If pain in left breast under is this heart attack?

Unlikely given: Your age but only further evaluation could reveal such.

Possible: Pain from the jaw to upper abdomen could be related to heart. Not all pain is heart attack though. Chest pain should be evaluated by a physician.

Possible: Left sided pressure chest pain that increase with activities and improved with rest. Associated with left arm irradiation, sweating and rapid heart rate. Risk factors for heart attack are obesity/sedentary lifestyle, hypertension, diabetes, high cholesterol, smoking, psychosocial stressors, abdominal obesity. Old age, diabetes, and females have an increase risk atypical chest pain presentation.

It varies: Symptoms of heart attack are classically crushing chest pain that radiates into the jaw and left arm. Other symptoms can include pain under a breast. If you have any question whether you may be having a heart attack, you should immediately go to your nearest emergency department.