 Ritvo developed cardiomyopathy, which had killed her brother Louis at the age of 38, as well as her father at age 73. She had been plagued by unusual fatigue since 1998, and her heart condition was formally diagnosed in January, 2001. She began taking medication and trained on a limited basis from 2003 to 2005, starting about 100 horses in that period, with 15 wins. However, her condition deteriorated. She started only one horse in 2005 and had no starters from 2006 until 2009. In 2008, at the age of 39, she was placed on a waiting list for a heart transplant. After a seven-month wait, an organ became available on November 13, 2008, and Ritvo received her new heart that day in an operation that lasted 17 hours. She had been hospitalized for most of the previous six months, and at the time of her surgery her doctors assessed her as having only about two weeks to live. She was discharged from the hospital seven days after her surgery. She later gave a letter to the hospital to pass on to the organ donor's family, but has never heard from them. Ritvo has stated that she wants the donor's family to know she is thankful for her new heart, but respects their privacy.
