Other Studies
A number of studies have previously demonstrated that cardiac resynchronization therapy can decrease symptoms and improve exercise capacity, quality of life, and ventricular function. In some, but not all, studies CRT was combined with defibrillation (CRT-D), making it difficult to isolate the effect of CRT alone in relation to the risk of complications and death. For comparison, the following studies are summarized:
- MIRACLE
- MIRACLE ICD
- DEFINITE
- COMPANION
MIRACLE - Multicenter InSync Randomized Clinical Evaluation
Abraham WT. N Engl J Med. 2002;346:1845-1853.
Objective:
- Evaluate the clinical effects of CRT in patients with moderate to severe heart failure
Inclusion criteria:
- NYHA Class III or IV
- EF < 35%
- QRS interval > 130
Results:
CRT resulted in
- Significant improvement in physical capabilities and functional class
- Improvement in ejection fraction
- Fewer hospitalizations
- Fewer IV medications
MIRACLE ICD - Multicenter InSync Randomized Clinical Evaluation ICD Study
Young JB, JAMA. 2003;289:2685-2694.
Objective:
- Evaluate the safety and efficacy of combined CRT and ICD therapies in patients with moderate to severe heart failure
Inclusion criteria:
- NYHA Class III or IV
- LVEF < 35%
- QRS > 130
Results:
- CRT resulted in significant improvements in quality of life and functional class
- CRT was not associated with pro-arrhythmia
- The addition of CRT did not impair function of ICD to terminate arrhythmias
DEFINITE - Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation
Kadish A. N Engl J Med. 2004;350:2151-2158.
*DEFINITE Study conducted by St. Jude Medical using St. Jude Medical devices
Objective:
- Evaluate the effectiveness of ICD therapy compared to optimal medical therapy in non-ischemic cardiomyopathy patients
Inclusion criteria:
- NYHA Class I, II, III
- Non-ischemic cardiomyopathy
- LVEF < 35%
- NSVT
Results:
- In patients with non-ischemic dilated cardiomyopathy treated with optimal medical therapy and CRT, the risk of death was reduced by 80%
COMPANION - Comparison of Medical Therapy, Pacing and Defibrillation
in Heart Failure Trial*
Bristow M. N Engl J Med . 2004;350:2140-2150
*COMPANION study was conducted by Guidant using Guidant Corporation devices
Objective:
- Evaluate the effectiveness of CRT with or without ICD in reducing the risk of death and hospitalizations in patients with advanced heart failure and intraventricular conduction delays.
Inclusion criteria:
- NYHA Class III or IV (ischemic or
non-ischemic)
- LVEF < 35%
- LVEDD < 60 mm
- QRS < 120 ms,
- PR interval > 150 ms
- History of HF hospitalization < 12 months, > 1 month prior to enrollment
Results:
In patients with advanced heart failure and prolonged QRS
- CRT and CRT-D reduce all-cause death and all cause hospitalizations by 19-20%
- CRT reduces all-cause mortality by 24%
- CRT-D reduces all-cause mortality by 36%
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