"Is it possible that they moved the FA to a higher number of events because the data was very robust. If the number of events for the FA was increased to 75% and that number of events was not expected to be achieved until end of Jan or Feb 2018, then it would be so close to the end of recruiting that it would not make sense to stop the trial early."

If the data was so robust, why would they not still announce a passed futility analysis at 50% of events as originally planned? They can always stop the trial early at a later point in time (hopefully for good reasons) since there are more period DSMB reviews throughout the trial. I recall there already was a plan to do a sample size estimate analysis at 175 events. So they could have done both: announce futility analysis at 50% of events and still terminate early for good reasons at a later point.

As for a revised futility analysis occuring at 75% of events (around Q1 2018 as you suggest) coinciding with the H1 2018 end of recruitment......to me it would not make much sense to go through all the trouble of seeking FDA involvement and starting to recruit US patients only to prematurely end the trial after the newly enrolled USA patients have been on drug for at most a few months. We really need to know more details like what changes to BETonMACE (# patients, # target MACE events, lenght of trial, minimum dosing period, maximum dosing period, etc), as well as details regarding the timing of the futility analysis to make much sense of things.  

BearDownAZ