In August 2014, Danville, Ohio, resident Mandy Holt went to an auction for a coworker, who was selling her household items. Holt, a surgical nurse at Knox Community Hospital, had a cookie and shortly afterward began having what she first thought was ordinary heartburn. But when the pain began intensifying within about 15 minutes— spreading to her back, jaw and down her arms— and she started to feel nauseous, she knew something was wrong.

Holt, who was 38 at the time, was suffering from spontaneous coronary artery dissection (SCAD), a type of heart attack that’s on the rise among women in their 30s, 40s and 50s.

“I never would have dreamt in a million years that it would happen to me, and it did,” Holt, who had no prior health issues nor a family history of cardiac problems, told FoxNews.com. “People need to be aware that it can happen whether you’re 25, or 30, or 50 or 60. It’s important to know the signs and symptoms of a heart attack, and get help.”

Experts familiar with SCAD say Holt is lucky because many women who present symptoms of the condition get turned away from the emergency room. Often, doctors simply don’t think they’re having a heart attack and misdiagnose the condition with anxiety, a gallbladder problem, or a previously reported medical issue on the patient’s record.

It’s for precisely those reasons that researchers say instances of SCAD have historically been underreported, preventing scientists from knowing exactly how prevalent the disease is. But due to grassroots efforts to better educate clinicians about SCAD, and a growing number of hospital registries that track this patient population, more cases are slowly coming to light.

Seeking a diagnosis in the absence of risk factors

SCAD isn’t the same as an atherosclerotic heart attack, best known as coronary artery disease— the type that accounts for one in four annual U.S. deaths and is the leading cause of death in the country. Coronary artery disease is marked by the buildup of plaque, and can be caused by high cholesterol or high blood pressure. SCAD patients don’t have those hallmarks for heart attack—  rather, precipitating risk factors for the disease are lifting heavy things, having violent coughing or wrenching, undergoing extreme emotional stress, or having connective tissue issues or vascular issues.

The top risk factor for the condition, however, is being a woman— experts estimate that anywhere from 80 to as much as 90 percent of reported SCAD patients are female.

Many of the women who undergo SCAD are young and fit, as are the smaller portion of men.

“Unfortunately, it doesn’t look like there’s anything that women are doing to themselves for risk factors, which is what makes this scary,” Holt’s doctor Esther Kim, a staff physician in cardiovascular medicine at the Cleveland Clinic, told FoxNews.com.

During atherosclerosis, a buildup of substance, including cholesterol, causes the coronary artery to become blocked. A heart attack occurs when the plaque ruptures then spills into the bloodstream, forming a clot at the site of the event, and when this clot is big enough, it halts blood from flowing through the coronary artery. But during SCAD, Kim said, a mysterious event causes a tear in the artery, separating different cellular layers that help maintain artery function.  Blood then can travel down a newly created passageway and push the innermost layer against the side of the wall and artery, causing abrupt occlusion. The artery then falls in on itself because of the tear and causes a blockage of blood.

Most angiographers can recognize dissections on scans, but that there are two types of SCAD can complicate making a diagnosis, Kim said. One type can look like plaque that is isolated to one vessel, which often is misdiagnosed as atherosclerosis in women without high blood pressure and cholesterol, but the most common type is marked by an abrupt narrowing in the artery.

“Because it’s women, there’s always a theory about the hormonal basis,” Kim said. “We haven’t been able to elucidate this connection. This is similar to other diseases. Fibromuscular dysplasia (FMD) and lupus: Why do these affect women more?”

Coping with SCAD’s unique consequences

Doctors originally thought SCAD was most prevalent among pregnant women in the last week of pregnancy and the first week following birth, but improved reporting has led to an observance of SCAD among women who are postmenopausal and those who have regular menstruation too, Kim said.

Katherine Leon, of Alexandria, Virginia, had her heart attack about seven weeks after having her second son, at which point she experienced all the classic signs of heart attack. But she was only diagnosed with SCAD after going to the ER two times. During her first visit, doctors pointed to Leon’s only previous health issue, asthma, and advised her to get her gallbladder checked instead of suspecting a heart attack.  Prior to her second visit, she was bathing her child and headed back to the ER because her chest pain became unbearable.

“I had two kids under 2, and I was getting blown off left and right, so I felt horrible for five weeks,” Leon, who is now 50, told FoxNews.com. “I had these severe heart attack symptoms at the end of April [2003], and took two trips to the ER, and finally had a heart catheterization, and went straight to the OR and had double bypass surgery. I was 38.”

Now, Leon has dedicated her life to raising awareness of SCAD in hopes of preventing her story from happening to other women. In 2013, she co-founded the SCAD Alliance, which aims to educate medical professionals on how to better diagnose and treat SCAD with the help of a scientific advisory board, as well as offer support for women coping with the psychosocial effects of the condition.

Because women who undergo SCAD often are still of childbearing age, their challenges are unique compared to those of the traditional heart attack patient, who may experience the event later in life after she raises her children or has begun to undergo other health problems that can come with older age.

For example, one patient whom Leon counseled had run a 10K race the week before having SCAD, so she was reluctant and offended to attend her doctor’s prescribed cardiac rehab, a first-line therapy for SCAD in addition to medication, Kim said.  

“That’s a tough one,” Leon pointed out, “because you don’t want to diminish what they’ve done, [and] you don’t want to make them feel like the 10K is what caused it. It’s all complicated.”

Searching for an evasive cause

In the SCAD Alliance’s first research effort, Leon collaborated with Dr. Sharonne N. Hayes, a cardiologist and the founder of the Women’s Heart Clinic at the Mayo Clinic, in Rochester, Minn., who would later try to identify genetic risk factors for the disease. Hayes is one of three researchers worldwide who is consistently studying SCAD. The others are Dr. Fernando Alfonso at the Universidad Complutense in Spain and Dr. Jacqueline Saw from the University of British Columbia in Vancouver.

Hayes and her team initially thought to seek out a genetic link to the disease because conditions like Marfan syndrome and some types of Ehlers-Danlo syndrome are marked by a genetic mutation yet are associated with blood vessel dissection. For their preliminary results, which were reported in the May edition of JAMA Internal Medicine, study authors did not identify any one gene for SCAD, but they did find a handful of candidate genes associated with the disease.

“This is going to be a more complicated genetic exploration,” Hayes told FoxNews.com. “There’s not going to be a single SCAD gene— some may be de  novo mutations, meaning it occurred in a family member and wasn’t inherited.”

Hayes and her team studied the angiograms and conducted surveys among 412 SCAD patients in the Mayo Clinic’s retrospective registry, which today has grown to 500 people with an average age of 42. The registry is still growing and collects data from patients online from all over the world. The Mayo Clinic and the Cleveland Clinic are two among a growing number of hospitals in the United States that have started registries in hopes that more data on SCAD may lead researchers to answers.

“Some of the things that we have observed is patients who have SCAD are different from patients with atherosclerotic heart disease,” Hayes said. “It’s not just age; it’s also abnormalities in their blood vessels—it’s [those who’ve had] fibromuscular dysplasia and those who have other aneurysms and dissections of the blood vessels.”

Next, Hayes said her team’s goal is to gather enough funding to exome sequence SCAD participants in the Mayo Clinic’s registry to further analyze genetic mutations among this patient population.

She and her colleagues also published a review article for the Mayo Clinic this month that compiles previous SCAD research results, and aims to facilitate clinicians’ diagnoses of SCAD in doctors’ offices, hospitals and the ER.

“This is a charge to we, as researchers and in the medical community, to keep working hard and to call for better funding of heart disease cases in young women, which are generally underfunded,” said Hayes, who noted that although SCAD is seen as rare, it appears to be the No. 1 type of heart attack among women under 40.

Facing the unknown

According to the Mayo Clinic, SCAD patients tend to fare better than atherosclerotic patients in terms of survival. The average SCAD patient usually returns to a normal life after heart attack, albeit with a prescription for cardiac rehab and a cocktail of drugs.

Holt, the Cleveland Clinic patient, spent a few days in the hospital and hasn’t had another SCAD incident since her first. She did cardiac rehab every day for 12 weeks, and ever since SCAD has regularly taken three medications— Plavix to prevent the arteries from becoming clogged; Isosorbide to prevent angina, a common after-effect of the heart attack; and a baby aspirin.

Holt has resumed working as a nurse and tending to her family’s 20-acre farm in Danville, where she and her husband, Jeffrey, and their children— Emily, 15, Ethan, 11, and Elliott, 7— raise pigs. But following SCAD, she dealt with anxiety induced by Googling SCAD symptoms out of fear she may have another heart attack. Holt saw a therapist, and turned to her family and church for comfort.

Kim, Holt’s doctor, said figuring out the recurrence rate of SCAD is “the million-dollar question”—with older data suggesting it could be as high as 30 percent in 10 years and newer data suggesting it’s 27 percent in five years. Perhaps the largest challenge for SCAD patients, experts and patients say, is living with the fear of not knowing when another heart attack may strike.

“I have never had any issues health-wise, and for this to happen was a real shock for me,” Holt said. “If you ask me today to rate my health, I would say, ‘I don’t know’ because it’s that fear of the unknown. I don’t know what caused it to happen; nobody knows what caused it to happen, and can it happen again?”