A silent heart attack is one in which a person does not feel chest pain or any other symptoms (such as a feeling of choking or throat tightness, difficulty breathing, irregular or skipped heartbeat, or numbness or discomfort in the arm or hand).
This type of heart attack is usually not detected unless there are symptoms of another condition, such as heart failure, at the same time. It may not be discovered until later, during a routine physical exam.
A silent heart attack may occur when the nerves in the heart have been damaged by high blood sugar due to diabetes. Because the heart attack does not cause symptoms, it is ignored or not noticed and often causes more damage to the heart. In a person with diabetes, the only signs of a heart attack may be a rising blood sugar level and weakness that does not go away after eating sugar.
WebMD Medical Reference from Healthwise