The 50-year-old actress - who was previously married to Motley Crue drummer Tommy Lee and Bon Jovi rocker Richie Sambora - announced she was to marry her `Melrose Place` co-star Jack Wagner three months ago, but the pair have now backtracked on their plans.
A spokesperson for Heather told Usmagazine.com: "Jack and Heather are no longer engaged."
It is not clear why Jack and Heather - who began dating in 2007 - have ended their engagement.
Speculation their relationship was in trouble was rife when the actress arrived alone at the `Twilight Saga: Breaking Dawn Part I` premiere and was not wearing her engagement ring.
Jack is best known for playing a sea captain on long-running US TV show `The Bold and the Beautiful`, while Heather is currently working on `The Assistants` alongside David Henrie.
The blonde beauty has had a turbulent few years - last year she was arrested, and later cleared for, a hit-and-run accident after hitting a No Parking sign in Ventura County, California, and in 2008 she entered rehab seeking treatment for anxiety and depression.