Medtronic Inc has confirmed that it had received a warning letter from U.S. health regulators calling for corrective actions based on an inspection of its Mounds View, Minnesota, facility, the headquarters of its cardiac rhythm management (CRM) business, the company’s largest unit. The letter from the Food and Drug Administration comes in the wake of problems Medtronic has had with its leads that are used with implantable cardioverter defibrillators, known as ICDs.