Background: To date, the implantable cardioverter-defibrillator (ICD) has been shown to be effective for primary prevention of sudden cardiac death only in selected groups of patients in the chronic phase after myocardial infarction.
Methods and results: The Immediate Risk-Stratification Improves Survival (IRIS) Study compares ICD therapy with no ICD therapy in selected high risk patients early after myocardial infarction. Special emphasis is placed on optimal acute and long term medical therapy in all patients including metoprolol CR/ZOK. The hypothesis is tested that use of the ICD reduces overall mortality. For that purpose, consecutive acute ST elevation or non-ST elevation myocardial infarction patients are collected in a registry. From this denominator, patients are screened, and enrolled early after myocardial infarction (day 5 to day 31) if they exhibit both a reduced left ventricular ejection fraction < or =40% and a heart rate > or =100 bpm on the first available electrocardiogram (criterion I), or non-sustained ventricular tachycardia at a rate > or =150 bpm during Holter (criterion II).
Conclusions: IRIS is a large scale prospective, randomized trial to evaluate the benefit of ICD therapy for reduction of total mortality in patients considered at high risk of sudden death early after acute myocardial infarction.