Related Experiment Videos
Cardiac resynchronization: a novel therapy for heart failure
1Cardiovascular Division, Department of Medicine, University of Pennsylvania Health System, Philadelphia, PA 19104.
Insights
Biventricular pacing shows promise for improving heart function and reducing mortality in congestive heart failure patients with conduction delays. Ongoing trials will confirm its long-term benefits.
Area of Science:
- Cardiology
- Biomedical Engineering
Background:
- Congestive heart failure (CHF) morbidity and mortality remain high despite medical advances.
- Intraventricular conduction delays are common in CHF patients and linked to worse outcomes.
- Previous dual-chamber pacing showed limited benefits in CHF.
Purpose of the Study:
- To evaluate the efficacy of biventricular pacing in CHF patients with conduction abnormalities.
- To assess improvements in hemodynamic function, exercise capacity, and mortality.
Main Methods:
- Biventricular pacing (cardiac resynchronization therapy) was investigated.
- Studies included patients with CHF and intraventricular conduction delay.
- Prospective, randomized, controlled trials (MIRACLE, COMPANION) are validating long-term efficacy.
Main Results:
- Biventricular pacing demonstrated acute hemodynamic and functional benefits.
- Improvements in cardiac index, blood pressure, and functional class were reported.
- Longer-term follow-up showed sustained benefits.
Conclusions:
- Biventricular pacing offers significant advantages over conventional pacing for selected CHF patients.
- It improves cardiac function and potentially reduces mortality in CHF with conduction delays.
- Further validation through large-scale trials is ongoing.
Abstract:
Despite advances in medical therapy for patients with congestive heart failure, morbidity and mortality remain high. Conduction abnormalities, such as left bundle branch block, right bundle branch block, and nonspecific conduction delay, are observed commonly in patients with dilated cardiomyopathy. In patients with heart failure, the presence of intraventricular conduction delay is associated with more severe mitral regurgitation and worsened left ventricular systolic and diastolic function, and is an independent risk factor for increased mortality. Conventional dual-chamber (right atrial and right ventricular) pacing with a short atrioventricular delay was initially introduced as therapy for patients with advanced congestive heart failure to improve diastolic dysfunction and reduce mitral regurgitation. The acute beneficial hemodynamic effects observed in early, uncontrolled studies were not confirmed in subsequent randomized, controlled studies with longer follow-up. Cardiac resynchronization with novel biventricular (left and right ventricular) pacing systems has resulted in hemodynamic and functional benefits in patients with congestive heart failure and an underlying intraventricular conduction delay. Improvements in cardiac index, systolic blood pressure, and functional class have been reported with biventricular pacing, both acutely and at more than 1 year of follow-up. These encouraging preliminary results with biventricular pacing in patients with congestive heart failure will be validated in two prospective, randomized, controlled trials, Multicenter InSync Randomized Clinical Evaluation (MIRACLE) and Comparison of Medical Therapy, Pacing, and Defibrillation in Chronic Heart Failure (COMPANION). These studies are designed to evaluate the long-term efficacy of biventricular pacing in improving exercise capacity and in reducing morbidity and mortality in patients with advanced, symptomatic congestive heart failure. (c)2001 by CHF, Inc.