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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Cardiac-resynchronization therapy for the prevention of heart-failure events
Arthur J Moss1, W Jackson Hall, David S Cannom
1Department of Medicine, University of Rochester Medical Center, Rochester, NY 14642, USA. heartajm@heart.rochester.edu
Insights
Cardiac-resynchronization therapy (CRT) with an implantable cardioverter-defibrillator (ICD) significantly reduced heart failure events in patients with mild symptoms and reduced ejection fraction. This combination therapy did not impact overall mortality but improved cardiac function.
Area of Science:
- Cardiology
- Electrophysiology
- Heart Failure Management
Background:
- Mildly symptomatic patients with reduced ejection fraction and wide QRS complex are candidates for advanced heart failure therapies.
- The efficacy of cardiac-resynchronization therapy (CRT) in this population requires further investigation.
Purpose of the Study:
- To evaluate the effectiveness of CRT combined with an implantable cardioverter-defibrillator (ICD) in reducing death or heart failure events.
- To assess the impact of CRT on cardiac function in patients with mild heart failure symptoms.
Main Methods:
- A randomized trial involving 1820 patients with cardiomyopathy, ejection fraction ≤30%, and QRS duration ≥130 msec.
- Patients were assigned to CRT plus ICD or ICD alone in a 3:2 ratio.
- The primary endpoint was the first occurrence of death from any cause or a nonfatal heart failure event.
Main Results:
- The CRT-ICD group showed a 34% relative risk reduction in the primary endpoint compared to the ICD-only group (17.2% vs. 25.3%, P=0.001).
- CRT significantly reduced heart failure events, particularly in patients with QRS duration ≥150 msec.
- Left ventricular volumes decreased, and ejection fraction improved with CRT; no significant difference in overall mortality was observed.
Conclusions:
- CRT combined with ICD is effective in decreasing heart failure events for relatively asymptomatic patients with low ejection fraction and wide QRS complex.
- CRT improves cardiac function, offering a significant benefit in heart failure management for selected patients.
Background:
This trial was designed to determine whether cardiac-resynchronization therapy (CRT) with biventricular pacing would reduce the risk of death or heart-failure events in patients with mild cardiac symptoms, a reduced ejection fraction, and a wide QRS complex.
Methods:
During a 4.5-year period, we enrolled and followed 1820 patients with ischemic or nonischemic cardiomyopathy, an ejection fraction of 30% or less, a QRS duration of 130 msec or more, and New York Heart Association class I or II symptoms. Patients were randomly assigned in a 3:2 ratio to receive CRT plus an implantable cardioverter-defibrillator (ICD) (1089 patients) or an ICD alone (731 patients). The primary end point was death from any cause or a nonfatal heart-failure event (whichever came first). Heart-failure events were diagnosed by physicians who were aware of the treatment assignments, but they were adjudicated by a committee that was unaware of assignments.
Results:
During an average follow-up of 2.4 years, the primary end point occurred in 187 of 1089 patients in the CRT-ICD group (17.2%) and 185 of 731 patients in the ICD-only group (25.3%) (hazard ratio in the CRT-ICD group, 0.66; 95% confidence interval [CI], 0.52 to 0.84; P=0.001). The benefit did not differ significantly between patients with ischemic cardiomyopathy and those with nonischemic cardiomyopathy. The superiority of CRT was driven by a 41% reduction in the risk of heart-failure events, a finding that was evident primarily in a prespecified subgroup of patients with a QRS duration of 150 msec or more. CRT was associated with a significant reduction in left ventricular volumes and improvement in the ejection fraction. There was no significant difference between the two groups in the overall risk of death, with a 3% annual mortality rate in each treatment group. Serious adverse events were infrequent in the two groups.
Conclusions:
CRT combined with ICD decreased the risk of heart-failure events in relatively asymptomatic patients with a low ejection fraction and wide QRS complex. (ClinicalTrials.gov number, NCT00180271.)
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