The claim that Loretta had told them over Thanksgiving dinner that "she had some kind of irregular heartbeat" "that she planned to get [] checked out" is a mighty convenient recollection!
Their statement was made on December 30th, 2013 and his was made after the autopsy was released in January of 2014.
What Loretta Fuddy told her brother about her medical history is unknown to us. We do not know what the dynamics of that family were. Maybe she only confided medical stuff to her sister. We don’t know.
But the fact remains shortly after the accident her family did tell investigators that she said she had a had an irregular heartbeat.
If you choose to discount the sister’s earlier statements to investigators - feel free to pick and choose whatever facts you need to confirm your theories.