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Defibrillator in Acute Myocardial Infarction Trial - DINAMIT
Description:
The goal of the trial was to evaluate the effects of prophylactic implantable cardioverter defibrillator (ICD) therapy in high-risk patients early after acute myocardial infarction (AMI).
Hypothesis:
Mortality in survivors of AMI will be lower in those treated with ICD therapy than patients not treated with ICD therapy.
Study Design
Study Design:
Patients Enrolled: 674
Mean Follow Up: Mean follow-up 2.5 years
Mean Patient Age: Mean age 62 years
Female: 24
Mean Ejection Fraction: Mean baseline EF 28%
Patient Populations:
Age 18-80 years, recent MI (6-40 days), left ventricular ejection fraction (EF) ≤35%, and evidence of impaired cardiac autonomic modulation (i.e., depressed heart rate variability or increased mean 24-hour heart rate)
Exclusions:
CHF with New York Heart Association class IV, coronary artery bypass grafting, or three-vessel PTCA for index MI
Primary Endpoints:
All-cause mortality
Secondary Endpoints:
Arrhythmic death and quality of life
Drug/Procedures Used:
Patients were randomized to ICD therapy (n=332) versus no ICD therapy (n=342) in addition to best medical treatment in survivors of AMI. Cause of death was adjudicated by a committee blinded to treatment assignment.
Principal Findings:
Randomization occurred an average of 18 days after the MI, and the ICD was implanted an average of 6.3 days after randomization. Medical therapy included beta-blockers (87%), angiotensin-converting enzyme inhibitors (95%), antiplatelet agents (92%), and lipid-lowering agents (78%).
Anterior MI was present in 72% of patients, and 48% of patients had chronic heart failure (CHF) associated with the index MI. Acute reperfusion therapy (percutaneous transluminal coronary angioplasty, thrombolytic, or both) was performed in 62% of patients.
The primary endpoint of all-cause mortality did not differ between treatment arms (7.5% per year in the ICD arm vs. 6.9% per year in the control arm, hazard ratio [HR] 1.08, 95% confidence interval [CI] 0.76-1.55, p=0.66). Death due to arrhythmia was lower in the ICD arm (1.5% per year vs. 3.5% per year, HR 0.42, 95% CI 0.22-0.83, p=0.009) while nonarrhythmia deaths were higher in the ICD arm (6.1% per year vs. 3.5% per year, HR 1.75, 95% CI 1.11-2.76, p=0.016).
Interpretation:
Among recent post-MI patients, prophylactic implantable defibrillator therapy was not associated with a reduction in the primary endpoint of all-cause mortality compared with optimal medical therapy. As would be expected, the frequency of arrhythmia deaths was lower in the prophylactic ICD therapy arm. However, nonarrhythmia deaths were higher in the ICD arm.
The authors suggested that in patients with recent MI, ICD therapy changes the mode of death from arrhythmia to nonarrhythmia (a survival effect from arrhythmia death). In prior trials, prophylactic ICD therapy has been associated with improved survival in patients with ischemic cardiomyopathy, but prophylactic use had not previously been evaluated in recent post-MI patients.
References:
Hohnloser SH, et al. Prophylactic Use of an Implantable Cardioverter–Defibrillator after Acute Myocardial Infarction. N Engl J Med 2004;351:2481-8.
Presented by Drs. Stewart Connelly and Stefan H. Hohnloser at the American College of Cardiology Annual Scientific Session, March 2004.
Keywords: Myocardial Infarction, Follow-Up Studies, Platelet Aggregation Inhibitors, Ventricular Fibrillation, Lipids, Heart Rate, Angioplasty, Balloon, Coronary, Goals, Tachycardia, Ventricular, Cardiomyopathies, Heart Failure, Stroke Volume, Bradycardia, Confidence Intervals, Coronary Artery Bypass, Death, Sudden, Cardiac, Defibrillators, Implantable
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