Finding out that you or a loved one has coronary artery disease—known as CAD for short—can be upsetting. But you’re not alone and there is good news: More people are living with CAD than ever before thanks to earlier diagnosis and better treatments.

We often take our heart health for granted. When we’re young, it’s easy to pass heart disease off as something that afflicts only older generations. But it’s not always so.

In fact, heart disease is becoming more common at younger ages due, in part, to climbing rates of diabetes and obesity. We know women with diabetes develop heart disease at younger ages. And all women have a higher chance of heart problems after menopause.

Heart disease is the No. 1 killer of both men and women. Yet, many misunderstandings remain about how heart disease affects women. Learning about heart disease is one of the best ways women can protect their hearts.

All told, 80% of heart disease and stroke events could be prevented through healthy lifestyle changes. But women, in particular young women, are largely unaware of their personal risk or chance of getting heart disease.

If you are a woman or care for one, keep these points in mind:

Heart disease is not only a man’s disease

Coronary heart disease affects women and men alike, but women tend to have worse outcomes. For example, more women die of coronary artery disease than men and fewer women will survive a first heart attack.

Women surviving a heart attack also tend to have longer hospital stays and higher chance of death while in the hospital.

Heart disease kills more women than all cancers, including breast cancer

On average, 1 in 3 women will develop heart disease at some point in their lifetime compared with 1 in 8 who will get breast cancer.

Heart disease can happen at any age

While coronary heart disease is more likely to develop as we age, it can also strike younger women. For example, heart disease can happen in young women who have:

• Pregnancy-related complications such as spontaneous coronary artery dissection (SCAD), a sudden tear in one of the heart’s blood vessels
• Coronary vasospasm, an abrupt tightening and narrowing of the heart’s arteries due to spasm in the muscle layer of the artery
• Premature narrowing of the heart’s arteries (atherosclerosis, plaque)
• Familial hypercholesterolemia, a genetic disorder passed down in families that causes dangerously high levels of LDL or “bad” cholesterol, generally LDL levels over 190 mg/dL

You may not be as heart healthy as you think

Most women – 9 out of 10 – have one or more risk factors for heart disease or stroke.

The good news is that many of these risk factors – such as high cholesterol, high blood pressure, being overweight, or smoking, for example – are modifiable.

That means you can take steps to reduce your risk, such as giving up smoking, maintaining a healthy weight, finding ways to fit more activity into your life, and eating more fruit, vegetables and fish. There are also risk factors that affect only women.

Heart disease can look very different in men and women

Men are more likely to develop the “classic” narrowing or blockage in the coronary arteries, the blood vessels that supply blood to the heart itself, which can be detected with standard testing.

But women may not have the classic, isolated obstructive blockages typically seen in men, yet they still have reduced blood flow to the heart or suffer a heart attack.

For a long time, when no obstructive coronary lesion was seen, these women were told there was nothing wrong with their hearts. But we now know from research that this is not the case.

Symptoms of a heart attack can be and feel different, too

For some women, the first sign of heart disease is a heart attack, heart failure or a problem with the heart rhythm.

Because coronary artery disease can be silent or subtle, knowing your risk factors now and as you get older is critical.

Not all treatments are equally given

While there have been major advances in treating heart disease, women are less likely than men to receive potentially life-saving treatments.

Women are less likely to receive early aspirin, beta blockers and other guideline-recommended therapies.

They are less likely to undergo reperfusion and other treatments, and less likely to be offered preventive advice about how to make heart-healthy lifestyle changes. Interventions, including stenting or bypass surgery, tend not to be used as aggressively in women.

After a heart attack, women are also less likely to take part in cardiac rehabilitation, which can improve overall health, and prevent deaths and repeat heart attacks.

Pregnancy is a natural stress test on the heart. Why? As soon as a woman becomes pregnant, many changes begin in the body, including a dramatic rise in blood flow and extra workload on the heart. These are all healthy and normal parts of helping to nourish the growing baby, and most moms-to-be won’t have any heart troubles during pregnancy.

But for a growing number of women, pregnancy may bring about new – often temporary – spikes in blood pressure or blood sugar levels.

• High blood pressure in pregnancy, also referred to as hypertensive disorders of pregnancy, may be pregnancy-induced high blood pressure (gestational hypertension), preeclampsia, or eclampsia. It also can be due to chronic high blood pressure.
• Elevated blood sugar during pregnancy, specifically if you had gestational diabetes, increases your risk for heart disease and diabetes as well.

These conditions typically return to pre-pregnancy levels soon after childbirth. But having them at all has been linked to a greater chance of developing heart disease, future high blood pressure and diabetes later in life.

In addition, it seems preterm birth (having a baby before 37 weeks of pregnancy) may be a red flag for future heart issues and stroke. Also, if you delivered a small baby, known as small for gestational age (in the lowest 10^th percentile), you are at a greater risk for heart disease as well. 

Take Charge of Your Health

If you’ve had high blood pressure – including gestational hypertension or preeclampsia – gestational diabetes, or delivered a baby earlier than 37 weeks, listen up.

Although these conditions often disappear after having a baby, simply experiencing them puts you at much greater risk of heart disease or stroke in the next 10 years. Here are steps you can take:

• Make sure your health and heart are protected.
• Let your health care providers know if you developed any of these conditions during pregnancy, and encourage other women to do so, too.
• Learn about your risk of heart disease and stroke now and in the future.

Why does the heart work harder during pregnancy?

A host of changes occur when you are pregnant. For example:

• The amount or volume of blood in your body increases about 50%.
• Your heart begins to pump a lot more blood out to the body each minute (increased cardiac output).
• Your heart rate quickens – usually by 10-15 beats per minute.
• Your blood pressure drops a bit due to changes in hormones.

Because of all these changes – and a growing baby – you may tire more easily or feel short of breath or lightheaded when doing things that require physical effort or when talking.

In addition, hormonal and metabolic changes affect how blood sugar levels are regulated. Changes in how your body forms clots needed to prevent excessive bleeding after delivery make pregnant women more prone to develop blood clots in the legs (called deep vein thrombosis).

Red flags for future heart problems

For some women, pregnancy can lead to (mostly temporary) problems that may make heart disease or stroke more likely in the future. These conditions are sometimes called “adverse pregnancy outcomes.”

Researchers don’t yet know whether pregnancy causes these issues or if a woman’s predisposition to heart problems first shows itself during pregnancy.

But more awareness and action is needed to better meet the health needs of women with these conditions. Many experts suggest these women should be screened for cardiovascular disease over time and given tips on heart-healthy living.

High Blood Pressure and Preeclampsia

What it is

Preeclampsia occurs when a pregnant woman develops high blood pressure and protein in the urine after the 20th week of pregnancy. A urine sample is taken at most obstetrician visits to check for this condition. It affects up to 8% of all pregnancies and usually occurs in mid-to-late pregnancy and up to six weeks after delivery.

Some women get high blood pressure for the first time during pregnancy without protein in the urine (also called gestational hypertension), which alone is concerning and can complicate pregnancy. It also can lead to preeclampsia.

In particular, preeclampsia may be characterized by:

• Blood pressure of 140 mmHg/90 mmHg or greater
• Protein in the urine
• Swollen feet, legs, fingers and hands

Symptoms of severe preeclampsia may include headache, changes in vision, stomach pain, nausea or vomiting.

Why the concern

Preeclampsia can be very dangerous – and sometimes even life-threatening – for mom and her unborn baby. It can lead to seizures (eclampsia), damage to the liver and blood cells (HELLP syndrome), stroke and early birth. If you have preeclampsia, your health care team will monitor you closely and will induce labor at 37 weeks to prevent further problems.

But even after preeclampsia goes away – often within weeks to a few months after having a baby – women who’ve had it are more likely to develop heart and vascular problems, including:

• Risk factors such as high blood pressure and diabetes
• Heart disease
• Stroke

And this risk remains over time. One study showed that compared with women with normal blood pressure readings during pregnancy, those who developed preeclampsia had a higher risk of high blood pressure over the next four decades.

What you can do

• If you had high blood pressure or preeclampsia during pregnancy, make sure this information is added to your health records for follow-up.
• Also, tell all your doctors that this problem occurred.
• Talk with your provider about your risk for heart disease.
• Advocate for yourself and commit to a heart-healthy lifestyle.
• Remember: You are more likely to develop preeclampsia again with future pregnancies, so talk with your doctor.

Gestational Diabetes

What it is

A form of diabetes in which the body doesn’t produce enough insulin to control blood sugar during pregnancy. As a result, women have higher than normal blood sugar (glucose) levels.  Also, the baby may be large at birth, frequently over 9 pounds.

Gestational diabetes, which affects 7-9% of pregnancies, usually starts around the 24th week of pregnancy, which is why a blood sugar test is often done between 24 and 28 weeks of pregnancy. If you develop diabetes during pregnancy, careful blood sugar monitoring, diet, exercise and taking insulin, if needed, are important.

Why the concern

In most cases, this type of diabetes returns to pre-pregnancy blood sugar levels soon after childbirth. But having it at all heightens your risk for type 2, or adult onset, diabetes later in life. In fact, about half of all women who had pregnancy-related diabetes will develop type 2 diabetes, according to the Centers for Disease Centers for Disease Control and Prevention and Prevention.

Diabetes at any age makes heart disease more likely. Experts say that even if you don’t develop diabetes at some point after your delivery, a history of gestational diabetes still puts you at risk of heart disease. It can also damage some organs (for example, your heart, kidneys, nerves or eyes) by causing changes to the blood vessels that supply them. Yet most women are not followed for this condition after pregnancy.

It’s important to follow up with your health visits and pay close attention to blood sugar, weight, diet, lifestyle and cardiovascular risk factors.

What you can do

• Make sure all your doctors know that you had diabetes during pregnancy and that it is noted in your health history.
• The American Diabetes Association recommends testing again for diabetes at 6-12 weeks postpartum; if your blood sugar level is normal, remind your doctor to check your blood sugar every one to three years to ensure it is detected early.
• Talk with your care team about ways to prevent or delay the onset of type 2 diabetes through exercise, eating a healthy diet and taking medications, if needed.
• Ask about other heart disease risk factors and how to prevent or manage them.

Preterm Birth

What it is

When a baby is born too early, before 37 weeks of pregnancy (about three weeks before a baby’s expected due date). Preterm births affect about 1 out of 10 pregnancies in the U.S.

Why the concern

Research has linked early deliveries to a higher risk of cardiovascular disease, cardiac events and related hospitalizations in moms. In fact, a recent review of existing studies found that preterm birth is associated with up to a 2-fold higher chance of developing or dying from heart disease or stroke later in life. The risk of heart and vascular diseases appears to be even greater among women who:

• Deliver before 32 weeks of pregnancy
• Have had more than one preterm birth
• Have a preterm birth due to a medical cause (not an early delivery that happens on its own)

What you can do

• Tell your primary care doctor and other health care providers that you had a preterm birth. This information should be part of your ongoing health history long after the baby arrives.
• Ask about doing a formal heart disease risk assessment
• Work together to decide when and how often you need to be followed.
• Live heart healthy by exercising daily, eating right, not smoking, managing stress, and knowing your cholesterol and blood pressure numbers.

Tips for Taking Care of You

Don’t despair if you or a loved one had a hypertensive disorder of pregnancy, such as preeclampsia, or diabetes during pregnancy, or a preterm birth. You can take steps to protect your heart and overall health post-pregnancy.

Start with knowing your likelihood for developing cardiovascular issues and reminding your doctors about your health history.

Stay positive and live a heart-healthy lifestyle:

1. Adopt a healthy eating plan, such as a plant-based one
2. Get regular exercise
3. After your pregnancy, reach and maintain a healthy body weight
4. Avoid smoking
5. Limit how much alcohol you drink
6. Get enough sleep
7. Manage stress
8. Know and keep up with your risk for heart disease and stroke. Remember to talk with your health care team if you had problems during pregnancy – even if they were years ago or have gone away. You can work together to come up with a plan to track and manage your risk over time.

1. Take stock of your heart disease risk at every age.

We change as we age, and so do our risk factors.

If you are approaching menopause or have had a pregnancy with a preterm delivery, gestational hypertension/preeclampsia or gestational diabetes, ask for a cardiovascular risk assessment to learn how these events can affect your chance of having future heart problems.

2. Schedule routine health checkups and mark the dates on your calendar.

Important numbers are measured at these visits:

• Your weight
• Body mass index (BMI)
• Waist measurement
• Blood pressure
• Blood sugar
• Cholesterol levels

3. Know and keep track of your numbers.

Keep a notebook or use an app to track your numbers over time.

For example, do you know your blood sugar, blood pressure, blood cholesterol levels and weight? Are they under control or within a healthy range?

4. Start or step up your exercise program.

Aim to get 30-45 minutes of exercise most days.

Pick activities that get your heart pumping and that you enjoy. Walking, riding a bike, swimming—even gardening or heavy housework—count.

Talk with your health care provider about what exercise routine is best for you.

5. Maintain a healthy weight.

Ask your provider what that number is, and pay attention to the fat around your waist.

Women with more of an apple-shaped body and too much fat around their waists appear to be at higher risk of serious heart issues.

Know your body mass index (BMI) and waist circumference.

6. Eat a healthy diet.

Make healthy food choices every day. Learn which foods have hidden fats, empty calories and added sugars.

The Mediterranean and the DASH diets are two examples of heart-healthy plans. Plant-based diets rich in whole grains, fruits and vegetables with lean protein are also good for heart health. 

And don’t forget to control your portions.

7. Quit or don’t start smoking.

Ask your doctor for information to help you stop smoking.

8. Reduce your stress.

Too much stress can affect your health, so it’s important to figure out ways to cope with stress.

Find time for yourself and to connect with what’s important to you. Listen to your favorite music, meditate, try out a fun exercise or yoga class, or go for a walk with a friend.

If you feel overwhelmed at work or home, ask for help and only say “yes” to what you can handle.

9. Get enough sleep.

Insufficient sleep is bad for the heart – not to mention for your overall health. Not getting enough quality shuteye is linked to a higher risk of high blood pressure.

A good rule of thumb for adults is to clock at least seven hours of restful sleep a night. Poor quality sleep may be due to sleep apnea, a sleep breathing disorder that is commonly associated with snoring and frequent disruption of sleep.

Talk with your health care provider about sleep habits, especially if you often wake up feeling unrested.

10. Limit alcohol to one drink a day or less.

Too much alcohol can lead to weight gain, raise your blood pressure, and affect your heart rhythm.

11. Listen to your body.

If you have a feeling that something is wrong, get it checked out. If you think you are having a heart attack, call 911. Early diagnosis and treatment are critical, and may even save your life!

Treatment

There are several treatment options for coronary artery disease, including lifestyle changes, medications, surgery and/or medical procedures.

Lifestyle changes are the mainstay of therapy. Commit to putting your health first:

• Make healthy food choices to eat more whole plant-based and less processed foods.
• Lose weight if needed.
• Quit smoking or don’t start.
• Reduce stress.
• Get enough sleep.
• Limit alcohol intake to one drink a day or less.
• Know your blood pressure, cholesterol levels and find out if you have elevated blood sugar or are at risk for diabetes.

Women often are the ones juggling tasks and taking care of everyone else first. By making these heart-healthy choices every day, you can help protect your heart and help those around you live healthier, too.

In addition to lifestyle changes, you may need:

• Medication. People who have or are at high risk for coronary artery disease are often advised to take one or more medications. Medicine can help the heart work better, lower blood pressure and cholesterol, manage symptoms including chest pain (angina) and/or prevent blood clots.
• Coronary angioplasty and stenting (also called percutaneous coronary intervention). This procedure opens the narrowed or blocked blood vessels that supply blood to the heart. A stent is a small, metal mesh tube that is expanded inside a coronary artery to keep it propped open. Angioplasty is a balloon procedure to open blocked arteries. Your doctor will decide which procedure is right for you based on your test results.
• Heart surgery or coronary artery bypass grafting (CABG). Surgeons will open the chest to place artery or vein grafts that reroute blood flow around the blocked or damaged arteries that supply the heart.  This will restore blood flow to the heart muscle.
• Cardiac rehabilitation. Cardiac Rehab is a 12-week program that includes a mix of supervised exercise in addition to nutrition counseling, stress management, help to quit smoking, and education about the disease process, including how you can better take control of your health and improve outcomes. Studies show that people who complete cardiac rehab have fewer returns to the hospital and better quality of life.  Unfortunately, more women opt out of Cardiac Rehab or do not complete the full program.

Historically, treatments have been based on clinical studies that included mostly men. In fact, less than 25% of participants in heart-related studies have been women. The good news is that as research continues to evolve and include more women of all races and ethnicities, researchers are beginning to find diagnostic approaches and therapies that are better matched to women with coronary artery disease.

Make sure you are getting the best possible treatment. If you have coronary artery disease or have a high likelihood for developing it, take the time to talk with your doctor about whether you are getting the guideline-recommended therapies. Women are less likely to get them. This includes aspirin and referrals to cardiologists, as well as cardiac rehab.

Prevention

Women are natural caretakers – whether it’s as a mother, sister, daughter and/or partner. Often, women are so busy caring for everyone else that their own health and well-being slips to the bottom of the list. Sound familiar? If so, for your loved ones and your heart, commit to making you and your health a priority.

Take time to understand how likely you are to develop heart disease and what you can do to prevent it. This way, you’ll be taking steps to be here and healthy for the people who mean the most to you.

Heart disease symptoms can look and feel very different in men and women.

Although many women will have the classic crushing central chest pain, which is often thought of as the hallmark sign of a heart attack, women often experience three or more additional symptoms when they have a heart attack. Tragically, heart attack or sudden cardiac death can be the first symptom of coronary artery disease in women, especially younger women.

This underscores the importance of always knowing your risk factors for heart disease – you won’t know if you don’t get checked. High blood pressure, for example, is often called a “silent killer” because it has no symptoms. In other words, the only way to know if your blood pressure is high – or becoming too high – is to check your blood pressure readings over time. Uncontrolled high blood pressure is a leading cause of heart attack and stroke.

What a Heart Attack Feels Like

Chest pain or discomfort is the most common symptom of a heart attack for both men and women. But women are more likely than men to have additional symptoms as well, such as nausea and shortness of breath.

Chest Pain Can Feel Like	Other Symptoms Include
Chest pressure, tightness, squeezing or burningDiscomfort in your chest, shoulders, arms, back, neck, or jawPain that travels down one or both armsShortness of breath	Unusual or extreme tirednessFeeling dizzy or lightheadedNausea or vomitingCold sweatAnxiety

There are many ways CAD can be diagnosed. Visit the Exams and Tests section of our Coronary Artery Disease resource. 

The choices you make every day can play a large role in determining your risk for coronary artery disease and how quickly it might progress. Positive lifestyle changes are very important and can help to prevent CAD and delay its progression.

Most women – 9 out of 10 – have at least one risk factor for heart disease or stroke. The good news is 80% of heart disease and strokes can be prevented through lifestyle change.

Cardiologists say one of the most important things you can do for your heart health is to understand your personal risk of developing heart disease. That means you should know:

• What makes it more likely you will have heart disease
• What you can do to lower your chance of developing heart disease

Traditional risk factors

For women, it’s especially important to talk with your health care provider about traditional risk factors linked to heart disease, as well as those that are specific to being a female.

The better-known indicators for heart disease include:

• Smoking
• Having high blood pressure, high cholesterol, or diabetes
• Not exercising routinely or sitting for long periods of time
• Eating a diet high in processed foods, salt, saturated fats, cholesterol and added sugars
• Being overweight or obese
• Family history of early heart disease
• Older age

Race, such as being Black or South Asian, also is linked with a higher risk.

Diabetes, mental stress/depression, obesity and smoking tend to play a bigger role in the development of CAD in women compared with men.

Female-specific concerns

Also, be certain to discuss risk factors that are unique to women. These conditions are known to up the likelihood of heart disease. For example:

• Menopause – Heart disease can happen at any age, but it tends to increase in women around or after menopause.
• Having started menstruating before 10 or after 17 years of age.
• Health problems during pregnancy
  • Hypertensive disorders of pregnancy – including gestational high blood pressure, preeclampsia, eclampsia, or chronic high blood pressure – or any elevation in blood pressure increases the chance of heart disease in women.
  • Gestational diabetes during any pregnancy.
  • Preterm delivery (delivering before 37 weeks of pregnancy).
  • Having a small-for-gestational age baby (in the lowest 10^th percentile)
• Polycystic ovarian syndrome (many ovarian cysts).

Oral birth control, if you smoke, is also a concern.

Less common conditions

Women are also more likely to have the less common conditions linked to coronary artery disease. These include:

• Heart disease that affects the smaller arteries supplying the heart (microvascular): These are typically due to dysfunction of the arteries and not complete blockages. Standard tests aren’t designed to diagnose microvascular endothelial dysfunction.
• Spontaneous coronary artery dissection (SCAD).
• Autoimmune diseases, such as lupus (SLE) or rheumatoid arthritis (RA).
• Broken heart syndrome, also called Takotsubo Syndrome or stress cardiomyopathy. Despite the name, it can occur with overwhelming good or bad emotional excitement.
• Breast cancer: Although not exclusive to women, it certainly occurs more often in women. The chemotherapy and radiation for breast cancer can damage the heart, both acutely and in the future. Knowing your risk for heart disease and controlling risk factors is important after breast cancer. It is now more likely you will die from heart disease than breast cancer because the treatment for breast cancer has been so successful. Having a history of breast cancer should be considered as a risk factor for heart disease.

If you are a woman – or care for one – listen up!

Heart disease is the leading cause of death in women in America. Each year, heart disease and related risk factors are missed in women. Symptoms of coronary artery disease and heart attack, for example, can be different in women than in men. Women are also less likely to receive the recommended treatment for certain heart conditions.

If you’re like most women, you’re probably so busy taking care of everyone else, your own well-being and health tends to fall last. But you need to make your heart’s health a priority and encourage other women to do the same.

Even though heart disease tends to strike later in life, it can happen at any age. Unfortunately, more events are happening in women younger than 50, especially Black women and Hispanic women. There are things about being a woman that can make you more prone to heart problems (for example, certain health problems during pregnancy, treatment of breast cancer, menopause and hormones).

Learn about your risk for heart disease and what you can do to lower your chance of developing it. You can help protect your heart by adopting heart-healthy habits – for example, by exercising, eating right, getting enough rest, not smoking, and focusing on your health in general.

If you already have heart disease, you’re in good company – millions of women are living with some form of heart disease, and they can provide a wealth of advice to help on your journey. Remember that prevention, early and accurate diagnosis, and treatment are critical.

Overview

When it comes to heart disease, men and women are not created equal. In whatever way you look at heart disease – the way it is best diagnosed, the symptoms, the risk factors that contribute to its progression, as well as treatments or their application – clear differences emerge based on whether you are born a woman or a man.

While efforts are underway to better understand these sex-specific differences in heart disease, today’s research is just a start.

So, if you are a woman or care for one, listen up. Arming yourself with knowledge about your risk is important. Coronary heart disease is not just a “man’s disease,” and its effect on women tends to be riddled with misunderstandings. While deaths related to coronary artery disease – known as CAD for short – are declining overall, rates are increasing in young women.

To put it into context, more women have died from heart disease than all cancers combined. All told, heart disease claims the lives of 1 out of 3 women in the U.S. each year.

What is coronary artery disease?

Coronary artery disease is the most common type of heart disease. It develops when your coronary arteries, which act like fuel lines to supply blood and oxygen to the heart, become damaged or diseased. This often results when plaque or atherosclerosis builds up in the walls of the arteries.

When your coronary arteries become narrowed or blocked, it limits blood flow to the heart. In some cases, the plaque can rupture, and blood flow is abruptly reduced and completely blocked. CAD can lead to:

• Chest pain (angina)
• Heart attack
• Heart failure
• Heart rhythm problems

CAD in women

In women more often than men, these things can occur even without evidence of any obstructive coronary artery disease. This may be because the small vessels of the arteries are not responding normally. This makes the diagnosis and treatment in women challenging.

Women are just as likely as men to develop CAD. Diabetes is the strongest risk factor in women. In fact, studies suggest diabetes more than triples the chance of CAD in women, compared with doubling the chance for men.

In women, CAD usually develops seven to 10 years later in life compared with men. Menopause seems to trigger a host of risk factors including:

• Weight gain, especially carrying excess fat around your waist or midsection
• Higher blood pressure
• Unfavorable changes in cholesterol levels (rise in LDL and triglycerides, fall in HDL)

Heart attack in women

When women experience symptoms of a heart attack, women tend to:

• Experience many other symptoms in addition to chest pain or chest pressure
• Have no overt signs of blockages in the three major coronary arteries on tests, although blood flow to the heart muscle is reduced
• Have diffuse blockages or vascular dysfunction in smaller arteries (men are more likely to have plaque buildup in the large arteries around the heart)
• Be treated less aggressively with guideline-recommended therapies than men
• Be less likely to dial 911 when they experience symptoms of a heart attack