She represented the United States at the 1984 Summer Olympics in Los Angeles, California, placing fourth in the finals of the 400-meter Individual Medley.

[3] Sue swam for Abington Heights High School, where she broke records in freestyle, breaststroke, backstroke, and individual medley.

[4][5] In August of 1979, Sue took two gold medals in the Junior Long Course Swim Championships in California, setting age group records in the 200 and 400 IM.

[4][6] Heon swam for the University of Pittsburgh under Coaches Dick Bradshaw and his successor Dave Belowich[7] on a full swimming scholarship, from 1981-1985, setting seven school records.

[9] She earned her first medal in international competition, a gold, in the women's 400-meter individual medley on August 27, 1982 at the U.S.-Russia Dual meet at the University of Tennessee in Knoxville.

[4][9] At the 1984 Los Angeles Olympics, where she was coached by Hall of Fame Coach Mark Schubert of California's Mission Viejo Nadadores Swim Club,[4] she won her heat in the preliminaries, but finished fourth with a 4:49.5 in the final event of the women's 400-meter individual medley, about three seconds slower than her time at the Olympic trials.

[12] After College and swimming competition, Heon worked as an elementary school teacher, teaching mostly fourth grade, and living near the San Francisco Bay Area with husband Jim Preston, an athlete and Ironman triathlete competitor, and their two children.