(Circulation. 2000;102:e9036.)
© 2000 American Heart Association, Inc.
Cardiovascular News |
Cardiovascular News
1 Circulation Newswriter
Direct Myocardial Revascularization a "Placebo Effect," According to Study Chief
The chief of the first blinded study of percutaneous direct myocardial revascularization said his results indicate that the controversial treatment has a profound placebo effect that has previously been confused with therapeutic benefit in unblinded studies. Martin Leon, MD, a cardiologist at Lenox Hill Heart and Vascular Institute in New York, NY, called the perceived benefits in previous studies "an exaggerated placebo effect."
Dr Leon revealed the results of the Direct Myocardial Revascularization in Regeneration of Endomyocardial Channels Trial (DIRECT) at Transcatheter Cardiovascular Therapeutics 2000, a meeting held in Washington, DC, on October 19, 2000. He was the principal investigator of the 14-center study in which 298 patients were randomly assigned to either low-dose or high-dose laser treatment or to a placebo trial in which laser treatment was realistically simulated. Patients did not know which treatment they received.
Dr Leon told the Wall Street Journal, "This was a dead-on negative trial." All patients reported an improvement in symptoms and achieved better scores on a treadmill test given 6 months later. However, there was no difference among the groups. In fact, he told the Journal, the placebo group did the best when measures of improvement in angina class were considered.
There are 2 methods of direct myocardial revascularization. The first is surgical and involves opening the chest and punching holes from outside the heart into the myocardium using a laser. A second method uses a catheter to thread the laser into the heart and makes the holes in the myocardium from the inside the heart.
The procedure has been used in patients for whom surgery or angioplasty are not possible and medication is no longer working. In the DIRECT study, Dr Leon was also testing a new direct myocardial revascularization system made by Biosense, a subsidiary of Johnson & Johnson. A phase I trial of the system demonstrated improvement in patients who underwent the procedure; however, at the time, Ran Kornoski, MD, of Washington Hospital Center in Washington, DC, said only a blinded trial would enable physicians to determine if the treatment worked and how much.
There has been much controversy on what causes the effects seen in patients who undergo the procedure. At first, surgeons thought that punching the holes simply nourished the myocardium with more blood. However, the channels punched by the laser tend to heal very quickly. Later theories revolved around the notion that the act of punching the holes in the heart muscle encouraged angiogenesis, which resulted in more blood vessels bringing blood to the heart.
However, Dr Leon told the Journal that he felt the previous studies should be called into question because they did not control for the placebo effect. Future studies must also come into question unless they control for the effect, he said.
In 2 studies in the September 30, 1999, issue of the New England Journal of Medicine, researchers compared transmyocardial revascularization with medical therapy. In each instance, they found that the laser therapy resulted in greater symptom improvement than medical therapy (N Engl J Med. 1999;341:1029–1036 and N Engl J Med. 1999;341:1021–1028). Two lasers to perform the procedure have been approved by the US Food and Drug Administration.
Medicare Enrollment Increased by 1.1 Million in Year Ending December 1999
Medicaid enrollment increased by 1.1 million between December 1998 and December 1999, according to a report released by the Kaiser Family Foundation on October 13, 2000. The increase came after the federal and state program to provide health care to the indigent saw numbers dropping between 1996 and 1998. The decreases came during a period when reform in the welfare system saw fewer people claiming aid from assistance programs nationwide.
Although numbers increased, federal officials warned in an article in the October 17, 2000 issue of the Washington Fax that they simply represent a return to Medicaid coverage levels before welfare reform. During the initial periods of that movement, families eligible to retain Medicaid coverage lost it. Federal officials want the states to simply and streamline application processes to make it easier for those who qualify to obtain coverage.
New Mouse Site Links Researchers
A new website created by researchers at Baylor College of Medicine in Houston and funded by the National Institutes of Health is designed to help researchers collaborate on identifying the function of genes identified by the Human Genome Project.
"An altered gene can disrupt the physiology and behavior of a mouse in unpredictable ways. As a result, it often requires the combined energies of many laboratories to fully characterize what has gone wrong with each mouse," said Jeffrey Noebels, MD, professor of neurology and molecular and human genetics at Baylor College of Medicine. Dr Noebels and Caleb Davis, a programmer in the department of neurology, developed the site together.
Scientists can use the website to identify mice they need for their studies and to post their own mice for others to examine. They can also collaborate on studies using the website or ask that they be contacted when new mice are entered. The new website can be found at www.mymouse.org
Head Injuries Linked to Alzheimer’s Disease
Serious head injury in early adulthood may be associated with Alzheimer’s disease later in life, according to researchers at the National Institute on Aging and Duke University. In a study published in the October 24, 2000, issue of the journal Neurology (2000;55:1158–1166), Brenda L. Plassman, PhD, of Duke, Richard J. Havlik, MD, MPH, of the National Institute on Aging, and others described the association in a study they conducted of World War II veterans who were hospitalized during their period of service with a diagnosis of head injury or an unrelated condition.
Studying the records of male Navy and Marine veterans allowed the researchers to evaluate subjects in whom the head injury had been documented, thus eliminating the potential bias of subject recall. A total of 548 veterans who suffered head injury and 1228 veterans without head injury were included in the study.
The researchers then painstakingly identified the veterans who had dementia and those who specifically had Alzheimer’s disease. When they compared the numbers of people with Alzheimer’s in the group with head injuries with the group that had no head injuries, they found a 2-fold increased risk of Alzheimer’s and dementia in those who had suffered a moderate head injury. And, they said, the risk increased with the severity of the injury.
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