Comparison of efficacy of the implantable defibrillator in Europe and in the United States

ESC Congress 2003

Sudden cardiac death from ventricular tachyarrhythmias is the leading cause of death in Europe and the US. It effects hundreds of thousands people each year. Many of them have known heart disease, mainly coronary artery disease. The implantable defibrillator (ICD) effectively treats such arrhythmias and prevents sudden cardiac death. Identification of patients at risk who may gain profit from prophylactic ICD implantation remains a difficult task for the cardiologist.

The Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) enrolled patients with a history of myocardial infarction and severely depressed left ventricular function without a history of life-threatening arrhythmias. The study was supported by an unrestricted research grant from GUIDANT, St.Paul, Minn. Patients were randomized to receive best medical therapy only or ICD implantation on top of best therapy. Over the course of four years 1232 patients were enrolled from 71 centers in the US and 5 centers in Europe. After a mean follow-up of 20 months, ICD therapy was associated with a 31 percent reduction in the risk of death.

In order to assess potential differences in clinical characteristics and outcome between European and US patients enrolled in the MADIT II trial ICD efficacy in the European patients was compared with US patients. European centers enrolled 109 (9%) of the total 1232 patients. European patients were younger, had a higher prevalence of symptomatic heart failure, but had a higher left ventricular ejection fraction than US patients. The percentage of female patients enrolled in MADIT II was lower in Europe than in the US (8% vs. 16%). Patients in Europe received more single chamber ICDs than US patients (86% vs. 53%). Also medications for the treatment of heart failure were slightly different in European and US patients.

During the course of the study, appropriate ICD therapy was similar in both groups. There was no difference in the incidence of arrhythmic death, heart failure death and overall mortality between European and US patients.

Although some differences in patient characteristics exist between patients enrolled in MADIT II in Europe and the United States with different rates of implantation of single vs. dual chamber ICD units, ICD efficacy seems to be similar in the two geographic regions.

Dr. Sven Reek
Univ. Hospitals Magdeburg, Div. of Cardiology
Germany

Important: This press release accompanies a poster or oral session given at the ESC Congress 2003. Written by the investigator himself/herself, this press release does not necessarily reflect the opinion of the European Society of Cardiology