ORLANDO, Florida The armamentarium of devices to shock and assist the pumping action of the heart seems to have grown rather full, with seemingly little room for new ones. Pacemakers, defibrillators, ventricular assist devices and even the artificial heart have provided an increasing range of technologies for supporting and retaining important functions and even substituting for the heart.
But there is space for at least one additional device in this sector, according to research unveiled in an abstract at last month's 2003 scientific sessions of the American Heart Association (AHA; Dallas, Texas) and presented by Daniel Burkhoff, MD, PhD, associate professor of medicine at Columbia University's College of Physicians and Surgeons (New York). Burkhoff is co-author of the report and a consultant to the device's manufacturer, Impulse Dynamics (Orangeburg, California).
The device is called the Optimizer II, with its closest antecedent being the pacemaker but working in a somewhat different fashion and performing a distinctly different function, Burkhoff told Cardiovascular Device Update. The Optimizer II is an implantable device, similar in size and shape to a pacemaker, but that's where the similarity ends, he said. A pacemaker works primarily on a heart with slowed rhythms, correcting that problem by initiating contractions when a beat has been missed. By contrast, the Optimizer II senses when a beat has already started, and then sends an electrical signal to strengthen the contraction of the heart.
"A pacemaker tells the heart when to beat; the Optimizer helps the heart beat stronger," said Burkhoff in a capsule summary of the difference between the two technologies. He also made a distinction between what the Optimizer II does and one of the newest pacing modalities, cardiac resynchronization therapy (CRT) for treating one of the subgroups of heart failure patients. "CRT appears to be useful in about 20% to 30% of people with heart failure who also have an abnormality in the timing [of] heart chamber contractions." Burkhoff said. "Our goal is to develop a treatment for the greater number of heart failure patients who don't necessarily have a problem with synchrony."
In the study rolled out at the AHA meeting, the research enrolled 25 patients with moderately severe heart failure from medical centers in Austria, Germany and Italy. Patient eligibility included a heart ejection fraction of less than 35%, compared to a normal ejection fraction of 60%. Additionally, the patients had poor exercise tolerance they could walk for short distances only before becoming extremely fatigued. During the implantation procedure, physicians tested the device to ensure the patients' response to the signals delivered by the Optimizer II. Two patients did not respond, so they did not receive the device. In the 23 study patients, the device was activated three hours a day for eight weeks, with the patients then receiving follow-up testing. At the end of the follow-up period, their ejection fractions increased from an average of 22% to 26%, a significant increase. And the average distance patients could walk in six minutes increased from 1,348 feet to 1,526 feet, also considered a significant increase. Further, patients reported a better quality of life.
While acknowledging this is a pilot study, small in size and the results possibly explainable as a placebo effect, Burkhoff said that if further studies prove the benefit to be real, it is "comparable to those [benefits] seen in prior studies of CRT." He added, "This [study] encouraged us that the ultimate impact on patients' quality of life would also be similar to that achieved with CRT, with the hope that this treatment will be applicable to a larger percentage of the heart failure population." Burkhoff put that population at about 1 million in the U.S. alone.
Burkhoff said that the technical concept of early identification of electrical activity "in isolated pieces of muscle" has been known probably for 40 years, but only recently was found to have applications for the heart. Impulse Dynamics, he said, has been developing the Optimizer device over the past four years and has won CE marking in Europe, where randomized investigational work is going on before commercialization is achieved there. Meanwhile, the company has applied for an investigational device exemption in the U.S. so that Burkhoff and a large team of other cardiologists can conduct a more robust trial of the device. If successful and ultimately commercialized in the area of heart disease, further applications will be explored, he said, primarily in diabetes and obesity. But that initial success won't come quickly, he acknowledged. "It is a very complex and long path to develop treatments for heart failure."