Rapid Defibrillation in Cardiac Arrest Leads to Near-Normal Life Span, Quality of Life

Wednesday, June 25, 2003

ROCHESTER, Minn. — Mayo Clinic researchers have found that cardiac-arrest patients who are revived using automated external defibrillators (AEDs) and survive to hospital discharge live as long as patients with similar underlying cardiac disease. They also have a nearly normal quality of life compared with the general population, according to the findings published in the June 26 issue of the New England Journal of Medicine.

"Nationally, of patients who experience cardiac arrest due to ventricular fibrillation outside of a hospital, only 15 percent or fewer survive," says Roger White, M.D., the Mayo Clinic anesthesiologist who led an Olmsted County, Minn., initiative to place AEDs in police cars to improve early response times. "We have known for some time that our program produces dramatically better short-term results, with 40 percent living to be discharged from the hospital. Until now, we had no long-term data on what kind of life these patients have had after surviving cardiac arrest, only anecdotes and small studies. This study shows rapid defibrillation not only saves lives, but that most survivors are able to resume normal activities."

The study included every Olmsted County patient who had an out-of-hospital cardiac arrest between November 1990 and January 2001, and who received early defibrillation for ventricular fibrillation. Ventricular fibrillation is a rapid quivering of the heart's main pumping chambers that prevents them from delivering blood to the rest of the body. AEDs treat this condition by shocking the heart back into a normal rhythm through pads placed on the chest.

Of the 200 ventricular fibrillation patients, 145 (72 percent) survived to hospital admission and 79 (40 percent) eventually left the hospital with good overall neurological capability (74 patients) or only very moderate overall disability (5 patients). The survivors were followed for an average of 4.8 years, during which time 19 died. While their five-year survival rate (79 percent) was lower than that of general U.S. residents of the same age and sex (86 percent), it was identical to that of a matched group of patients with the same underlying diseases, but who had not suffered a cardiac arrest. In fact, most of the 19 deaths among study participants were from other causes; the five-year survival, free of cardiac-caused death, was 92 percent.

At their most recent follow-up visit, patients completed a standardized survey, which measures perceptions of general health status, quality of life, sense of well-being and ability to function. With the exception of slightly decreased vitality, the survivors' scores were within the normal range for the general U.S. population of the same age and sex.

Dr. White attributes the long-term positive results both to the rapid defibrillation program and to treatment of the underlying disease that had caused the cardiac arrest. "The time from 911 call to first shock averaged 5.7 minutes among the 79 initial survivors, but it was 6.6 minutes for the 63 who died in the hospital," explains Dr. White. "Clearly, saving just a few seconds in administering the shock can make a tremendous difference in saving lives."

"Earlier shock administration also helped prevent damage that might have reduced the effectiveness of heart disease treatment," he continues. "Many of the survivors had bypass surgery, and the majority had internal defibrillators implanted or drug therapy to prevent or quickly end another heart-rhythm disturbance. These patients were in better shape and gained more from these therapies because their cardiac arrests had been of shorter duration."

"In these patients, rapid defibrillation has turned a typically lethal event into virtually a nonevent, at least from the long-term health perspective," says co-investigator Douglas Packer, M.D., a Mayo Clinic cardiologist. "For those we are able to save, it becomes almost as if it never happened."

"Too often, cardiac arrest is a patient's first and last sign of a heart problem," Dr. White concludes. "EDs can give many who would otherwise have died another chance at a full and productive life."

Other authors of the paper, "Long-Term Outcomes of Out-of-Hospital Cardiac Arrest after Successful Early Defibrillation,"include T. Jared Bunch, M.D.; Bernard Gersh, M.B., Ch.B.; Ryan Meverden; David Hodge; Karla Ballman, Ph.D.; Stephen Hammill, M.D.; and Win-Kuang Shen, M.D.

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Tuesday, June 24, 2003
Rapid Defibrillation Survival

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