Heart attacks strike about 1.2 million people every year in America alone, many of them fatally. Of those, most are caused by coronary artery disease--the biggest killer of both men and women in the U.S.--and something like 70 percent of those strike without warning. Coronary artery disease is sneaky like that. Symptoms generally don’t outwardly manifest themselves until someone is on the floor, short of breath, wondering what just kicked them in the chest. Doctors battling these cardiac blockages generally enter the fight at a severe disadvantage.