The woman, Joanie Simpson, told the Washington Post she recently lost her 9-year-old Yorkshire terrier, Meha.
"I was close to inconsolable," Simpson told the Post. "I really took it really, really hard."
Broken heart syndrome, also known as stress cardiomyopathy, can be misdiagnosed as a heart attack because test results and symptoms are similar, according to the American Heart Association.
The key difference: There's no evidence of blocked arteries in someone with broken heart syndrome. Researchers found Simpson's coronary arteries were normal.
Women are more likely than men to suffer from broken heart syndrome. Harvard Medical School said more than 90 percent of reported cases involve women ages 58-75.