Question special

In the combination alteplase-thrombectomy arm, 31 of 329 (~10%) patients did not receive thrombectomy. 17 of these were due to thrombus migration or dissolution.
-- Were migration or dissolution events more common?
-- Was there a signal that this was due to longer alteplase time causing clot migration/dissolution?
-- What effect do you think this had on the primary outcome?
Thank you for your time!