Survival Rates of Cardiac Arrest Patients Improve With Defibrillation and Aggressive Treatment, Says Mayo Clinic Proceedings Study

Tuesday, May 11, 2004

ROCHESTER, Minn. — The long-term survival rate of patients who suffer cardiac arrest away from a hospital is much better when they are revived with a defibrillator and are entered into an aggressive treatment program while hospitalized, according to a Mayo Clinic Proceedings study.

The study reviewed 200 patients in Olmsted County, Minn., who experienced out-of-hospital cardiac arrest and underwent ventricular fibrillation between November 1990 and December 2000. Researchers examined the in-hospital measures to stabilize the heart, including coronary artery bypass surgery, angioplasty, implantable cardioverter-defibrillators (ICDs), and rhythm stabilization medications, to ascertain how these initial strategies affected long-term survival.

Forty percent of the patients (79) in the study who received rapid defibrillation were discharged from the hospital. The researchers also reported that by the end of the study, more patients were receiving antiarrhythmic therapy, such as an ICD. The researchers found that 66 percent, or 52 patients, were candidates for electrophysiologic testing. Of those patients, 92 percent, or 48 patients, underwent the testing.

T. Jared Bunch, M.D., a Mayo Clinic cardiologist and lead author, said findings in this study are important for three reasons. First, aggressive early defibrillation programs improve survival. Second, the majority of these patients remain at high risk of sudden death and require aggressive evaluation and treatment in hospital to prevent future events. And third, over the decade more patients who survive out-of-hospital cardiac arrest received ICDs as large trials were published that demonstrated the long-term benefit of these devices.

Because of the defibrillation in the field, more patients are surviving. Mayo ClinicÕs data show an increase from 28 percent surviving out-of-hospital cardiac arrest prior to 1990 to the current data of 40 percent. The effects of early defibrillation have increased the number of patients who survive with subsequent demand of immediate hospital resources and targeted therapy for long-term preventive care.

Two treatments that increased during the testing period were electrophysiologic testing and ICDs. The testing involves catheters tipped with electrodes that are threaded through the blood vessels to a variety of spots within the heart, which allows cardiologists to map the spread of electrical impulses through the heart to observe the location of the arrhythmia and the mechanisms that might be causing it. There could be more patients who might benefit from this treatment, the studyÕs authors said.

The study was also conducted by Roger White, M.D., Bernard Gersh, Ph.D., Win-Kuang Shen, M.D., Stephen Hammill, M.D., and Douglas Packer, M.D. of Mayo Clinic.

A peer-review journal, Mayo Clinic Proceedings publishes original articles and reviews dealing with clinical and laboratory medicine, clinical research, basic science research and clinical epidemiology. Mayo Clinic Proceedings is published monthly by Mayo Foundation for Education and Research as part of its commitment to the medical education of physicians. The journal has been published for more than 75 years and has a circulation of 130,000 nationally and internationally. A copy of the article will be available on-line after the embargo lifts at www.mayo.edu/proceedings.

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Contact:
John Murphy
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e-mail: newsbureau@mayo.edu

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