Tuesday, April 1, 2008

Late-breaking clinical trial at ACC: Home Automated External Defibrillator Trial results
By Kelly Winget

Sudden cardiac arrests occur every few minutes in the United States, and it can be difficult for emergency medical service personnel to reach people at their homes in time. DCRI researchers worked on the first study to review the potential life-saving benefits of using automated external defibrillators (AEDs) at home for people at moderate risk for cardiac arrest.

Results from the Home Automated External Defibrillator Trial (HAT) were presented today, April 1, in a late-breaking clinical trial session at the American College of Cardiology 2008 Scientific Sessions. Results were also simultaneously published online in the New England Journal of Medicine.

One of the most common causes of sudden cardiac arrest is ventricular fibrillation, when the heart rhythm becomes irregular and blood flow to the heart and the rest of the body is disrupted. An electrical shock, such as one from an AED, can help return the heart to its normal rhythm if it is delivered within a few minutes from the start of cardiac arrest.

Researchers wanted to determine if AED use at home would improve survival rates among people who are not in a high-risk population for having sudden cardiac arrest.

Approximately 7,000 patients in seven countries were enrolled in the study. The patients had all had heart attacks in the past, and each had someone at home who was willing and able to perform CPR or to use an AED. Patients were randomized and their home care support providers were instructed to either call emergency medical services (EMS) and begin performing CPR, or to use an AED before calling EMS and performing CPR. The family members or home companions of the patients watched training videos about proper techniques for CPR and use of AEDs.

Patients in the study were followed for approximately three years and researchers found that survival rates were almost identical between the two groups, with 6.5 percent of patients in the CPR control group who died from sudden cardiac arrest, and 6.4 percent of patients in the AED group.

Researchers noted that there were significantly fewer incidences of sudden cardiac arrest occurring at home than anticipated, and only half of the cardiac arrests were witnessed by the family member or companion. However, patients whose hearts were shocked by the AEDs had long-term survival rates around 28 percent, which indicates that the AEDs were safe and effective when used. Typical survival rates for people who have sudden cardiac arrest at home vary between 2 and 6 percent.

The researchers note that for patients who have had heart attacks, it is not common to train a patient's spouse or family members on when to call emergency medical services or how to perform CPR in case of sudden cardiac arrest. Researchers hope the study results will encourage medical personnel to provide this instruction to a patient's family after a heart attack.

The study was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health. AEDs were provided to patients free of charge by Philips Medical Systems and Laerdal Medical.

DCRI researchers who worked on the study include Kerry Lee, Ph.D., Daniel Mark, MD, Linda Davidson-Ray and Nancy Clapp-Channing. Steven McNulty was the principal statistician, and Meredith Smith headed up the CEC effort for the DCRI.