The chest/Cardiac pain can be encountered at any time, any place to any person & shall lead to Cardiac Arrest/Death. With experience  of  chest  discomfort/pain first step to manage the patient/yourself is Sit down on ground/chair etc  Can  lean  forward at 75  degrees  of angle, stop all activities & Start deep forceful respiration (inspiration/expiration, expiration can be preferred though open mouth), so that pressure  gradient should continously  change over to make blood flow turbulent  to make/keep  the heart beating, even on oxygen mask and Never lie down on bed  at home, in ambulances, in hospital even for ECG. Till the pain subsides/relieved even with medication.

A sitting posture is a Natural Gift to save lives in the chest pain/cardiac pain. Do share your experiences/ideas!