NEW YORK — The Food and Drug Administration has released a sharply worded warning letter to St. Jude Medical in which it said it might soon fine or take other actions against the company for failing to address agency concerns about a widely used heart device component.

The component at issue — an electrical wire, or lead, called the Durata — connects an implanted defibrillator to a patient’s heart. In the letter, dated Jan. 10, the agency said that St. Jude had failed to address a variety of concerns about the component arising from an FDA inspection last fall of a company factory in California.