The answer to the crossword is 'TIES', which stands for 'Thrombotic Events in Ischemic Syndromes'. Thrombotic events are a type of cardiovascular disease that can cause sudden death due to a blockage in the arteries. They are caused by a buildup of plaque in the arteries, which can lead to a blood clot that can block the flow of blood to the heart or brain. This can cause a heart attack or stroke, both of which can be fatal.