Besides maintaining optimal electrical stimulation to the heart, these CRT-D (cardiac resynchronization therapy with defibrillation) devices are giving cardiologists a new view of subtle changes in a key measurement of heart health -- heart rate variability. Patients with little variability -- whose hearts are unable to appropriately react to external stimuli by regulating their beating action -- are known to be at higher risk of suffering a heart attack. The new insight from CRT-D devices is possible because they record detailed data on heart function 24 hours a day.
These new findings are important for two reasons, the researchers said. First, the collected information appears to more accurately identify high risk patients who would benefit from early and aggressive therapy. Secondly, the devices provide cardiologists with objective information about the health status of their patients, information that can be frustratingly difficult to obtain in a typical clinical setting in this medically diverse group of patients, the researchers said.
The results of the study were presented by Duke cardiologist Roosevelt Gilliam, M.D., March 7, 2005, at the annual scientific session of the American College of Cardiology in Orlando. "When you talk to heart failure patients, many times their perceptions of how they feel do not match with their actual clinical status, which can make it difficult for cardiologists to get a true idea of how the disease is progressing," said Gilliam, chief of electrophsysiology at Duke. "This study shows that changes in heart rate variability just might be better in picking out those people at highest risk."