Outcomes/Effectiveness Research

Only a small number of heart attack patients may benefit from prophylactic use of implanted automatic defibrillators

A study published in 1996—the Multicenter Automatic Defibrillator Implantation Trial (MADIT)—found that there were 54 percent fewer deaths among heart attack patients who received implantable cardioverter-defibrillators (ICDs) to prevent life-threatening arrhythmias compared with patients who received conventional medical therapy. These findings raised hopes for improving survival of the thousands of heart attack (postinfarct) patients estimated as potentially benefiting from ICDs. However, a more recent study suggests that the actual proportion of these patients at high enough risk to benefit from prophylactic defibrillator placement may range from just 0.3 percent to 1.1 percent.

This finding has substantial health policy implications because the cost of the ICD device and its implantation has been estimated to be $45,000 per device, not including followup costs, says Mark A. Hlatky, M.D., of Stanford University. In a study supported in part by the Agency for Health Care Policy and Research (HS08362), Dr. Hlatky and his colleagues used data from the Cardiac Arrhythmia Suppression Trial (CAST) Registry to calculate the potential benefit of ICDs for postinfarct patients. The CAST Registry includes screening data on 94,797 patients from 35 medical centers, who are at risk for sudden unexpected death. Patients who had suffered a heart attack were screened to identify those at high risk for arrhythmic death using clinical entry criteria, Holter monitor recordings, and ejection fraction.

For details, see "Estimating the proportion of post-myocardial infarction patients who may benefit from prophylactic implantable defibrillator placement from analysis of the CAST registry," by Nathan R. Every, M.D., M.P.H., Dr. Hlatky, Kathryn M. McDonald, M.M., and others, in the American Journal of Cardiology 82, pp. 683-685, 1998.

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