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When a heart attack strikes, time is of the essence. Intuitively, we all know it: The faster we get help, the better the outcome. Doctors say that “time is muscle,” because the longer a heart attack goes untreated, the more heart muscle dies and is irrevocably lost.
But statistics show that most people don’t receive treatment within the critical 60–90 minutes after a heart attack starts. Emergency departments have worked hard to reduce the time it takes for a person to receive treatment, and local emergency medical services have improved significantly in the past few decades. As it turns out, however, the biggest delay in treatment occurs before the professionals even get involved.
The most common reason for delay in treatment of a heart attack, according the National Heart, Lung, and Blood Institute (NHLBI), is the time it takes the person to seek help. The NHLBI says that median time from onset of symptoms to calling for help ranges from 2 to 6.4 hours.
All people need to be more aware of the symptoms of a heart attack and know how to respond quickly, but it’s even more important for people with diabetes because they have a 2–4 times higher risk of heart attack and other heart disease. They’re more likely to die before reaching the hospital with a first heart attack and more likely to die in the hospital while undergoing a cardiac procedure, and they do less well following a heart attack or an intervention such as surgery. The rate of death for the five years following a heart attack is as high as 50%, or twice that of people without diabetes.
In the general population, heart attack risk is higher in men than in women under 50 years of age. Diabetes erases that difference, causing an increased risk in women with diabetes.
There also are associations with other diabetes complications. For instance, cardiovascular mortality is much higher among people with end-stage kidney disease, as much as fivefold higher in the elderly. The effect apparently begins early: Cardiovascular complications increase as kidney function diminishes.
This increased risk of heart disease applies both to people with Type 1 diabetes and those with Type 2 diabetes. Researchers have found early signs of heart disease even in relatively young people with Type 1 diabetes who had no symptoms.
The mystery of delay
Why would someone with diabetes delay seeking treatment for a heart attack? Part of the reason seems to be misperceptions about who’s at risk for a heart attack. One survey, published in February 2002 by the American Diabetes Association (ADA) and the American College of Cardiology, reported that half of people with diabetes do not believe they are at higher risk for heart disease. Sixty percent did not feel they were at risk for high blood pressure or high cholesterol, two important cardiovascular risk factors that often accompany diabetes. Half of the people surveyed reported that their physicians had never discussed reducing risk factors such as blood pressure or cholesterol. A third of those who smoked (smoking is a risk factor for heart disease) said they had not been advised to quit.
These findings are consistent with other epidemiologic studies investigating preventive care for people with diabetes. Published reports of prophylactic aspirin therapy use among people with diabetes, for instance, range from 5% to 18%, despite guidelines suggesting that most people with diabetes should be on aspirin therapy.
The message is clear: People with diabetes need to recognize their increased risk of heart disease, and they need to ask their physicians about prevention and about what to do in an emergency.
“There are many reasons people delay seeking treatment,” says Costas T. Lambrew, MD, retired director of the Division of Cardiology at Maine Medical Center in Portland, Maine. Dr. Lambrew served on the National Heart Attack Alert Program committee of the NHLBI, charged with investigating delay both before and after arrival at the hospital. “They don’t recognize the symptoms, or they say ‘it can’t be’ a heart attack,” he says. “Many people also don’t want to cause a fuss by having an ambulance pull into their neighborhood in the middle of the night, or they don’t want to inconvenience the paramedics. People who have had a heart attack often delay until the symptoms are as bad as they were the first time, which of course is the wrong thing to do.”
Emotional and social barriers also play a major role in the delay of treatment. “Women delay more than men,” Dr. Lambrew says, “perhaps because they have a higher pain threshold, and also because they frequently experience more subtle symptoms than men.” Ignoring nonclassic symptoms or having a mistaken perception of risk can cost precious time. In one survey of women (with and without diabetes), many mistakenly believed that cancer was the leading cause of death for women when, in fact, heart disease and stroke kill more than twice as many women as all cancers combined. Heart disease was long portrayed as a disease that mainly affected men, so women, especially women with diabetes, need to be aware of their actual level of risk.
What’s happening to the heart?
People with diabetes often have atypical heart attack symptoms, and sometimes they have no symptoms at all. This may be another reason why people with diabetes are more likely to delay seeking treatment. The incidence of silent myocardial ischemia, or symptomless heart attacks, is as much as 30% higher in people with diabetes than in people without diabetes.
The causes of silent ischemia are not fully understood, but there appears to be an association with cardiac autonomic neuropathy (CAN). CAN is similar to the sensory neuropathy that can cause numbness, tingling, or pain in the feet and legs of people with diabetes, in that it is caused by damage to the nerve fibers around the heart. CAN also may increase the risk of cardiovascular events by itself, although the mechanism has not been completely explained.
All these symptoms, silent or not, are caused by a physically tiny problem. The heart’s blood supply comes from three major coronary arteries. (See this illustration.) These arteries divide and subdivide, with the branches feeding all of the heart muscle. A heart attack occurs when there is a blockage in one of the coronary arteries, usually caused by a clot. The clot often starts with the rupture of a plaque, or fatty deposit, that has built up in an artery wall. (These deposits are the results of the disease process known as atherosclerosis.) The body’s natural healing response is to cause clotting at the site of injury, but clotting in a vessel already narrowed by atherosclerosis can cut off the supply of oxygen-laden blood to parts of the heart muscle. The muscle tissue begins to die after even a short time without oxygen.
Preventing a heart attack
“A” is for A1c, or HbA1c, a blood value that measures control of blood sugar over time. People with diabetes should target a value below 7% to reduce their risk of heart attack and other cardiovascular problems. The impact is considerable: Studies have demonstrated that for every 1% increase in HbA1c, the risk of a cardiovascular event increases 10% to 30%.
“B” is for blood pressure, which is a cardiovascular risk factor for all people, with diabetes or not. People should strive for a blood pressure of 130/80 mm Hg or less. Every 10-point increase in systolic (the first number) blood pressure has been correlated to a 20% increase in cardiovascular risk.
“C” is for cholesterol, specifically the LDL, or “bad,” cholesterol. The target is an LDL level of less than 100 mg/dl. Data from the United Kingdom Prospective Diabetes Study demonstrated that every 39-point increase in LDL increased cardiovascular risk by 50%, and that those with levels over 151 mg/dl were 2.3 times more likely to have cardiovascular complications than people with LDL levels below 117 mg/dl.
There are a range of medicines that can help people with diabetes achieve these goals, and modifications in diet and exercise have also been shown to be very important as a first-line treatment.
In addition to controlling blood sugar, blood pressure, and cholesterol, many physicians advocate that people with diabetes take aspirin to help prevent blood clots. Diabetes both increases the tendency of blood to clot in the blood vessels and decreases the natural process that dissolves clots.
Current treatment guidelines from the ADA recommend 81–325 milligrams of aspirin each day for anyone over 30 with Type 2 diabetes at risk for heart disease. Since diabetes is now considered a “risk factor equivalent” for heart disease, many physicians recommend that all people over 30 years of age who have diabetes take aspirin.
There is still debate about how to approach control of risk factors in people with diabetes, but many physicians suggest starting aggressive management upon diagnosis or even upon diagnosis of prediabetes, a syndrome of insulin resistance and/or impaired glucose tolerance.
Michael Brownlee, MD, a researcher at Albert Einstein College of Medicine in New York, believes that aggressive drug therapy is a good idea for everyone diagnosed with diabetes, whether Type 1 or Type 2.
“The ‘triple therapy’ for Type 2 diabetes, whether you have other risk factors or not,” he notes, “is a statin drug to lower lipid levels, aspirin to help prevent clotting, and an angiotensin-converting enzyme (ACE) inhibitor to reduce blood pressure. My opinion is that people with Type 1 diabetes should be on the same therapy, early in their treatment. Given the similar metabolic abnormalities, the reality that these drugs have a low toxicity, and the protective effect of ACE inhibitors on the kidneys, it would be prudent to start treatment early.”
There is also controversy about the impact of hormone replacement therapy (HRT) on heart disease risk. HRT once was thought to help prevent heart disease in postmenopausal women, but more recent controlled trials have found no benefit. One study of particular interest to women with diabetes, published in February 2003, reported that in women with diabetes taking HRT, there was a significant increase in the risk of death from heart attack, and in fact an increased risk of death from all causes. In 2004, the American Heart Association issued updated guidelines on preventing heart disease in women; these guidelines recommended against using HRT for this purpose.
In an emergency
“When you look at all the data from all the studies,” Dr. Lambrew says, “you can calculate that there are 10 lives lost per 1,000 heart attacks, for each hour of delay. The ‘60 Minutes to Treatment’ working group that I served on paid particular attention to reducing the delay once the patient arrives at the Emergency Room. We can’t control the time delay before arrival, except by educating people and encouraging them to move quickly.”
In most areas of the United States, 911 is the emergency response number. However, some areas do not have 911 service yet, so it is important to have the right local number handy. Calling a physician or the hospital before calling 911 creates unnecessary delays.
The NHLBI also recommends that the safest and fastest way to the hospital is by ambulance. Many people try to drive themselves or have a relative or friend drive them. A seriously ill person can endanger themselves and others by trying to drive, and a relative or friend may not be able to render lifesaving care — and certainly could not do it while driving. Emergency medical services teams, by contrast, can both drive and treat at the same time, and can prepare the hospital for your arrival.
Physicians may advise their patients to chew an aspirin tablet when they experience symptoms of a heart attack, because aspirin has an immediate clot-dissolving effect. Aspirin isn’t for everyone, though, so each person needs to seek advice ahead of time. People who have had previous heart attacks may also be advised to take a nitroglycerin tablet if symptoms appear.
At the hospital, people who are having a heart attack will be met with an array of treatments that could only be imagined a couple of decades ago. They can make heart attack treatment much more successful, especially when started early.
Thrombolytic agents, or “clot-busters,” revolutionized heart attack care when they were introduced in the 1980’s, and they are available in virtually every emergency room in the United States.
A growing trend in heart attack care is primary angioplasty. Angioplasty is the use of a catheter-borne instrument to open up a clogged coronary artery. Most often performed as an elective procedure, it is becoming popular as the initial treatment for heart attack at hospitals where it is available.
An interesting phenomenon that is under investigation is the impact of blood sugar levels during a heart attack. Researchers have found that there may be a benefit to quickly lowering blood sugar levels during a heart attack and keeping them low afterward. The Diabetes Insulin Glucose in Acute Myocardial Infarction (DIGAMI) trial used an insulin–glucose infusion during the first 24 hours of acute treatment, followed by intensive insulin treatment for three months. A year after treatment, 26% of the group receiving standard care had died while 19% of those receiving the insulin–glucose infusion treatment had died. At three years, 44% of the standard-care group had died compared to 33% of the insulin–glucose group.
This and other studies have renewed interest in the use of insulin not only during heart attack but during cardiac surgery. There is no consensus, however, so it is not yet recommended treatment.
An early warning for diabetes?
Another study published in 2002 documented a substantially increased risk of cardiovascular disease prior to clinical diagnosis of Type 2 diabetes in women. What’s more, the risk began to increase at least 15 years before diagnosis.
The study hearkens back to research published as early as 1990, in which it was proposed that the “clock starts ticking” for heart disease decades before the clinical onset of Type 2 diabetes. Findings like these have increased interest in taking advantage of the connection between diabetes and heart disease to conduct effective early screenings.
“There is currently a national task force at work examining the value of screening people with coronary disease for diabetes, and screening people with diabetes for coronary disease,” Dr. Lambrew says. “The American College of Cardiology and the ADA have formed an alliance to emphasize prevention and early detection.”
Taken together, it would appear that there are good reasons for people with diabetes to keep a watch on cardiovascular risk factors, to know the symptoms of a heart attack, and to know what to do in an emergency.
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