She is the last person you would expect to have a heart attack.

A slim, active 62-year-old, my friend eats healthful food, makes and skis her own trails, mows her yard and works a satisfying job managing a gift shop.

Yet during a brief visit with co-workers on her way through Caribou on her day off, she began to feel odd sensations in her jaw and arm followed by mild nausea and profuse sweating.

“This is not right,” she thought. “This is not me.”

In moments, she was on the floor, drifting in and out of consciousness.

“I realized I could not sit on a stool,” she recalled, but did not remember that others had helped her to the floor. A customer gave her an aspirin.

A 911 call brought an ambulance in minutes. Shortly after she reached Cary Medical Center in Caribou she experienced what she would later learn is a rare emergency condition called SCAD: spontaneous coronary artery dissection.

A LifeFlight airplane flew her to Eastern Maine Medical Center in Bangor, where she underwent a heart catheterization procedure to determine exactly what had occurred.

“I never actually felt real sick,” she texted me from her hospital bed after the diagnosis. “[I] just had symptoms that were not typical for me. That was the clue there was a problem. I was totally fine one moment and not the next.”

She told all the friends who contacted her to “read about SCAD.”

When she told me her doctor had asked her to participate in a Mayo Clinic study on this rare cardiac event, I immediately contacted my niece, a cardiologist at the Mayo Clinic in Rochester, Minnesota. She said she is very familiar with SCAD and with the researchers as well.

SCAD is common among younger women, she told me, sometimes following childbirth. People who experience this kind of attack are often healthy and lacking risk factors for heart disease, such as high blood pressure and diabetes.

My friend certainly fit this profile. Though beyond childbearing years, she does all the outside work in her yard and woods (except big tractor jobs), and is committed to a gluten-free diet.

Nonetheless, she experienced a heart attack that, if not diagnosed and treated promptly, can lead to sudden death. How fortunate she was to be in Caribou when it occurred and not traversing her trails in New Sweden, where she lives.

Following her suggestion to read about SCAD, I learned that a tear inside an artery causes blood to pool between inner and outer layers of the artery. Pressure from the pooling blood trapped between the layers can lengthen the tear and form a clot, slowing or stopping blood flow to the heart.

Fortunately, no blockages formed in my friend’s arteries, and she was home from the hospital after five days. She had experienced half of the symptoms signifying a SCAD.

Others include chest pain, rapid heartbeat or fluttery feeling in the chest, shortness of breath, dizziness and unusual, extreme tiredness.

“I was beginning to think I had had two heart attacks, but that is not correct,” she said after reviewing the cardiologist’s report with her primary care provider this week. “What happened at the store was the spontaneous dissection and that caused the heart attack at the hospital.”

My niece connected me with Dr. Sharonne Hayes, principal investigator for the Mayo Clinic study, who suggested I read more at www.mayo.edu/research/SCAD.

It turns out my friend may be eligible to participate in a study that was initiated in 2010 because patients like her found each other online and convinced the Mayo Clinic there were enough of them to merit research on SCAD.

“In this day and age, to have a type of heart attack that had not been researched just seemed ridiculous,” SCAD patient Katherine Leon of Alexandria, Virginia, told National Public Radio reporter Emily Bogle for a broadcast aired on Morning Edition in May 2012. Leon began looking for other SCAD patients on the internet and eventually formed an online community through a nonprofit advocacy organization called WomenHeart: The National Coalition for Women with Heart Disease, in partnership with a company called Inspire.

Leon had collected names, ages and medical information from more than 70 women all over the world when she and another SCAD survivor, Laura Haywood-Cory of Durham, North Carolina, met cardiologist Hayes at a WomenHeart Science and Leadership symposium at the Mayo Clinic in 2009. Their conversation with Hayes led to a study employing a novel approach to research.

Through social media, SCAD survivors spread the word about research in ways the researchers cannot — in effect, they recruit each other.

“This is not investigator-initiated research. This is patient-initiated research,” Hayes told NPR.

Hayes set up a database registry allowing patients all over the world to submit information and medical records.

Working with a team that includes an interventional cardiologist and a specialist in cardiovascular genetics, her research program also uses DNA and plasma samples. The goal of the program is to advance understanding of the underlying causes and risk factors for SCAD and develop solutions for optimal diagnosis, treatment and prevention.

“Patient activism and the power of online communication has tremendous potential,”

Hayes told me this week. “We have recruited over 600 women and men in the Mayo Clinic SCAD Registry” she said, adding that although most patients are women, SCAD also strikes men.

The team also has collected more than 900 DNA samples from SCAD patients and their parents in an effort to identify inherited and spontaneous mutations that underlie SCAD.

“Our experience with the ‘SCAD ladies’ Katherine Leon and Laura Haywood-Cory and their online ‘heart sisters’ provides an example of successful patient-driven, social networking-enabled research,” Hayes wrote for a report published by Inspire (“The SCAD Ladies Stand”). “Our pilot and ongoing studies demonstrate that if a large organized group of patients self-identify and present themselves to researchers as study participants, a major barrier to rare disease research can be eliminated.”

Mayo Clinic staff say SCAD is not so much a rare condition as a severely underdiagnosed one, similar to other uncommon conditions lacking enough subjects to merit research.

“We hope that our experience with these empowered and activated women can serve as a model for other patient groups and scientists,” Hayes wrote.

SCAD was a new term to nurses on the cardiac floor in Bangor, where my friend ended up after several days in the critical care unit. She also found the meal tray lacking an important component.

“Where’s the dark chocolate?” she asked in an attempt at humor. “Everything I have read says dark chocolate is good for the heart. I can’t imagine a cardiac floor without dark chocolate.”

As she anticipated returning to work this week, my friend was still fearful it might happen again. She was willing to endure the effects of discontinuing hormone replacement therapy, which she learned might contribute to the condition.

And she was eager to convey the message: “If it does not feel normal for your body, that’s the time to call your doctor.”

Looking back, she expressed one small regret: LifeFlight used an airplane to transport her to Bangor.

“Riding in a helicopter is on my bucket list,” she said.

For more information: http://www.mayo.edu/research/documents/scad-ladies- stand-up/doc- 20113993.