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Experts Question Use of Laser Therapy for Angina -- Despite Promising Research Results

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WebMD Health News

Nov. 16, 1999 (Atlanta) -- Despite positive results from large-scale clinical trials, use of a relatively new type of laser treatment to relieve angina -- severe, chronic chest pain -- remains a hotly debated topic.

Two studies published in a recent issue of The New England Journal of Medicine showcase the benefits of transmyocardial revascularization (TMR), in which a laser is used to trigger the growth of new blood vessels in the heart. In the same issue, however, an accompanying editorial cautioned that without a better understanding of how TMR works, "the advisability of using [TMR] is questionable."

Editorial co-author Richard A. Lange, MD, tells WebMD that while studies "have shown that [TMR] is effective at relieving symptoms, what we don't have is objective evidence that it actually improves [heart function] or an idea of how it works." Lange is a professor at the University of Texas Southwestern Medical Center, Dallas.

The laser procedure is used only in patients whose angina is severe and has not responded to -- or cannot be successfully treated with -- traditional therapies such as drugs, angioplasty (surgical artery reconstruction), or bypass surgery. TMR is also controversial because of its risk: During clinical trials prior to the FDA?s August 1998 approval of TMR, some patients experienced severe arrhythmia (irregular heartbeat) -- and a small number died within a month of undergoing the procedure. Further research, however, has found no significant difference in one-year survival rates among patients who received TMR and those who did not.

Researcher Keith A. Horvath, MD, a researcher involved in the first study, defends TMR and its benefits. "There are both clinical and animal studies ... showing TMR does improve function. With echo [echocardiography, or ultrasound heart recordings], you can see the heart wall is actually contracting better," Horvath tells WebMD. Horvath is an assistant professor of cardiothoracic surgery at Northwestern University Medical School in Chicago.

Led by O.H. Frazier, MD, at Texas Heart Institute in Houston, Horvath's study involved patients with severe angina who could not safely undergo either angioplasty or coronary artery bypass. In the group that received TMR, 72% of patients experienced significant chest pain relief and a modest improvement in heart function. Survival rates at one year were similar for both the patients who received TMR and those who didn?t.

Lange tells WebMD that two other studies have not produced the positive results of the Texas study, which is why he and others remain cautious about recommending TMR. "What you're looking for in a therapy that's going to be effective is some consistency, and that's the thing we're lacking."

In the second reported study, researchers at 18 U.S. medical centers followed 275 patients with class 4 (the most serious) angina. Those who received TMR saw their angina improve and had lower hospitalization rates, but did not have improved heart function.

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