Very interesting strip. (BTW sorry about chiming if this subject is already dead.)
My initial thought was A Tach converting to, possibly, a junctional rhythm. I sent a copy of the Pt hX and the link to the strip to my old paramedic instructor, he is considered an EKG guru, His thoughts were: He would like to see other leads and from what he saw thought it was a Rapid A Fib with Ashman's.
I am definitely going to do some more research on Ashman's.
Excellent strip and subsequent discussion, definitely a learning point.