Before one can understand how heart problems can cause a brain attack, one must understand how blood clots. As previously stated, platelets cause blood clots by sticking to bumpy surfaces on damaged arteries.
Clotting factors cause blood clots in a different way.
They are chemicals that stay dissolved in blood as long as the blood continues to flow rapidly. Clotting factors act very much like powdered gelatin. If you blend gelatin powder with water and stir the mixture continuously and rapidly, the gelatin will stay in liquid form and not harden. If, however, you stop stirring the mixture and allow it to remain still, it will eventually form hardened gelatin. This property is very useful for stopping the bleeding due to a cut because the blood flow in the area of the cut is usually slower than in the arteries.