On May 23, 2005 — Lefthander Mark Mulder of the St. Louis Cardinals becomes just the 12th National League pitcher since 1976 to throw a complete game shutout of 10 innings or more when he blanks the Houston Astros, 1 – 0, in 10 innings. Greg Maddux posted the last extra-inning shutout in the National League in 1988.
Source:
Baseball Reference May 23