An individual can live approximately 3 to 6 minutes after the heart stops, according to HowStuffWorks and About.com. If the heart stops and the individual has not been resuscitated after about 6 minutes, the brain starts to die because of the lack of oxygen.
Since the heart supplies oxygen to the brain that is necessary for survival, getting oxygen to the brain is the most important goal if the heart stops. Cardiopulmonary resuscitation is vital for getting oxygen to the brain. The sooner that CPR is started after the heart stops, the lower the chance for irreparable brain damage, according to HowStuffWorks.