Actually, I believe I answered it in the first sentence. If a person is correctly diagnosed with bipolar disorder, there is not much that can be predicted about response to EMDR that is much different from any other general predictions. I wouldn't expect EMDR to impact bipolar disorder much.

General information about responses to EMDR may be found in the book by Shapiro and Forrest EMDR: The Breakthrough Therapy to Anxiety, Stress and Trauma.