(FORTUNE Magazine) – Last summer William Daiger could have dropped dead. Or he could have joined those who become permanently impaired when a heart attack destroys a significant part of the body's precious pump. But Daiger, 59, an executive vice president of the MBNA America credit card company, avoided both fates. Soon after he felt pain in his throat and neck, he went to Baltimore's St. Agnes Hospital, where medications kept the blockage in his coronary arteries from setting off a major attack. Says Raymond Bahr, St. Agnes's head of coronary care: "All three of Daiger's heart vessels were diseased. But he walked out with his entire heart muscle as well as his life." You, too, can join Daiger and others on these pages who have thwarted America's No. 1 killer, which mows down nearly half a million yearly and turns legions of others into cardio-cripples disposed to early death. New evidence, coming at blizzard force, removes any lingering doubt that lifestyle changes can keep you alive. But many doctors now stress that potential victims who learn to recognize early-warning signs that Dr. Bahr describes as "the body's smoke detector" may be able to prevent an attack. Even if they can't, recent findings nail the amazing advantage of getting to the hospital fast -- and thereby surviving. As cardiologists say, time is muscle. The best-known symptom of what they call an acute myocardial infarction -- the agony of an elephant's foot on your chest -- means that the heart muscle (myocardium) is crying for the oxygen it no longer gets because a clot has sealed a plaque-narrowed coronary artery. Once blood flow stops, myocardium begins to die, never to be replaced. But most of the threatened heart muscle can be saved if flow is restored within three hours. Better yet, as an important study of several hundred patients in the Seattle area by a team at the University of Washington has shown, the muscle loss (infarct) is inconsequential if a clot-dissolving drug is given within 70 minutes.The death rate among patients treated approximately within the "golden first hour" with Genentech's TPA, or tissue plasminogen activator, the Seattle researchers found, plunges from an average of 8.7% to 1.2%. This hardly means that you can go back to eating all the Brie you want. It is true that the heart attack mortality rate has been falling steadily for those who make it to the hospital, from more than 30% in the 1950s to about 10% today. But don't assume you'll reach the hospital. Half of all heart attack fatalities occur suddenly, and indeed heart attacks are the leading cause of sudden death for any reason. And chances are less than fifty-fifty that your heart attack will be the type that can be treated with clot-busting drugs. Despite big medical gains, in short, heart attacks remain a raging epidemic. Folklore depicts the overstressed white male as their principal victim, but they wipe out nearly as many women -- three times the number who die from breast cancer, the No. 3 killer of women, behind second-ranking lung cancer. The difference is that heart attacks are more likely to fell females who are in their retirement years. African Americans, especially women, fare worse than whites. But unlike cancer, this is one malady we know how to cut down to size. Speedier treatment with clot-busting drugs, says the Heart, Lung, and Blood unit of the federal government's National Institutes of Health, could save thousands of lives annually. Baltimore's Dr. Bahr, medical director of St. Agnes Hospital's Paul Dudley White Coronary Care System, thinks that far more could be spared if people were taught to heed that smoke detector's warnings of trouble brewing (see box for what you should look out for). Living wisely could save the most lives of all. Even though nobody can alter an inherited vulnerability to heart attacks, you can tip the odds by working on the other four big risk factors: smoking, high blood pressure, cholesterol, and the sedentary life. Sure, sure, you say, but how many people will summon up the required self-denial and energy? If you can't, the best bet is to try heading off a heart attack that's on the verge of happening. If you can't be virtuous, be vigilant. John Cunningham, 62, knew that his total cholesterol was high at 270 and his "good'' cholesterol -- the high-density lipoproteins (HDLs), which counter the buildup caused by low-density lipoproteins (LDLs) -- was running between 20 and 25, even though any reading below 35 brings added danger. Cunningham paid scant attention to diet. "Breakfast was four or five doughnuts," he recalls, "and that's all I'd eat all day." But because he is an internist, Cunningham knew enough to exercise on a NordicTrack at his home in Lake George, New York -- and to call a cardiologist when he felt nausea halfway through dinner. His wife, Marianne, immediately drove him to a hospital 20 miles away. On the way he began to have chest pain, and 45 seconds before reaching the emergency room he suffered cardiac arrest. His heart began writhing ineffectually with "ventricular fibrillation," unable to pump enough blood. Clot-dissolving drugs were considered too risky in Cunningham's case. But after a chaplain had given final rites, hospital personnel restored a normal beat with an electric defibrillator. Today, three years after returning from the dead and with 20% of his heart muscle gone, Cunningham says, "I can do anything I want." If Cunningham had waited until he felt unmistakable chest pain, he would now be below ground. For William Daiger, the smoke detector communicated via "funny feelings" in his neck and gums three days before the pain that forced his race to the hospital. Georgia Anderson, a suburban Baltimore housewife of 73 who actually had a heart attack, experienced pain in her left elbow during the previous three weeks while taking long walks with her husband. Edward Malan, 67, a staffer in the U.S. Senate, says that for "several weeks" before an attack he would wake up with his left shoulder feeling as if it had gone to sleep.

Baltimore's Dr. Bahr thinks that Daiger, Anderson, and Malan -- he treated all of them -- should have come in sooner, when they were in less danger. The time to attack heart attacks is before they occur, Bahr says, before the "occlusion," or closing of coronary arteries, leaves the medical system only a few frantic hours to minimize the damage. Says Bahr of the down-to-the- wire timing of such rushes to the hospital: "It's incredible that we start the meter with occlusion rather than before the heart attack occurs." Bahr talks insistently, for he is leading a crusade against heart attacks. He likes to tell of the time when, as a medical student working as a pharmacist, he met a tailor named Jake who came in complaining of indigestion and not looking well. Bahr urged him to get to a doctor but became busy with other customers and didn't press the point. Three hours later, Jake was dead from a heart attack. The incident left a lasting impression on Bahr, who believes that heart attacks can be toppled as the leading killer by the end of the century if, as he says, more people will only come to the hospital "before they crash, not after." Half of all heart attacks, Bahr says, have "prodromal" symptoms, or warnings that precede the commonly recognized ones like crushing pain. The most common tip-off, says Bahr, is nausea and "central chest discomfort that occurs in a stuttering fashion over a course of days." The on-off discomfort, adds Bahr, "gets worse with activity, is relieved by rest, and becomes longer each time, with shorter intervals in between." This may signify intermittent "ischemic" events, or shutoffs in the coronary arteries.

If you detect such warning signs, hurry to the hospital -- or to a chest pain center, a Bahr-inspired concept that has been spreading fast among hospitals. About a tenth of hospitals have built the centers, and the number is doubling yearly. St. Agnes's seven-bed unit, dating from 1981 and adjoining the emergency room, can quickly give you clot-dissolving drugs if you arrive in the midst of a full-blown heart attack. But most folks are there to get looked over in an atmosphere more user-friendly than a typical emergency room. Nobody scolds you if you turn out to have nothing but a pulled chest muscle.

Suppose the tests reveal an imminent heart attack? St. Agnes will "cardio protect" you -- Bahr's term -- with such drugs as heparin and aspirin, which help prevent clots from forming, or with nitroglycerin to dilate the blood vessels and beta blockers to slow the heart. Bahr's crusade also includes advocacy of a nationwide education effort that would teach spouses, teenage children, and others to spot warning signs and badger possible victims to go to the hospital before it is too late. For all this, Bahr's views are controversial within the medical community. Heart attack survivors have never been surveyed on a large enough scale to find out how prevalent the warning signs are. It's also unclear how many would respond to a stepped-up alertness program. Costas Lambrew, head of cardiology at the Maine Medical Center in Portland, argues that since it's already difficult enough to get some people to recognize a heart attack in progress, "you're going to have a hard time getting people to recognize less significant symptoms." Others are convinced that Bahr is on to something, among them Henry McIntosh of Tampa, a former president of the American College of Cardiology. He says that although there's no good number on how many heart attacks could be prevented if people got to the hospital before they occurred, "it's still a lot of people." Chest pain centers have their detractors too. In a recent issue of the Annals of Emergency Medicine, Drs. Robert Shesser and Mark Smith called them "an inefficient use of resources" and said many hospitals are building the ; centers as a marketing tactic. Dr. Thomas Lee of Boston's Brigham and Women's Hospital says these facilities could increase total medical spending by luring in more false alarms. But if the units are run efficiently, they could get the hospitals out of a serious dilemma. On the one hand, hospitals mistakenly send home 3% to 4% of the patients who turn out to have heart attacks because their symptoms are vague or iffy. Missed heart attacks are the biggest cause of malpractice judgments against emergency rooms and their physicians, with awards averaging $113,000 per case and often much more. Meanwhile, hospitals are spending as much as $4 billion a year nationwide on patients who are admitted for several days of evaluation but turn out to have nothing wrong. "You can spend $5,000 to $7,000 for somebody with an upset stomach," says Dr. Louis Graff of Connecticut's New Britain General Hospital.

Graff believes that tightly organized observation units within the emergency department, which would include Bahr's chest pain centers, may be just the way to catch more heart attacks at less cost. Five years ago, cardiologist Tony Joseph, now a consultant in Columbus, Ohio, helped to devise an outpatient observation system at the city's Riverside Methodist hospital. For the majority who could be safely released, screening time was cut to well under a day.

The focused approach drives down costs. In the four years since Dr. W. Brian Gibler set up the "Heart ER," a monitoring unit on the fringe of the busy emergency room at the University of Cincinnati Medical Center, about 1,300 people without definite signs of a heart attack have been given an evaluation that takes no more than 12 hours and costs less than $1,000 on average, half as much as the traditional inpatient routine. Through last June, as just reported in the Annals of Emergency Medicine, the unit had a perfect batting average. Of the 82% of patients deemed okay to send directly home, says Gibler, "to the best of our knowledge, nobody was having a heart attack." But the dragnet also picked up 5% with serious heart problems, including you know what.

Such feats don't necessarily require a brick-and-mortar investment in a formal chest pain center. At the Virginia Commonwealth University's medical center in Richmond, for example, people complaining of chest pain go to a traditional emergency room. Once there, however, they are treated according to an innovative triage system developed by emergency department director Joseph ! Ornato and his colleagues. It sorts patients into five levels of risk, ranging from an obvious heart attack (level one) to non-cardiac pain (level five). At level four are outpatients with signs of "possible unstable angina," the medical term for the ruptured plaque that can mean a heart attack on the way. Though most level fours go home after tests, others wind up in a hospital bed with far more serious problems that might have slipped through in the past.

"You're too young to have a heart attack" they told James Ampey, 43, when he arrived in the emergency room at Virginia Commonwealth University's medical center, where he had gone after finding himself out of breath and sweating. But because a heart attack had killed his father the previous year, they put him in level four for evaluation. Ampey's electrocardiogram was normal, and because his story was atypical they skipped time-consuming blood tests to detect telltale enzymes given off by dying heart muscle. Instead he was injected with a compound called Tc-99m sestamibi, tagged with a radioactive agent that allows a scanner to show how well the heart is pumping. Only then did the medical team discover that a portion of it was not getting enough blood. By then Ampey was feeling "a little pressure in my chest, like a baseball." Happily, the heart attack had barely begun, Ampey says. Following angioplasty, in which a balloon is inflated into an artery to push aside plaque and then withdrawn, he's back on the job as an air traffic controller at the Newport News, Virginia, airport.

There are powerful reasons, then, why you should rush to the hospital at the first hint of a heart attack. But do today's cost-conscious health insurance plans, and particularly health maintenance organizations, really want you to? Cardio-protection, while saving heart muscle and lives, may result in costly catheterizations for a peek at circulation in coronary arteries, not to speak of bypass surgery that can cost $50,000 or more.

Leading HMOs, including Kaiser Permanente and U.S. Healthcare, nevertheless say that members who think they may be having a heart attack should go promptly to the nearest emergency room. Even if the hospital isn't in the network, both HMOs insist, they'll pay the tab for a false alarm. "At the margin, it's probably cheaper medicine if you catch heart attacks earlier," points out James Field of the Advisory Board Company, a hospital-supported consulting organization in Washington, D.C. John McDonald, CEO of California's Mullikin Medical Centers, which serves many HMO patients for a capitated, or flat, yearly fee, thinks that even bypass operations pay for themselves if they prevent years of costly and debilitating illnesses that often follow a heart attack. But where does all this leave you if you belong to the luckless half of the population unendowed with a smoke detector and therefore deprived of a warning system? Better off than you might think, provided you follow the No. 1 rule: Move it. Too many go into denial when an attack happens, when they should be dialing 911.

Typically, it takes those experiencing heart attacks two hours or more to get to the hospital. That's twice the 60 minutes that the National Heart, Lung, and Blood Institute's heart attack alert program has adopted as the goal for total elapsed time from the appearance of symptoms to the administering of clot-dissolving drugs. At present, only a tenth of patients get the drug within an hour.

Speed is especially important if the drug is Genentech's TPA. At $2,200 a dose, TPA is only slightly more effective overall than the alternative, streptokinase, which costs one-fifth as much -- but TPA has an extra edge in a heart attack's early hours. "If you're going to spend $2,000 extra for a drug that works faster, you've got to give it faster," says cardiologist Christopher Cannon of Boston's Brigham and Women's Hospital. One way would be to give it before patients reach the hospital. But American doctors don't ride in ambulances, and paramedics rarely give the drug, because they feel uncomfortable doing so even when in telephone contact with a physician.

Some places are better for heart attacks than others. For example, try to keel over in a city like Richmond, where fire trucks and ambulances carry defibrillators. You should also look for a hospital with a low "door to needle" time, the interval between your arrival and the administering of clot busters. Figures from the National Registry of Myocardial Infarction, which collects data on heart attack outcomes from about a fifth of U.S. hospitals, show that their average door-to-needle time has fallen in the past four years from 62 minutes to 47 minutes. But that still exceeds the 30-minute target of the government's heart attack alert program. Sometimes the delay is in giving and reading an electrocardiogram after the patient reaches the hospital. Overlook Hospital in Summit, New Jersey, has found a way around that: At least half the time, paramedics give an electrocardiogram when they pick up the victim and transmit the squiggles ahead by cellular phone to the hospital, where they can be studied before the patient arrives. It obviously helps if emergency rooms are adequately staffed.

Look for a hospital with board-certified emergency physicians as well as a protocol for quickly handling heart attack victims, and a door-to-needle time of 30 minutes or less. One such hospital: Portland's Maine Medical Center, where the average door-to-drug time has lately been running at 17 minutes. Here's what actually happens. Within two minutes of your arrival with classic heart attack symptoms, emergency room personnel hook you up to a 12-lead electrocardiogram and a doctor spends a minute or so asking you about possible "contraindications" -- recent surgery, for example -- that would bar use of the clot-busting drug. Then you get the TPA. Whenever the total elapsed time exceeds 20 minutes, says emergency department head Dr. George Higgins III, "I want to know why it got screwed up."

Everything clicked for Omar "Chip" Crothers, 53. An orthopedic surgeon, he'd had angina of the less worrisome "stable" variety long before his heart attack a year ago. Following a party at which he hadn't felt well, he woke up with chest pain; the stable angina had become unstable. Crothers went through "denial for ten minutes" but figures that "within 90 minutes maximum" after awakening he was in Maine Medical Center with TPA being administered. Fifteen minutes later the pain stopped abruptly as blood flow was restored. Crothers later got a bypass operation when the angina returned, but he has lost only 5% of his heart muscle and can handle strenuous exercise like skiing. He has also gone on a vegetarian diet that has brought his cholesterol down to 180. Says Crothers: "I'm a pain in the ass to go to a restaurant with."

Crothers had had ample reason to change his ways before trouble came: sky- high cholesterol and a father who had died of a heart attack at 46. Others might not receive such clear warnings. Just remember that if you're in midlife, you need a billion heartbeats to stay around for 30 more years. Smoking and high blood pressure are well-known killers. So is cholesterol, which is emerging as an ever deadlier menace. At November's annual meeting of the American Heart Association in Dallas, researchers gave the stunning results of a five-year study of 4,444 Scandinavian men and women with moderate to high cholesterol and a history of prior heart attacks or chronic angina chest pain. Those who took the cholesterol-lowering drug simvastatin brought their cholesterol readings down by an average 25%. Their death rate from heart disease plunged 42% below that of a control group taking a placebo.

The really hot news was that among those taking the drug, the death rate from all causes was 30% lower. This finding quashed for the first time the worry that curbing cholesterol may create other problems, such as cancer or suicidal depression. Simvastatin is sold under the brand name Zocor by Merck, which funded the study. It is in the same family as Merck's Mevacor and other cholesterol-loweri ng drugs from Bristol-Myers Squibb and Sandoz. The landmark study dovetails with others indicating that drugs or diet can work as a kind of Drano to help clear your coronary arteries. When the cholesterol level in the blood falls significantly, scientists find, fatty plaques prone to fissuring and other disturbances that invite clotting tend to stabilize and even regress.

What can you do with this new knowledge? Plenty. The familiar injunction to hold down saturated fat in the diet, which comes mainly from meat and dairy products, is more compelling than ever. At least you can wash down your sensible diet with a little wine. The French are right. Researchers are finding that alcohol boosts your beneficent HDL cholesterol and your body's natural supply of clot-busting TPA. But keep your alcohol intake moderate; two drinks per day for men, one for women. Otherwise you court such scourges as cancer and cirrhosis of the liver.

Couch potatoes face their own assortment of cardiac risks, particularly if they leap up and try to lift the couch. Sudden exertion, as well as anger, can trigger a heart attack by disturbing those clogged coronary arteries. Dr. James Muller, co-director of Boston's Institute for the Prevention of Cardiovascular Disease, found that folks who rarely exercise increase their chances of a heart attack 107-fold in the hour following strenuous activity such as snow shoveling. Those toughened by heavy exercise, on the other hand, face little more than a doubling of risk. Even a less than rigorous regimen helps. Heart problems decline 25% for sedentary people who begin to exercise moderately in middle age, says Emory University cardiologist Gerald Fletcher. He puts the minimum protective amount of exercise at five or six miles of brisk walking, running, or its equivalent spread over a week. Your heart. Your move.