It was a heart attack that stopped the show at the Goodman Theater last week. The Goodman’s artistic director Robert Falls says a mild heart attack struck 76-year-old actor Stacy Keach during the opening night performance of the play, “Pamplona” last week. Keach tried to continue delivering his lines in the one-man show about Ernest Hemingway but couldn’t, and the show was halted. Keach spent the next week in the hospital and is expected to make a full recovery, but the rest of the play’s run has been cancelled. Falls says it probably can’t be rescheduled until sometime next year.