How can I search for epics that have a testrail result associated with them

[Moira Tuffs]

We have testrail linked into our Jira such that when a testcase is run that references a jira item, the testrail section in Jira shows the result under the 

Testrail: Results

How can I create a filter for the epics that have a testrail result from Jira ?

Thanks in advance for your help

Moira