Heart attacks don’t always strike out of the blue — there are many symptoms we can watch for in the days and weeks leading up to an attack. but the symptoms may not be the ones we expect. And they can be different in men and women, and different still in older adults. Last year, for example, a landmark study by the National Institutes of Health (NIH) published in Circulation: Journal of the American Heart Institute found that 95 percent of women who’d had heart attacks reported experiencing symptoms in the weeks and months before the attack — but the symptoms weren’t the expected chest pain, so they went unrecognized.

Don’t let that happen to you. here, 10 heart symptoms you’re likely to ignore — and shouldn’t.

1. Indigestion or nausea

One of the most oft-overlooked signs of a heart attack is nausea and stomach pain. Symptoms can range from mild indigestion to severe nausea, cramping, and vomiting. others experience a cramping-style ache in the upper belly. Women and adults over age 60 are more likely to experience this symptom and not recognize it as tied to cardiac health.

Most cases of stomach ache and nausea aren’t caused by a heart attack, of course. but watch out for this sign by becoming familiar with your own digestive habits; pay attention when anything seems out of the ordinary, particularly if it comes on suddenly and you haven’t been exposed to stomach flu and haven’t eaten anything out of the ordinary.

2. Jaw, ear, neck, or shoulder pain

A sharp pain and numbness in the chest, shoulder, and arm is an indicator of heart attack, but many people don’t experience heart attack pain this way at all. Instead, they may feel pain in the neck or shoulder area, or it may feel like it’s running along the jaw and up by the ear. some women specifically report feeling the pain between their shoulder blades.

A telltale sign: The pain comes and goes, rather than persisting unrelieved, as a pulled muscle would. this can make the pain both easy to overlook and difficult to pinpoint. you may notice pain in your neck one day, none the next day, then after that it might have moved to your ear and jaw. if you notice pain that seems to move or radiate upwards and out, this is important to bring to your doctor’s attention.

3. Sexual dysfunction

Having trouble achieving or keeping erections is common in men with coronary artery disease, but they may not make the connection. Just as arteries around the heart can narrow and harden, so can those that supply the penis — and because those arteries are smaller, they may show damage sooner. One survey of European men being treated for cardiovascular disease found that two out of three had suffered from erectile dysfunction before they were ever diagnosed with heart trouble.

4. Exhaustion or fatigue

A sense of crushing fatigue that lasts for several days is another sign of heart trouble that’s all too often overlooked or explained away. Women, in particular, often look back after a heart attack and mention this symptom. More than 70 percent of women in last year’s NIH study, for example, reported extreme fatigue in the weeks or months prior to their heart attack.

The key here is that the fatigue is unusually strong — not the kind of tiredness you can power through but the kind that lays you flat out in bed. if you’re normally a fairly energetic person and suddenly feel sidelined by fatigue, a call to your doctor is in order.

5. Breathlessness and dizziness

When your heart isn’t getting enough blood, it also isn’t getting enough oxygen. And when there’s not enough oxygen circulating in your blood, the result is feeling unable to draw a deep, satisfying breath — the same feeling you get when you’re at high elevation. Additional symptoms can be light-headedness and dizziness. but sadly, people don’t attribute this symptom to heart disease, because they associate breathing with the lungs, not the heart.

In last year’s NIH study, more than 40 percent of women heart attack victims remembered experiencing this symptom. a common description of the feeling: “I couldn’t catch my breath while walking up the driveway.”

6. Leg swelling or pain

When the heart muscle isn’t functioning properly, waste products aren’t carried away from tissues by the blood, and the result can be edema, or swelling caused by fluid retention. Edema usually starts in the feet, ankles, and legs because they’re furthest from the heart, where circulation is poorer. In addition, when tissues don’t get enough blood, it can lead to a painful condition called ischemia. Bring swelling and pain to the attention of your doctor.

7. Sleeplessness, insomnia, and anxiety

This is an odd one doctors can’t yet explain. Those who’ve had heart attacks often remember experiencing a sudden, unexplained inability to fall asleep or stay asleep during the month or weeks before their heart attack. (Note: if you already experience insomnia regularly, this symptom can be hard to distinguish.)

Patients often report the feeling as one of being “keyed up” and wound tight; they remember lying in bed with racing thoughts and sometimes a racing heart. In the NIH report, many of the women surveyed reported feeling a sense of “impending doom,” as if a disaster were about to occur. if you don’t normally have trouble sleeping and begin to experience acute insomnia and anxiety for unexplained reasons, speak with your doctor.

8. Flu-like symptoms

Clammy, sweaty skin, along with feeling light-headed, fatigued, and weak, leads some people to believe they’re coming down with the flu when, in fact, they’re having a heart attack. even the feeling of heaviness or pressure in the chest — typical of some people’s experience in a heart attack — may be confused with having a chest cold or the flu.

If you experience severe flu-like symptoms that don’t quite add up to the flu (no high temperature, for example), call your doctor or advice nurse to talk it over. Watch out also for persistent wheezing or chronic coughing that doesn’t resolve itself; that can be a sign of heart disease, experts say. Patients sometimes attribute these symptoms to a cold or flu, asthma, or lung disease when what’s happening is that poor circulation is causing fluid to accumulate in the lungs.

9. Rapid-fire pulse or heart rate

One little-known symptom that sometimes predates a heart attack is known as ventricular tachycardia, more commonly described as rapid and irregular pulse and heart rate. during these episodes, which come on suddenly, you feel as if your heart is beating very fast and hard, like you just ran up a hill — except you didn’t. “I’d look down and I could actually see my heart pounding,” one person recalled. It can last just a few seconds or longer; if longer, you may also notice dizziness and weakness.

Some patients confuse these episodes with panic attacks. Rapid pulse and heartbeat that aren’t brought on by exertion always signal an issue to bring to your doctor’s attention.

10. you just don’t feel like yourself

Heart attacks in older adults (especially those in their 80s and beyond, or in those who have dementia or multiple health conditions), can mimic many other conditions. but an overall theme heard from those whose loved ones suffered heart attacks is that in the days leading up to and after a cardiac event, they “just didn’t seem like themselves.”

A good rule of thumb, experts say, is to watch for clusters of symptoms that come on all at once and aren’t typical of your normal experience. For example, a normally alert, energetic person suddenly begins to have muddled thinking, memory loss, deep fatigue, and a sense of being “out of it.” The underlying cause could be something as simple as a urinary tract infection, but it could also be a heart attack. if your body is doing unusual things and you just don’t feel “right,” don’t wait. See a doctor and ask for a thorough work-up.

And if you have any risk factors for cardiac disease, such as high blood pressure, high cholesterol, smoking, or family history of heart disease, make sure the doctor knows about those issues, too.