Comparative of Markers of Oxidative Stress Present Pre and Post Cardiac Resynchronization Therapy Outcome Predictors

Congestive heart failure (CHF) is a common diagnosis with significant clinical impact. Although medical therapy exists, many patients on optimal medical treatment are still highly symptomatic. About 1/3 of these patients have a condition known as "dyssynchrony", where the walls of the heart beat in an uncoordinated way, causing worsening of CHF symptoms. A newer therapy known as cardiac resynchronization therapy (CRT) has been successful in decreasing symptoms in these dyssynchronous patients. It involves surgical placement of a pacemaker containing 3 wires- one in the top part of the heart (atrium) to coordinate the top and bottom parts of the heart beat, and two on the bottom to coordinate the bottom parts of the heart beat (ventricles). This treatment, however, does not work for up to 1/3 of patients with dyssynchrony.

Recent studies have found that CHF is associated with increased oxidative stress. This is a condition where abnormal oxygen forms are produced. These forms harm the cells of the heart, causing them to beat abnormally and causing damage to the heart muscle. We would like to see if levels of these forms improve after CRT, and if they can be measured early after surgery to predict who will and who will not benefit from surgery.

In this study, we will compare blood markers of oxidative stress between patients with CHF and an already-collected set of control patients to confirm these levels are elevated at baseline. Then, we will perform CRT surgery and implant pacemakers in the CHF patients. At 1 week and 3 months postoperatively, we will measure blood markers again, and see if they have improved in patients whose symptoms have improved. Patients will undergo echocardiograms to document their abnormal hearts, do a 6 minute hall walk to measure their exercise tolerance, and take a standardized questionnaire to measure their symptoms of CHF. These test results will be compared pre and post CRT to assess response to therapy.