The most frequent cause for a heart attack is obstructed blood flow into the heart muscle, also called myocardial infarction, which leads to a squeezing pain in the chest, often extending to the left arm and sometimes to both arms. Persistent left arm pain requires medical attention, notes Better Medicine.
In some cases, a heart attack presents no chest pain at all, while the discomfort gathers in the shoulder, arm, neck, back and even the jaw -- but not the chest. This is a more common phenomenon for women than it is for men, according to Better Medicine.
Heart attack is not the only reason for pain in the upper left arm. This pain can result from any number of conditions, including tendinitis, osteoarthritis, injury to the joint, fibromyalgia, bursitis, fractured bone, or stress to the shoulder or arm muscle stemming from overuse or lengthy confinement in an awkward position. However, when the arm pain comes suddenly and severely, it is a cause for alarm. To be safe, it is wise to seek medical attention when arm pain is accompanied by chest discomfort, a feeling of dread or anxiety, shortness of breath, pain elsewhere in the upper body, a sense of dizziness, pale skin, clammy skin or fatigue, as stated by Better Medicine.