Hospitals in the US are providing faster care to heart attack patients, with more than three quarters of people suffering from major attacks having their blocked arteries opened within 90 minutes of arriving in the emergency room.

The Yale University study of 831 hospitals said that in 2005 only half of cardiac arrest patients were being treated within 90 minutes.

The study, published in the Journal of the American College of Cardiology, found hospitals that had not participated in the campaign to speed up the “door-to-balloon time” process did not improve procedures as quickly.