ICDs in Certain Heart Attack Patients Reduce Risk of Sudden Cardiac Death

April 3, 2009 - Results from the Medtronic-supported IRIS (Immediate Risk Stratification Improves Survival) clinical trial assessing the use of implantable cardiac devices (ICDs) in certain heart attack patients show a reduction in sudden cardiac death.
Study results, presented this week at ACC, showed that sudden cardiac death in a specific subset of immediate post-MI (myocardial infarction) patients was statistically significantly reduced with ICD therapy. However, in this narrowly defined patient population, ICDs did not reduce mortality from all causes, as all causes are not treatable by ICDs.
The IRIS trial sought to determine if survival amongst a subset of post-MI patients who were at high risk for sudden cardiac death could be improved by ICD therapy received in the first 31 days after a heart attack.
The patients selected for the trial were in the immediate post-MI stage (days five - 30), and based on selective criteria, represent less than five percent of those who have suffered a heart attack. The trial involved 902 patients at 92 centers in seven countries in Europe.
The IRIS results do not conflict with previous data that informed current evidence-based treatment guidelines which showed that use of ICDs in a more broadly defined range of post-MI patients (those who received ICD therapy at least 40 days after experiencing a heart attack) reduced all-cause mortality by 31 percent. Current medical guidelines recommend ICD therapy for post-MI patients with an ejection fraction – a common measure of the heart’s pumping function – of 35 percent and below, and after at least 40 days have passed since their heart attack.
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