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COLUMBIA-PRESBYTERIAN MEDICAL CENTER
STUDY SUPPORTS SAFETY AND EFFICACY OF ENHANCED EXTERNAL COUNTERPULSATION
Noninvasive, Mechanical Treatment For Chronic Angina
ORLANDO, FLORIDA, NOVEMBER 11, 1997 -- Enhanced external counterpulsation (EECP), a noninvasive, outpatient therapy for chronic angina, is both safe and effective, according to a multicenter clinical trial led by Columbia-Presbyterian Medical Center.
The results of the trial, the first national, randomized, placebo-controlled study of EECP, were presented today at the annual meeting of the American Heart Association in Orlando, Fla.
Angina occurs when the coronary arteries become narrowed or obstructed and cannot deliver enough oxygen-rich blood to the heart muscle in response to exercise or other stress. The pain usually subsides with rest, but it can be quite debilitating and severely diminish one's quality of life.
Doctors generally prescribe medications, balloon angioplasty, or coronary artery bypass graft surgery, each of which increases blood flow within the coronary arteries and reduces the workload of the heart. However, about 20 percent of patients are not helped by these remedies. Furthermore, both angioplasty and bypass surgery are invasive and carry small but significant risks.
EECP, cleared by the FDA for clinical use in 1995, is a promising, nonsurgical alternative. The therapy is applied with three sets of blood-pressure-like cuffs that are placed around the patient's calves and lower and upper thighs. When the heart relaxes, the cuffs are inflated sequentially, from the calves upward, which blocks the flow of blood into the leg arteries and pushes venous blood in the legs toward the heart. When the heart contracts, the cuffs deflate simultaneously, allowing blood to flow back into the lower extremities. The net effect is to raise the blood pressure in the coronary arteries, which increases the flow of oxygen to the myocardium, explains study leader Rohit Arora, MD, who is Director of the Coronary Care Unit at Columbia-Presbyterian.
The timing of the inflation and deflation is critical, says Dr. Arora. The coronary arteries are distinct from other arteries in that they fill with blood when the heart relaxes (diastole); other arteries fill when the heart contracts (systole). Therefore, for EECP to have any effect on the coronary arteries, the cuffs must pulsate when the heart does not, hence the term "counterpulsation."
In the trial, 139 patients with coronary artery disease (CAD) and angina pectoris were randomized to receive either EECP or inactive counterpulsation (Sham). The patients ranged in age from 40 to 81, with a mean age of 63. Eighty-eight percent were male. About 58 percent of the patients had undergone angioplasty and/or bypass graft surgery. In addition, about 55 percent had residual multivessel CAD despite having underdone revascularization procedures. The treatment (EECP or sham therapy) was applied in 35 one-hour sessions over four to seven weeks. Patients were asked to keep a journal, recording frequency and intensity of chest pain, intake of nitroglycerin, and other quality-of-life measures, and to undergo pre- and post-treatment exercise stress tests. The stress tests measured both exercise duration and time to onset of STT depression (a sign of heart muscle ischemia), a more objective measure of exercise tolerance.
Data were presented today on the first 139 patients. EECP resulted in an increase in exercise duration, an increase in time to onset of STT depression, and a decrease in weekly episodes of angina. Placebo therapy resulted only in increased exercise duration.
"The trial demonstrates both the safety and efficacy of EECP in treating myocardial ischemia in patients with severe CAD, many of whom had failed prior bypass surgery or angioplasty," says Dr. Arora.
No serious complications occurred in either group. Two patients in the treatment group dropped out of the trial, complaining of leg discomfort. "Most patients feel only a little kick in the legs and thighs, but otherwise they are comfortable enough to read or listen to music during the treatment," reports Dr. Arora.
The researchers are not sure how EECP works. According to Dr. Arora, "The increased pressure may build collaterals to the blocked arteries, creating a natural bypass." In addition, the deflation of the cuffs creates a suction effect in the legs that is thought to ease the heart's workload.
"Additional long-term research is needed to define the optimal regimen for the application of EECP and the long-term benefits provided by this noninvasive technology," he says. Previous studies show that the effect of EECP can persist for at least three years.
The study was sponsored by Vasomedical, Inc., of Westbury, N.Y., which manufactures the EECP device.
Contact: Karin Eskenazi , 212/305-5587
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