Following a heart attack sometimes part of the muscle gets so badly damaged that it is replaced by hard rough fibrous tissue which does not contract and leads to formation of blood clots on its inner surface. These blood clots can dislodge and travel to the brain causing serious strokes and sometimes death.

Pieces of clot removed from the heart in the previous picture.

Following removal of clots and excision of aneurysm the normal muscle of the heart is stitched together.