This study will explore which characteristics of patients with heart failure will likely predict improvement after cardiac resynchronization (CRT), implantation of a pacemaker to improve heart function. In spite of major medical advances, about 30% to 40% of patients with heart failure do not respond to CRT, and the reasons are not well understood. This study will involve magnetic resonance imaging (MRI), electrocardiogram (ECG), and echocardiography techniques to let researchers examine what may influence response to CRT.
Patients ages 18 and older with a left ventricular disorder and who are not pregnant or breastfeeding may be eligible for this study. Initial evaluation will take 5 to 6 hours. A blood sample of about 2 tablespoons will be collected, and several procedures will be performed. MRI uses a strong magnetic field and radio waves to obtain images of body organs and tissues. For that procedure, patients will lie on a table that slides into the enclosed tunnel of the scanner and be asked to lie still. They will be in the scanner for 30 to 90 minutes. As the scanner takes pictures, patients will hear knocking sounds, and they may be asked to hold their breath intermittently for 5 to 20 seconds. During part of the scan, a drug called gadolinium will be given intravenously (IV), to make the heart easier to see. Patients will be able to communicate with the MRI staff at all times during the scan. At any time, patients may ask to be moved out of the machine. Patients having metal in their body that interferes with the MRI scanner should not have this test. During the procedure, an ECG machine will monitor the heart, through wires connected to pads on the skin. Patients will have an echocardiogram, in which sound waves look at the heart. A small handheld probe will touch the chest and abdomen, and an IV tube may be inserted to inject a contrast drug to improve the quality of heart images. Patients will have a cardiopulmonary stress test (treadmill test) and a 6-minute walk test, both before pacemaker implantation and then 6 months afterward. Also before and after pacemaker implantation, patients will complete the Minnesota Living with Heart Failure Questionnaire, regarding the impact of heart failure on patients' lives. The follow-up visit will take 3 to 4 hours.
| Estimated Enrollment:
| Study Start Date:
||July 28, 2006
| Estimated Study Completion Date:
||May 29, 2007
Many patients with heart failure benefit from cardiac resynchronization therapy (CRT) which involves implantation of a pacemaker to improve the coordination of heart function. However, approximately 30-40% of patients fail to respond to this therapy with current selection criteria. We hypothesize that patients with echocardiographic and MRI measures of a high degree of LV mechanical dyssynchrony are more likely to benefit from CRT than patients with less baseline dyssynchrony. Severe LV remodeling as measured by MRI may also predict patients less likely to benefit from therapy. In addition, myocardial fibrosis/scarring as measured by MRI delayed enhancement imaging may predict segments or subjects less likely to respond to CRT even in patients without ischemic heart disease. In this study, patients with New York Heart Association class III - IV heart failure will undergo imaging and stress testing prior to CRT pacemaker implantation and 6 months later to determine predictors of response. Considering the complexity of the protocol and novelty of some aspects of the MRI examination, we consider this an exploratory observational protocol.