Stanford study investigates treatment cost effectiveness after heart attack

November 20, 2001

STANFORD, Calif. - Two treatments - the implantable cardioverter defibrillator (ICD) and the drug amiodarone - are both cost-effective ways to protect heart attack survivors against further cardiac complications, including sudden death, according to a new study by researchers at Stanford University Medical Center and the Palo Alto VA Health Care System. ICDs - which received a flurry of attention when Vice President Dick Cheney received one last summer - and amiodarone are now commonly used to prevent sudden cardiac death in patients with irregular heart beats.

The study, led by Gillian Sanders, PhD, assistant professor of medicine in the Center for Primary Care and Outcomes Research at the medical center, will be published today in the Annals of Internal Medicine. It is the first study to analyze the costs and benefits of the two treatments for heart attack patients with no history of arrhythmia, or irregular heart rhythm.

Sanders said more than one million Americans have heart attacks each year, and survivors have a 5 percent to 10 percent risk of dying suddenly within the first year. Most of these sudden deaths are believed to be caused by two types of ventricular arrhythmia: ventricular fibrillation, in which the heart's ventricles don't actually pump and are unable to deliver blood to the rest of the body; and ventricular tachycardia, in which the heart beats too rapidly for the heart to pump effectively.

Sanders said the most common tools used to prevent sudden death are ICDs and amiodarone. ICDs, which are implanted in tens of thousands of Americans each year, apply an electrical shock to restore normal heart rhythm if they detect something is irregular. Amiodarone works by slowing nerve impulses in the heart. Past studies have shown that these treatments are cost-effective ways to improve use of ICDs in the past 10 years, Sanders said.

"Clinical trials have been very supportive of the use of ICDs in a higher-risk population," said Sanders. "As physicians began using the ICD more, it's important that we look at all other populations it could be used in and determine if it's cost-effective."

The researchers began their work by gathering data from the Myocardial Infarction Triage and Intervention patient registry, a Seattle-based registry of heart attack patients. They split up 3,000 patients into three groups according to ejection fraction - a measure of the left ventricle's function that is a powerful predictor of sudden cardiac death - and looked at the cardiac-related mortality rates for each group. They determined, for example, that 8 percent of patients with poor left ventricular function and 1 percent of patients with more normal left ventricular function had a sudden death within the first year, Sanders said.

A computer model next simulated the costs and outcomes that would have resulted from giving the patients ICDs, amiodarone or no special therapy. The costs considered were for implanting an ICD ($25,000), a month's prescription of amiodarone ($190), outpatient doctor visits and future hospitalizations.

After determining how each of the treatment strategies would affect life expectancy, the researchers found that ICDs resulted in the fewest deaths but the highest costs, while amiodarone produced intermediate benefits and costs. The team calculated that in order to cost less than $75,000 for each additional year of life expectancy - a number the team and others often use as a measure of cost-effectiveness - ICDs would need to reduce the number of deaths from ventricular arrhythmias by half and amiodarone would need to reduce the number of deaths by 7 percent.

In reviewing the data, Sanders said ICDs and amiodarone appear cost-effective for those patients at the highest risk of life-threatening arrhythmia. She said clinical trials are being conducted to determine the effectiveness of treatments for heart attack survivors, adding that the research will provide a more definitive answer on overall cost effectiveness.

Sanders expressed optimism about the outcome. "We believe that the needed efficacies set by our study will be confirmed by the ongoing clinical trials," Our numbers are within the range of what people are expecting," she said. "It looks like this is something that the treatments should be able to do. It looks like they will be proven cost effective.We will need to wait for the trial results to be sure, but it looks like in patients at the highest risk after a heart attack, such anti-arrhythmia therapy may be cost effective." stanford.edu
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Sanders collaborated on this study with Mark Hlatky, MD, professor of health research and policy and of medicine; Nathan Every, MD, formerly with the University of Washington in Seattle; Kathryn McDonald, executive director of the Center for Primary Care and Outcomes Research; Paul Heidenreich, MD, assistant professor of medicine at the VA Palo Alto Health Care System; Lori Parson, formerly with the University of Washington in Seattle; and Douglas Owens, MD, associate professor of medicine at the VA Palo Alto Health Care System. The study was part of a larger project led by Hlatky called the Cardiac Arrhythmia and Risk of Death Patient Outcomes Research Team Grant. The project is funded by the Agency for Healthcare Research and Quality and the Health Services Research and Development Service of the Department of Veterans Affairs.

Stanford University Medical Center integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital. For more information, please visit the Web site of the medical center's Office of News and Public Affairs at http://mednews.stanford.edu

MEDIA CONTACT: Michelle Brandt at 650-723-0272 or 723-6911, mbrandt@stanford.edu. BROADCAST MEDIA CONTACT: Sheila Foster at 650-723-3900, safoster@stanford.edu

Stanford University Medical Center

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