The life of Rose of Viterbo might have been short, but it was eventful enough to end with her on the path to sainthood. Since her death in the year 1252, most believed that St. Rose died of tuberculosis. But a new autopsy of her mummified heart shows that cardiac problems, not disease, ended the life of this Medieval saint.

A team of researchers X-rayed the teen mummy's heart, revealing a blockage that probably caused a heart attack. Additionally, genetic analysis of her body and hair show no signs of tuberculosis.

"The X-ray revealed the presence of a particular defect, a mass, that we think was the cause of death," said Ruggero D’Anastasio, a professor in the Human Movement Sciences Department of State University "G d'Annunzio," in Chieti, Italy.

The autopsy was possible thanks to the amazing preservation of Saint Rose's body.

Shortly after she died, monks at the monastery in Viterbo, Italy, interred the body in a glass reliquary, in anticipation of her pending canonization. The glass box they sealed her in kept out moisture and oxygen, and sustained a constant temperature, allowing the corpse to desiccate into a natural mummy.

"The body is well-preserved. It's a natural mummy, but perfectly preserved," D'Anastasio told LiveScience.

In 1921, a priest removed the heart from Saint Rose’s body to create another relic. Then, earlier this year, the church in Viterbo commissioned the local university to survey the condition of the relics, so that the church could better preserve them.

D'Anastasio and his team did that appraisal, and discovered the blockage in the heart while looking at an X-ray. The blockage is an embolism, or blood clot that had travelled from another part of her body, that eventually lodged itself in her heart. 

The examination also determined Rose's age, allowing the church to pinpoint the date of her birth for the first time. Turns out, when the fatal embolism killed Saint Rose, she was only 18 or 19 years old.

The results are detailed in the June 11 issue of the journal the Lancet.