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Check out new and important updates in Arrhythmia:
 The Effect of Cardiac Resynchronization Therapy (CRT) in Heart Failure
Update on Atrial Fibrillation Ablation: Cryo Energy
Protection Against Sudden Cardiac Death With the Implantable Defibrillator
The Effect of Cardiac Resynchronization Therapy (CRT) in Heart Failure
Aysha Arshad, MD
Division of Cardiology
St. Luke's-Roosevelt Hospital Center
Heart Failure
Despite recent advances in medical therapy, heart failure continues to cause illness and death. This occurs most commonly because the main pumping chamber of the heart (left ventricle) is not contacting effectively. In advanced heart failure, certain diseased areas of the heart may have significant delay in contraction relative to other healthier areas and this is referred to as dyssynchrony. The aim of cardiac resynchronization therapy, or CRT, is to stimulate all areas of the heart to contract simultaneously and thereby improve cardiac function and eliminate dyssynchrony.
CRT Devices
Most pacemakers and defibrillators have a lead which is placed in the right ventricle. Cardiac resynchronization therapy devices have an extra lead which is placed in a vein (coronary sinus) overlying the left ventricle and this lead or pacing electrode can be used to cause simultaneous contraction in all areas of the ventricle. These leads are used together to stimulate ('pace') both ventricles. In addition most CRT devices have an extra lead in the right atrium so atrial and ventricular contraction can be co-coordinated for added benefit.
Benefits of CRT
In appropriately selected patients cardiac resynchronization therapy has been proven to improve symptoms of heart failure and quality of life and to reduce the chance of being admitted to hospital with worsening heart failure. No meaningful improvement in survival could be established from the initial patient trials studying the effects of cardiac resynchronization therapy.
CARE-HF
Cardiac ResynchronizationóHeart Failure (CARE-HF) was the first trial to evaluate the long-term effects of cardiac resynchronization therapy alone on mortality and morbidity among moderate to severe heart failure patients. This was a multicenter, international, randomized trial comparing the effect on the risk of complications and death of standard medical therapy alone with that of the combination of medical therapy and CRT (without a defibrillator) in patients with cardiac dysfunction, dyssynchrony, and symptomatic heart failure.
Patients were enrolled at 82 European centers; enrollment began in January 2001 and ended in March 2003. 813 patients were enrolled: 404 received medical therapy (control group) and 409 received cardiac resynchronization therapy and optimal medical therapy (therapy group). Patients were evaluated periodically and the two groups were compared with regard to death, hospitalization and quality of life.
By the end of the study, the primary end point had been reached in 159 patients in the cardiac resynchronization therapy group, as compared with 224 patients who received medical therapy alone (Figure 1). There were 222 unplanned hospitalizations for a major cardiovascular event in the CRT group and 384 in the control group.
Figure 1
As compared with medical therapy alone, cardiac resynchronization therapy significantly reduced the risk of the composite end point of death from any cause or hospitalization for worsening heart failure. As compared with patients in the medical-therapy group, patients in the cardiac-resynchronization group had less severe symptoms and a better quality of life at 90 days.
At both 3 months and 18 months, the left ventricular ejection fraction (pumping action) was significantly greater, the left ventricular chamber size was significantly smaller, the area of mitral regurgitation (leaky mitral valve) was significantly smaller, and the mechanical delay was significantly shorter in the cardiac resynchronization therapy group than in the medical therapy group. All of these are very favorable effects on overall cardiac performance.
CARE-HF investigators concluded that in patients with heart failure and cardiac dyssynchrony, cardiac resynchronization therapy improves symptoms and the quality of life and reduces complications and the risk of death from heart failure. These benefits are in addition to those afforded by standard medical therapy. The implantation of a cardiac resynchronization therapy device should routinely be considered in such patients.
This was the first trial to convincingly show a mortality reduction from cardiac resynchronization therapy as well as decrease in hospitalizations from heart failure.
If you are suffering from cardiomyopathy and heart failure, please consult your physician about cardiac resynchronization therapy for further management of your condition. Dr. Aysha Arshad at St. Lukes-Roosevelt Hospital Center in New York City is available for consult on these cases, and can be reached at (212) 523-4017.
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