Thousands of patients are being implanted with high-tech heart devices they probably don’t even need, and might even harm them unnecessarily, according to a new study reported in the New York Times. The devices are called defibrillators, and fire an electric shock to jolt the heart into a normal rhythm in case it starts beating in a disorderly way, which can cause death. About 100,000 are implanted each year in the U.S., in procedures that can cost over $35,000 and involve surgery and anesthesia. Researchers looked at the records of 111,707 people who got implants at 1,227 hospitals in the U.S. from 2006 to 2009, and found that more than 25,000 people (22.5 per cent of all who got them) didn’t match the guidelines of professional societies that specify when they should be used. Most of these patients were 64 to 68, and for unknown reasons, blacks and Hispanics were more likely than whites to get defibrillators they probably didn’t need. At some centres, over 40 per cent of devices were implanted into patients outside the guidelines.