Angina patients whose intense, often suffocating chest pains can not be reliably relieved by medication or invasive treatments can gain significant pain reduction from a little-used medical procedure that appears to increase heart blood supply, a new study has found.
In the first controlled trial of the painless, non-invasive treatment known as enhanced external counterpulsation (EECP), patients experienced less frequent angina pain and had less need for nitroglycerin to control pain than did a control group of angina patients.
The results are published in the June issue of the Journal of the American College of Cardiology.
Nationally, about 15 million people suffer from angina, more than two million chronically. The number is expected to increase as the population ages. And for almost all of these people, neither drugs nor vascular surgery provide complete relief.
"To find something that is very safe and effective in this group of patients is very gratifying," said Tony Chou, MD, assistant professor of medicine at UC San Francisco, a clinical cardiologist at UCSF Stanford Health Care and co-author of the report in the cardiology journal.
Patients undergoing the EECP treatment lie on a table and wear a series of cuffs on their legs. At the precise moment of every heartbeat when the heart relaxes, the cuffs briefly inflate. This is thought to reduce the heart's workload, increase its pumping efficiency and improve cardiac bloodflow. The treatment usually involves 35 one-hour sessions.
"The angina patients we treated with EECP have not found relief from any other treatment -- from medications, angioplasty or surgery. They are a very frustrated group of patients for whom we don't have anything to offer. This treatment functions almost like a very good medication," Chou said.
The technique, largely developed in China, has been tested clinically in various forms over the past 30 years, with many reports of major success. But until now, no rigorous controlled study of the treatment had been undertaken.
In the multicenter trial conducted at UCSF, Harvard Medical School, Columbia-Presbyterian Medical Center, Yale University School of Medicine and three other sites, 71 angina patients with documented coronary artery disease were given 35 one-hour EECP treatments over a four-to-seven-week period, while 69 similar patients were "treated" in EECP cuffs without adequate inflation to affect blood flow. Neither the participating patients nor the physicians who studied their progress knew whether they were receiving the active therapy or the control.
Compared to the control group, the "active" EECP treatment patients experienced significantly less frequent angina attacks. Although the two groups were able to exercise on a treadmill for about the same length of time, the EECP-active group was able to do so for longer periods without provoking abnormal electrocardiograms, the researchers reported.
Use of nitroglycerin in the active group was lower, but not by a statistically significant degree.
In an editorial assessing the treatment in the same issue of the cardiology journal, Richard Conti, MD, of the University of Florida, wrote that EECP has "great potential and could be particularly applicable to patients who are not candidates for revascularization procedures like bypass surgery or balloon angioplasty. . ."
The precise mechanism by which EECP exerts its long-term beneficial effect is unknown, said Richard Nesto, MD, associate professor of medicine at Harvard Medical School and senior author of the paper in the Journal of the American College of Cardiology.
"This will open up new scientific areas," he said. He suggested that EECP may improve the function of the endothelium, the cells that line the inner walls of blood vessels and help regulate their function.
"Another potential mechanism could be the recruitment of collateral coronary vessels," he added.
UCSF's Chou explains the EECP treatment and its benefits this way: "The heart, unlike the rest of the body, gets its blood flow when it is relaxing. When the heart squeezes, it forces blood throughout the body, but not to itself. It is during the relaxation, or diastole phase that the coronary arteries are fed. So, this device times the counterpulsation wave so that it occurs right during the heart's relaxation phase, giving a surge of blood back to the heart that it otherwise would not be able to develop. The thought is, if you do this over and over, patients would be able to achieve improved blood flow."
The research team plans next to undertake studies to clarify if and how much heart blood flow is improved by the EECP technique.
Lead author on the journal report is Rohit R. Arora, MD, assistant professor of medicine at Columbia University. Co-authors, along with Chou and Nesto, are Diwakar Jain, MD, of Yale University School of Medicine; Bruce Fleishman, MD, of the Grant/Riverside Methodist Hospital, Columbus, Ohio; Lawrence Crawford, MD, of the Pittsburgh Medical Center; and Thomas McKiernan, MD, of Loyola University Medical Center.
The research was funded by a grant from Vasomedical, Inc. which manufactures the EECP device used in the trial.
Materials provided by University Of California, San Francisco. Note: Content may be edited for style and length.
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