The Signal Interview When David Cordani hands over the title of Cigna CEO to Brian Evanko on July 1, the triathlete will be ending the longest leadership run of any of his industry peers. In his 17 years in charge, the US health insurer’s annual revenues expanded from $18 billion to $275 billion, as its customer base grew from 40 million people to 180 million.Cordani will be sticking around, keeping oversight of his company’s thorny government r…