A 5-year-old Brookfield girl who died suddenly in September was suffering from a heart condition, according to an autopsy performed by the Cook County Medical Examiner.

Kelly Nguyen died from dilated cardiomyopathy and myocarditis, according to a spokeswoman from the medical examiner’s office. Nguyen was a kindergarten student at Lincoln School in Brookfield.

Dilated cardiomyopathy is a condition which can exhibit itself in people of all ages and the cause is often unknown, according to the Cleveland Clinic Web site. It decreases the heart’s ability to pump blood and those suffering from it exhibit few symptoms or develop them as the condition gets worse.

While the cause is unknown in most cases, according to the Cleveland Clinic site, it can be passed on through heredity or brought on by a viral illness among other things.

Myocarditis, which was listed as a contributing cause in Nguyen’s death, is the inflammation of the heart muscle.

Nguyen died at 4 a.m. on Sept. 24 at Loyola University Medical Center. On Monday, Sept. 21, she had been kept home from school because she felt ill. She was back in school on Tuesday, but was taken to the doctor by her family on Sept. 23. She was sent home from the doctor that afternoon, but ended up at the hospital at 1 a.m. on Sept. 24, dying hours later.

At the time of Nguyen’s death, Lincoln School Principal Kathrine McCarthy offered to create a memorial at the school if the family desired. However, she said, the family declined.

“The family told me that our support was enough to help Kelly’s spirit live on,” McCarthy said.