A simple test appears very good at ruling out heart attacks in people who go to emergency rooms with chest pain.
It's a big public health issue and a huge worry for patients.
A large study in Sweden found the blood test plus an electrocardiogram were 99 percent accurate at showing which patients could safely be sent home rather than admitted for more tests.
Chest pain sends about 15 million people to emergency rooms in the United States and Europe each year.
It usually is from anxiety, indigestion or less-serious things than a heart attack.
Knowing who can safely go home saves money and avoids harm from unnecessary tests and hospital-acquired infections.
The study was discussed Sunday at an American College of Cardiology conference in Washington.