Pain in the left arm or shoulder
The most common irradiation of chest pain is to the left arm or shoulder. This sign is commonly recognized as one of the most important in myocardial infarction or heart attack, and it is caused by a connection of the sensory nerves of the heart and those found in the left portion of the upper limb. These nerves go through the same path to reach the brain, and intense pain is interpreted by the brain as if it was coming from all of this area. This is called referred pain, and it is one of the most common reasons why some people have an undiagnosed heart attack.