Reducing Mortality With Device Therapy in Heart Failure
Reducing Mortality With Device Therapy in Heart Failure
Use of device therapy to prevent sudden cardiac death in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Three multicenter prospective clinical trials-Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)-were conducted to determine the effectiveness of devices in reducing mortality in patients with heart failure who did not have a history of ventricular arrhythmias. The 3 trials varied in the devices used, the population of patients included, and the study designs. In SCD-HeFT, implantable cardioverter defibrillators were more effective than pharmacological therapy in preventing mortality among patients with mild to moderate heart failure. In COMPANION, cardiac resynchronization therapy alone and cardiac resynchronization therapy plus an implantable cardioverter defibrillator were more effective than optimal drug treatment in reducing morbidity and all-cause mortality in patients with moderate to severe heart failure. In CARE-HF, cardiac resynchronization therapy alone was more effective than optimal drug treatment in reducing all-cause mortality in patients with moderate to severe heart failure. No direct comparison of the devices used has been done. These 3 clinical trials provide clear evidence that device therapy is beneficial for some patients with heart failure, even patients who do not have a history of ventricular arrhythmia.
As mortality from myocardial infarction has decreased because of improved treatment, the number of persons living with heart failure has increased. Heart failure is the only major cardiovascular disorder that is increasing in incidence and prevalence; roughly 5 million people in the United States have this disorder. Heart failure is a major cause of sudden cardiac death (SCD). More than half of the deaths due to heart failure are from SCD; the remainder are due to progressive heart failure. The most important preexisting condition and the best predictor of SCD is left ventricular dysfunction, the underlying cause of heart failure. Ventricular tachycardia reentry circuits occur when the left ventricle is enlarged because of ischemia, scarring, or muscle stretching. These myocardial changes in patients with heart failure promote conduction delays and lead to ventricular arrhythmias.
Pacemakers have been the standard treatment for heart block since 1958. The technology for pacemakers has evolved from simple pacing devices to biventricular or cardiac resynchronization devices. These new devices that coordinate the contraction of the ventricles and improve cardiac output are used in a select group of patients with heart failure. In the late 1960s, the implantable cardioverter defibrillator (ICD) was developed to treat patients at risk for SCD. The first successful implantation in a human occurred in 1980. Since then, ICD technology has continued to evolve. Use of device therapy to prevent SCD and to correct dyssynchrony in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Left ventricular dyssynchrony results from intraventricular conduction abnormalities evidenced by a wide QRS on electrocardiograms. The most common intraventricular conduction delay is left bundle branch block, which occurs in as many as 25% of patients with moderate to severe heart failure.
Three multicenter prospective clinical trials-Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)-addressed the prophylactic effectiveness of devices in decreasing mortality in patients with heart failure without ventricular arrhythmias.
These 3 trials all provide evidence of device effectiveness but do not conclusively indicate which device is superior in preventing mortality in patients with heart failure.
The 3 trials varied in the devices used, study designs, and patients' level of disease severity. All 3 trials showed decreased mortality with devices in patients with heart failure without electrical disturbances. These trials were the first demonstrations of the effectiveness of devices for patients without previous ventricular arrhythmias. In this article, we review and clarify the results of these 3 trials. We review the similarities and differences in the studies and discuss the nursing implications of the findings.
Use of device therapy to prevent sudden cardiac death in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Three multicenter prospective clinical trials-Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)-were conducted to determine the effectiveness of devices in reducing mortality in patients with heart failure who did not have a history of ventricular arrhythmias. The 3 trials varied in the devices used, the population of patients included, and the study designs. In SCD-HeFT, implantable cardioverter defibrillators were more effective than pharmacological therapy in preventing mortality among patients with mild to moderate heart failure. In COMPANION, cardiac resynchronization therapy alone and cardiac resynchronization therapy plus an implantable cardioverter defibrillator were more effective than optimal drug treatment in reducing morbidity and all-cause mortality in patients with moderate to severe heart failure. In CARE-HF, cardiac resynchronization therapy alone was more effective than optimal drug treatment in reducing all-cause mortality in patients with moderate to severe heart failure. No direct comparison of the devices used has been done. These 3 clinical trials provide clear evidence that device therapy is beneficial for some patients with heart failure, even patients who do not have a history of ventricular arrhythmia.
As mortality from myocardial infarction has decreased because of improved treatment, the number of persons living with heart failure has increased. Heart failure is the only major cardiovascular disorder that is increasing in incidence and prevalence; roughly 5 million people in the United States have this disorder. Heart failure is a major cause of sudden cardiac death (SCD). More than half of the deaths due to heart failure are from SCD; the remainder are due to progressive heart failure. The most important preexisting condition and the best predictor of SCD is left ventricular dysfunction, the underlying cause of heart failure. Ventricular tachycardia reentry circuits occur when the left ventricle is enlarged because of ischemia, scarring, or muscle stretching. These myocardial changes in patients with heart failure promote conduction delays and lead to ventricular arrhythmias.
Pacemakers have been the standard treatment for heart block since 1958. The technology for pacemakers has evolved from simple pacing devices to biventricular or cardiac resynchronization devices. These new devices that coordinate the contraction of the ventricles and improve cardiac output are used in a select group of patients with heart failure. In the late 1960s, the implantable cardioverter defibrillator (ICD) was developed to treat patients at risk for SCD. The first successful implantation in a human occurred in 1980. Since then, ICD technology has continued to evolve. Use of device therapy to prevent SCD and to correct dyssynchrony in patients with heart failure is expanding on the basis of evidence from recent clinical trials. Left ventricular dyssynchrony results from intraventricular conduction abnormalities evidenced by a wide QRS on electrocardiograms. The most common intraventricular conduction delay is left bundle branch block, which occurs in as many as 25% of patients with moderate to severe heart failure.
Three multicenter prospective clinical trials-Sudden Cardiac Death in Heart Failure (SCD-HeFT); Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION); and Cardiac Resynchronization-Heart Failure (CARE-HF)-addressed the prophylactic effectiveness of devices in decreasing mortality in patients with heart failure without ventricular arrhythmias.
In SCD-HeFT, ICDs were more effective than pharmacological therapy in preventing mortality among patients with mild to moderate heart failure.
In the COMPANION trial, cardiac resynchronization therapy (CRT) alone and CRT plus an ICD (CRT-D) were equally effective in patients with moderate to severe heart failure, and both were more effective than optimal pharmacological treatment (OPT).
In the CARE-HF trial, CRT alone was more effective than OPT in reducing all-cause mortality in patients with moderate to severe heart failure.
These 3 trials all provide evidence of device effectiveness but do not conclusively indicate which device is superior in preventing mortality in patients with heart failure.
The 3 trials varied in the devices used, study designs, and patients' level of disease severity. All 3 trials showed decreased mortality with devices in patients with heart failure without electrical disturbances. These trials were the first demonstrations of the effectiveness of devices for patients without previous ventricular arrhythmias. In this article, we review and clarify the results of these 3 trials. We review the similarities and differences in the studies and discuss the nursing implications of the findings.
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