Immediate Risk-Stratification Improves Survival - IRIS

Description:

The goal of the trial was to evaluate implantable cardioverter-defibrillator (ICD) therapy in patients with low ejection fraction or other high-risk criteria early after acute myocardial infarction (MI).

Hypothesis:

ICD implantation early after acute MI will improve survival in patients at high risk for sudden cardiac death.

Study Design

  • Randomized
  • Parallel

Patients Screened: 62,944
Patients Enrolled: 898
Mean Follow Up: 37 months
Mean Patient Age: 63 years
Female: 22%
Mean Ejection Fraction: 35%

Patient Populations:

  • Acute MI within the last 5-31 days
  • Either left ventricular ejection fraction ≤40% and heart rate ≥90 bpm (criterion I) and/or nonsustained ventricular tachycardia ≥150 bpm on Holter monitor (criterion II)

Primary Endpoints:

  • All-cause mortality

Secondary Endpoints:

  • Sudden cardiac death
  • Nonsudden cardiac death
  • Noncardiac death

Drug/Procedures Used:

Patients with high-risk criteria early after acute MI were randomized to ICD implantation (445) or no ICD implantation (453).

Concomitant Medications:

For the entire study population: beta-blockers 89%, antiplatelet agents 99%, angiotensin-converting enzyme inhibitors 82%, and statins 91%

Principal Findings:

Index diagnosis was ST-elevation MI in 77% of patients. Multivessel coronary disease was present in 57% of patients. Approximately two-thirds of patients received PTCA, and approximately 25% of patients received no reperfusion therapy. There was no difference in the primary endpoint of all-cause mortality between groups at 3 years (26.1% vs. 25.8%, p = 0.76).

Subgroup analysis failed to identify a subgroup of patients who benefited from early ICD implantation. While the incidence of sudden cardiac death was significantly reduced in the ICD group, the incidence of nonsudden cardiac death was increased.

Interpretation:

The benefit of ICD implantation in patients with prior MI and left ventricular dysfunction was established in the MADIT II trial. However, the DINAMIT trial failed to demonstrate a benefit to routine early ICD implantation following MI.

The results from IRIS complement the findings from DINAMIT, and suggest that the reduction in sudden cardiac death with ICD implantation early after MI is counterbalanced by an increase in nonsudden cardiac death. Based on these findings, routine ICD implantation early after MI cannot be recommended at this time.

References:

Steinbeck G, Andresen D, Seidel K, et al. Defibrillator implantation early after myocardial infarction. N Engl J Med 2009;361:1427-36.

A Randomised Study of the Effects of Optimal Medical Therapy Alone or in Combination With Cardioverter-Defibrillator Implantation on Survival in Patients Early After Myocardial Infarction. Presented by Dr. Gerhard Steinbeck at ACC.09/i2, Orlando, FL, March 2009.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, SCD/Ventricular Arrhythmias, Acute Heart Failure

Keywords: Myocardial Infarction, Tachycardia, Ventricular, Ventricular Fibrillation, Heart Failure, Stroke Volume, Heart Rate, Death, Sudden, Cardiac, Defibrillators, Implantable


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