Lectures curated around PBS's Take One Step Health Campaign special The Hidden Epidemic: Heart Disease in America, which examines the number one killer of Americans.

How can a seemingly healthy 44-year-old suddenly drop dead from a massive heart attack? His case is not unusual, as the 90-minute documentary explains. More than half of all people who die of heart disease succumb suddenly without warning—and the other half have the disease lurking in their bodies for many years before it strikes. There is no cure, but doctors are making remarkable discoveries about the disease: where it starts, how it occurs, and what that means for us.