Taser Shot to the Chest Can Kill, a Study Warns The electrical shock delivered to the chest by a Taser can lead to cardiac arrest and sudden death, according to a new study, although it is unknown how frequently such deaths occur. Ethan Miller/Getty Images Tasers deliver a current through barbs that are shot into the clothes and skin. The study, which analyzed detailed records from the cases of eight people who went into cardiac arrest after receiving shocks from a Taser X26 fired at a distance, is likely to add to the debate about the safety of the weapons. Seven of the people in the study died; one survived. Advocacy groups like Amnesty International have argued that Tasers, the most widely used of a class of weapons known as electrical control devices, are potentially lethal and that stricter rules should govern their use. But proponents maintain that the devices - which are used by more than 16,700 law enforcement agencies in 107 countries, said Steve Tuttle, a spokesman for Taser - pose less risk to civilians than firearms and are safer for police officers than physically tackling a suspect. The results of studies of the devices" safety in humans have been mixed. Medical experts said on Monday that the new report, published online on Monday in the journal Circulation, makes clear that electrical shocks from Tasers, which shoot barbs into the clothes and skin, can in some cases set off irregular heart rhythms, leading to cardiac arrest. "This is no longer arguable," said Dr. Byron Lee, a cardiologist and director of the electrophysiology laboratory at the University of California, San Francisco. This is a scientific fact. The national debate should now center on whether the risk of sudden death with Tasers is low enough to warrant widespread use by law enforcement. The author of the study, Dr. Douglas P. Zipes, a cardiologist and professor emeritus at Indiana University, has served as a witness for plaintiffs in lawsuits against Taser - a fact that Mr. Tuttle said tainted the findings. "Clearly, Dr. Zipes has a strong financial bias based on his career as an expert witness," Mr. Tuttle said in an e-mail, adding that a 2011 National Institute of Justice report concluded there was no evidence that Tasers posed a significant risk of cardiac arrest "when deployed reasonably." However, Dr. Robert J. Myerburg, a professor of medicine in cardiology at the University of Miami Miller School of Medicine, said that Dr. Zipes's role in litigation also gave him extensive access to data from medical records, police records and autopsy reports. The study, he said, had persuaded him that in at least some of the eight cases, the Taser shock was responsible for the cardiac arrests. "I think when we put together the preponderance of what we know about electrical shocks with his observations, there's enough to say that the phenomenon occurs," he said. But he added, "I suspect the incidence of these fatal events is going to be low and can be minimized by the precautions." Police officers, he said, should take precautions when using the weapons and avoid multiple shocks, prolonged shocks and shocks to the chest. "I'd rather see Tasers out there than bullets flying around," Dr. Myerburg said. But if you have a choice, if the circumstances allow you to avoid either, then physical restraint should be considered.