There's long been a belief that heart disease is primary a man's disease - even as evidence has emerged that it is the number one killer of women.

New research published Monday suggests that this inaccurate assumption can be extremely dangerous for women.

One study found that even when younger women - those under 55 - had similar or greater risks for heart disease than their male counterparts (due to high cholesterol or diabetes, for example), they were less likely to be told by doctors and other health-care providers about those risks before a heart attack.

And when younger women arrived at the hospital suffering from the deadliest form of heart attack, they were less likely to receive a life-saving procedure to open clogged heart arteries and more likely to die in the hospital than their male counterparts.

Both studies were published in the Journal of the American College of Cardiology.

In the first study, researchers analyzed medical records of and interviewed 3,501 heart attack patients from more than 100 hospitals in the United States and Spain between 2008 and 2012. The study included patients who were 18 to 55 years old. About two-thirds were women.

Nearly all patients had at least one of the five cardiac risk factors: diabetes, high cholesterol, hypertension, obesity and smoking.

But women were 11 percent less likely than men to report being told they were at risk for heart disease before their heart attack and 16 percent less likely to say they talked with a clinician about ways to reduce that risk.

Erica Leifheit-Limson, the study's lead author and an epidemiologist at the Yale School of Public Health, said researchers aren't sure why this is happening. It's possible that preventive efforts may be more focused on men because of the belief that heart disease affects them more. It's also possible that preventive efforts directed toward women aren't being communicated effectively.

Whatever the reason, "young women cannot afford to be continually less informed than men about their risk for heart disease," she said.

The second study highlights the deadly consequences from the gender gap in heart attack care.

When it comes to providing angioplasty and stents to restore blood flow in blocked arteries of women having the deadliest form of heart attacks, researchers found there isn't the same level of vigilance as compared to men.

This type of heart attack, known as ST-elevation myocardial infarction, is caused by a 100 percent blockage of blood supply in the heart. Patients recover most successfully when doctors insert and inflate a tiny balloon to unclog and widen the artery. That procedure is often combined with the placement of a small wire mesh tube called a stent to help prop the artery open and decrease its chance of narrowing again.

Researchers analyzed more than 630,000 patients between the ages of 18 and 59 years who had this kind of heart attack from 2004 to 2011. Women were less likely to have complained or described symptoms and less likely to receive angioplasty and stenting, they found.

That may be one reason why women died in the hospital at a higher rate than their male counterparts; 4.5 percent of women in the study died in the hospital compared to 3 percent of men. Women were also hospitalized for slightly longer: on average, 4.35 days versus four days.

Again, researchers don't know why women are less likely to receive angioplasty and stenting.

They're not sure whether there's a biological difference in men and women suffering heart attacks, or a difference in the way men and women report their symptoms, or how doctors and nurses interpret that information, said Deepak Bhatt, senior author of the second study and executive director of interventional cardiovascular programs at Brigham and Women's Hospital in Boston.

If someone having a heart attack arrives at the hospital complaining of fatigue and shortness of breath instead of crushing chest pain, that may delay care or lead to a misdiagnosis, he said. Experts say women are somewhat more likely than men to experience some of the other common symptoms, especially shortness of breath, nausea/vomiting and back or jaw pain.

Some experts have speculated that women may be more likely to delay seeking care because they're don't want to inconvenience others.

"We can't say where the fault lies," he said. "I don't think it's any one thing."

Here are some heart attack signs in women from the American Heart Association:

1. Uncomfortable pressure, squeezing, fullness or pain in the center of your chest that last more than a few minutes, or goes away and comes back.

2. Pain or discomfort in one or both arms, the back, neck, jaw or stomach.

3. Shortness of breath with or without chest discomfort.

4. Breaking out in a cold sweat, nausea or lightheadedness.