Story highlights CNN investigation calculates that from 2011 to 2013, the program mortality rate is more than three times the national average

St. Mary's CEO Davide Carbone says CNN is wrong, does not say what hospital thinks correct rate is

(CNN) A baby who had heart surgery at St. Mary's Medical Center in Florida died Tuesday, at least the ninth infant to pass away after such a procedure since the program opened at the end of 2011.

A CNN investigation calculates that from 2011 to 2013, the program had a 12.5% mortality rate for open heart surgeries, which is more than three times the national average.

"Why won't they stop?" asked Nneka Campbell, whose baby daughter, Amelia, died after heart surgery at the hospital.

The same day the latest baby died, St. Mary's CEO Davide Carbone wrote a letter to employees about the CNN investigation, which aired Monday night, expressing support for the program and its heart surgeon, Dr. Michael Black.

"The patients we serve are afflicted with severe life-threatening conditions, and it is impossible to eliminate the risk of mortality," he wrote.

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