As you know, blood is a kind of liquid, while blood clots are solid matter. The conversion from blood to blood clots is the transformation from something liquid to solid matter.
In an AFib patient’s heart, his blood pools there and it becomes thicker and thicker gradually. Finally blood clots are formed in his atria. With the assistance of blood circulation, these bloods clots can be transported in blood vessels to any part of the body. If they don’t fall apart, they can be dangerous and lead to serious medical conditions, like stroke.