Blood Clots

Blood clots or thrombi kill an American about every 5 minutes. Wikipedia says this about blood clots.

A thrombus, or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system (i.e. clotting factors). A thrombus is normal in cases of injury, but pathologic in instances of thrombosis.
Mural thrombi are thrombi adherent to the vessel wall. They are not occlusive and affect large vessels, such as heart and aorta. Grossly they appear grey-red with alternating light and dark lines (lines of Zahn) which represent bands of fibrin (lighter) with entrapped white blood cells and red blood cells (darker).

Scientists are actively studying blood clots, and here are links to some of their research.

In a large, long-term study, researchers followed 30,239 adults who were 45 years or older for 4.6 years. Researchers rated participants' heart health using the seven health indicators from the American Heart Association Life's Simple 7. They include being physically active, avoiding smoking, following a healthy diet, maintaining a healthy body mass index, and controlling blood sugar levels, blood pressure and cholesterol. They then compared the incidence of blood clots among those whose heart health rated as inadequate, average and optimum.