal weight.

When your cholesterol level is checked, a small sample of blood is taken to be tested in a laboratory. The cholesterol level is measured as milligrams per deciliter or "mg/dl." The average level for adults in the U.S. is 215 mg/dl.

Martha McMurry, head research nutritionist in clinical research at the University of Utah Health Sciences Center, explained the triglyceride readings obtained from a full blood work-up. "Triglycerides are another fat in the blood and are found in oils, margarine and butter. Most fat is triglyceride but a high triglyceride reading may be related to heart disease or may not. Our bodies store some fat in our fat tissue and also carry it in the blood so it can be used for energy. A high triglyceride level that is associated with high cholesterol and heart disease, responds to weight loss very well. A 200 or less count is a normal triglyceride level," she said.

Last October, the National Heart, Lung & Blood Institute of the National Institutes for Health lowered the cholesterol safety level from what was originally thought safe. The total blood cholesterol levels for males and females over 20 are classified as follows:

* under 200 mg/dl - desirable

* 200-239 mg/dl - borderline-high

* 240 mg/dl and above - high

In a recent study of men who had cholesterol blood levels of at least 265 mg/dl, half the group was given a drug to reduce cholesterol along with a cholesterol-lowering diet. The other half of the men were only on the diet. After 7 years, both groups of men had lower cholesterol levels, but the men on the diet and drug had lowered their levels more. In assessing the trial results, scientists determined that each 1 percent reduction in blood cholesterol produced a 2 percent reduction in the number of heart attacks. Men who had cut their cholesterol by 25 percent reduced their risk of heart attack by half.

Of the four major lipid-lowering drugs (known as antihyperlipidemics) the most popular is clofibrate (trade name Atromid-S). Other drugs include cholestyramine (Questran), colestipol (Colestid) niacin (Nicotinic Acid), neomycin and probucol (Lorelco). Side effects have been noted for these drugs but they can cut cholesterol levels by as much as 20 to 30 percent. An effective new drug, Lovastatin, is now being prescribed but possible side effects have not been established.

One confusing problem with heart disease dietary treatment is that a food product can be marked "no cholesterol" and yet contain saturated fats that will cause the liver to produce more LDL's - the carriers that deposit cholesterol in the arteries. So you can bypass direct consumption of cholesterol only to end up with saturated fats that will, in fact, increase your body's production of cholesterol. Saturated fat is found mostly in animal products and some vegetable oils (cocoa fat, chocolate and shortenings such as palm oil, palm kernel oil or coconut oil).

So the consumer must become the consummate label reader. Volume III of the Utah Heart Association's pamphlet "Getting Started" outlines the "how-to" of using labels to spot fat. A free copy of "Consumer's Guide to Food Labels" can also be ordered from Consumer Information Center, P.O. Box 100, Pueblo CO, 81002.

Dr. Robert Wray, cardiologist and director of Heart Catheter Laboratories at the University of Utah Hospital, sees heart patients when they have already developed deposits of plaque, hardened deposits of fat and cholesterol. While a new laser surgery is being tested that blasts plaque from blocked blood vessels, the conventional methods for dealing with life-threatening blockages are diet and drug treatments, bypass surgery: where a new route is created to the heart bypassing the clogged artery and when the heart is severely damaged: heart transplants.

Wray spelled out the profile of heart disease, "When a patient smokes, is overweight, has a high cholesterol level and gets little exercise, he is at increased risk for a heart attack."

The National Heart, Lung and Blood Institute has these suggestions for cutting down on cholesterol and saturated fat:

* Choose more vegetables, fruits, cereal grains and starches

* Choose fish, poultry and lean cuts of meat and serve moderate portions

* Trim fat from meats and skin from chicken before cooking

* Eat less or avoid organ meats such as liver, brain and kidney

* Eat less commercial baked goods made with lard, coconut oil, palm oil or shortening.

* Eat less sausage, bacon and processed luncheon meats

* Use skim or low-fat milk

* Choose low-fat cheeses

* Eat less cream, ice cream and butter

* Use low-fat yogurt

* Eat less food fried in animal fats or shortening

* Eat fewer eggs, or eat fewer egg yolks.

It is really not difficult to start trimming fat, removing the skin from chicken, broiling instead of frying and using two egg whites in place of one egg in baking recipes. Instead of baking with butter, use a non-cholesterol, low-in-saturated-fat margarine. Eating 3 ounces of oatmeal or oat bran each day has been found to be as beneficial as some of the cholesterol lowering drugs. Explained Martha McMurry, "It's the oat bran in oatmeal that is so beneficial and our best guess is that it binds cholesterol so it isn't absorbed and helps excrete it. The soluble fiber from oatmeal is also found in fruits and vegetables like apples and carrots and in legumes and dried beans."

For those who lament giving up ice cream, an occasional dish of ice milk can ease the pangs (although even ice milk contains other fats). Beware whipped toppings _ instead of cream you may be getting an equally dangerous dose of palm oil that will increase your body's production of cholesterol.

Eating out requires doing a little homework but one needn't give up this pleasure. Many restaurants are featuring entrees that are guaranteed "heart healthy" by the American Heart Association. Gould is involved with a program called "Dine to Your Heart's Content" that has local restaurants featuring a heart insignia next to meals that are low-cholesterol and low in saturated fat. A list of participating restaurants is available by calling the Utah Affiliate of the AHA. The pamphlet "Dining Out: A Guide to Restaurant Dining," that details recommended menu choices can be also be obtained by calling 322-5601.

Salt Lake restaurateur Jim Tsoufakis, owner of Maestro's Grill, uses his earlier training in pre-med and biology to benefit the health of his customers. He began five years ago to make his cooking healthier. "I use 2 percent milk in my restaurant and all deep frying as well as grilling is done with an all-vegetable shortening. We use margarine as much as possible but since foil wrapped individual portions of margarine are not yet available, margarine is available with bread on request." For his marinades and Greek dressing, Tsoufakis uses 100 percent virgin olive oil that is monounsaturated and contains no cholesterol. Important dietary fiber can be found in the old fashioned oatmeal served for breakfast or in the fresh, lightly steamed vegetables served with dinners. "The restaurant industry is very aware of the consumer's needs and eating out in a popular restaurant can actually be healthier than eating at home," Tsoufakis said.

Cholesterol watchers may find the new regimen restrictive at first and perhaps a little frustrating. But the glow of health will be well worth the effort and heart patients can then enjoy the old "Star Trek" dictum: "Live long and prosper!"

SUGGESTED READING: "Jane Brody's Good Food Book" W.W. Norton & Co.; "Seafood _ A Collection of Heart Healthy Recipes" by Janis Harsila and Eric Hansen and "Living Lean and Loving It" by Eve Lowry R.D. and Carla Mulligan Ennis, both available from Lowfat Lifeline, 52 Condolea Court, Lake Oswego, OR, 97035; "The New American Diet Book" by Sonja Conner, R.D. and William Conner, Simon and Schuster, 1986; and the "American Heart Association Cookbook," available at local bookstores.