Cardiac arrest, which often leads to a heart attack, is frighteningly common: every minute of every day there is another victim, according to the American Red Cross. Almost 80% of cardiac arrests occur at home and are witnessed by a family member. Would you know what to do if someone you loved experienced a cardiac emergency? Make sure you're prepared -- take a CPR (cardiopulmonary resuscitation) class and get trained to use an automated external defibrillator, or AED. It could mean the difference between life and death.