The threat of imminent death awaits the 250,000 persons who suffer a cardiac arrest outside the hospital each year, especially those for whom defibrillation fails to shock the heart back to normal beating.
A clinical trial performed by University of Washington researchers, reported in the Sept. 16 issue of the New England Journal of Medicine, shows that an intravenous anti-arrhythmia medication, amiodarone, can save the lives of many patients who do not respond to defibrillation.
Dr. Peter Kudenchuk, associate professor of medicine and director of arrhythmia services at University of Washington Medical Center in Seattle, and colleagues performed the study, called ARREST (Amiodarone in the Out-of-Hospital Resuscitation of Refractory Sustained Ventricular Tacharrhythmias). The study was performed in conjunction with Medic One, Seattle/King County's highly regarded emergency response service based at Harborview Medical Center.
They found that resuscitation to a stable heart rhythm was improved by nearly 30 percent in people treated with intravenous amiodarone by emergency medical personnel at the scene of their collapse, compared to those who received other standard treatments for cardiac arrest.
This benefit was seen even when amiodarone was given late in the course of resuscitation, and was especially evident in women compared to men.
Kudenchuk noted that the clinical trial is the first of its kind to compare the effectiveness of an anti-arrhythmia medication with all standard treatments in victims of out-of-hospital cardiac arrest.
The drug was administered to 504 people in Seattle and surrounding King County, Wash., who suffered cardiac arrest due to a dangerous heart rhythm (ventricular fibrillation) and were treated at the scene by Medic One. Patients ranged in age from 20 to 94 years. The majority were men and the majority went into cardiac arrest at home.
"For every 10 persons treated with amiodarone for shock-resistant cardiac arrest, one additional person was resuscitated and admitted alive to the hospital," said Kudenchuk.
He noted that the main treatment endpoint for the ARREST trial was being successfully resuscitated and admitted to the hospital. The trial was not designed to evaluate the effect of amiodarone treatment on outcome after hospitalization. Although a small improvement in survival to hospital discharge with full recovery of brain function was observed in persons treated with amiodarone, the investigators did not feel that this difference was conclusive.
"Stopping the cardiac arrest and successfully getting patients to the hospital is a big step, but it's only the first hurdle," said Kudenchuk. "The next step is to determine whether drugs like amiodarone can improve long-term survival after cardiac arrest. "
Amiodarone is marketed as Cordarone IV by Wyeth-Ayerst Laboratories. The Medic One Foundation provided approximately two-thirds of the funding for the study and Wyeth-Ayerst, approximately one-third.
Materials provided by University Of Washington. Note: Content may be edited for style and length.
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