Extreme stress can trigger what seems to be a heart attack, but is really something known as “broken heart” syndrome, researchers said on Wednesday as they cautioned doctors to know the difference.

Unlike conventional heart attacks stemming from blocked arteries, broken heart syndrome, or stress cardiomyopathy, is caused by an extended surge in adrenaline, such as after a car crash or even learning of the death of a loved one.

It may only require short-term treatment because the heart usually recovers by itself.

In a study published in this week’s edition of The New England Journal of Medicine, researchers led by Ilan Wittstein of Johns Hopkins University School of Medicine in Baltimore found some people may respond to sudden, overwhelming emotional stress by releasing large amounts of adrenaline and other chemicals into the blood stream.

These chemicals can be temporarily toxic to the heart, effectively stunning the muscle and producing symptoms similar to those of a typical heart attack: chest pain, fluid in the lungs, shortness of breath and heart failure.

But the similarities end there. Closer inspection using blood tests and magnetic resonance imaging scans failed to show the typical heart attack signs, such as irreversible muscle damage and elevated levels of certain enzymes.

Wittstein said being able to recognize broken heart syndrome in patients has helped his team avoid “incredibly invasive procedures.”

He cited the case of a 27-year-old who developed severe shock with very low blood pressure after hearing tragic news. She appeared near death and surgeons were prepared to implant a mechanical pump in her chest.

But the operation was delayed when doctors recognized the telltale signs of broken heart syndrome.

“Not only did she not require the open heart surgery, she was discharged from the hospital three days later and has regained completely normal heart muscle function,” Wittstein told Reuters.

He cautioned that even a stress-induced heart attack can’t go untreated. There may be underlying heart disease that must be addressed, and the symptoms of broken heart syndrome, if severe enough, must be dealt with quickly.

“If a person’s condition is very unstable, you need to treat the instability,” he said. Three of the 19 patients in the study temporarily required a special balloon to be implanted in the aorta to help the heart pump better.

The researchers plan to study whether certain patients have a genetic vulnerability for the condition, and why it predominantly strikes older women.