How can I filter pull requests that are not yet approved

Question

I'd like to see a list of pull requests that I'm assigned to review that are not yet approved.

I can see using the filter box which PR's I'm assigned to with

is:open is:pr assignee:MyId

what can I add to reduce the list of PRs to those not yet approved? Does new approval review feature have a field name I can filter on and pair with 'NOT'?

Answer 1

Dec 2016: That does not seem to be available
Update February 2017: The approved status is now part of the search criteria.

Filter pull requests that a reviewer has approved: state:open type:pr review:approved

You can search based on the state of an issue or pull request:

You can filter pull requests based their review status (none, required, approved, changes requested, or required), by reviewer, and by requested reviewer.

type:pr review:approved: will Match pull requests that a reviewer has approved.

See "Filter pull request reviews and review requests" (January 23d, 2017)

To make it easier to find the pull requests that need your attention, you can now filter by review status from your repository pull request index.

Note though that the Pull Request API does not mentioned an approved state.
Nor does the List reactions for a pull request review comment.