Chest pain, shortness of breath, and upper body discomfort in the neck, arms, jaw or back are all symptoms of a blood clot in or near the heart, according to the National Heart, Lung and Blood Institute. These signs may also suggest a heart attack or pulmonary embolism.
If not treated, a blood clot in the heart may lead to a heart attack due to the lack of blood flow caused by the clot, explains the National Heart, Lung and Blood Institute. If blood flow to the heart is not restored as quickly as possible, a part of the muscle may become damaged and die. This may not be obvious or severe, but it can cause eventual heart failure and an irregular heartbeat.
Blood clots in this area may also travel to the lungs, which is also quite serious, claims the National Heart, Lung and Blood Institute. In this case, the clot could cause a pulmonary embolism, a condition that can severely damage the lungs and cause low levels of oxygen in the blood. This lack of oxygen can damage other organs if they do not get the oxygen needed to work properly. Pulmonary embolism may also cause death if the clot is too large or there are a number of clots in the area.