Kara Kennedy, Ted Kennedy's Daughter, Dies at 51
09/17/2011 AT 02:00 PM EDT
She was working out in a Washington D.C.-area gym at the time, the Associated Press reports.
"She's with dad," Patrick Kennedy said. Their father died in 2009 at age 77 after battling a brain tumor.
Kara, who helped work on her father's senatorial campaign, was also a cancer survivor. In 2003, she had a malignant tumor removed from her lungs. According to her brother Patrick, the cancer treatment "took quite a toll on her and weakened her physically. Her heart gave out."
Kara, who was divorced, is survived by her two teenage children.