Laser Heart Drill Provides Relief

Friday, November 17th 2000, 12:00 am

By: News On 6

NEW ORLEANS (AP) â€” Using a laser to drill tiny holes in the heart seems to produce years of relief from disabling chest pain, even though experts still cannot explain for sure why it works.

The procedure, called transmyocardial revascularization, or TMR, became available for routine use last year. However, some doctors remain skeptical and wonder if the apparent benefit is an illusion.

The latest findings, released Tuesday, came from the first long-term follow-up of patients getting the treatment. It found that the benefits last at least five years and often longer.

The patients were treated with a carbon dioxide laser developed by PLC systems of Franklin, Mass., which sponsored the review. The findings were presented by Dr. Keith Horvath of Northwestern University Medical Center at a meeting in New Orleans of the American Heart Association.

The procedure is intended primarily for patients who cannot undergo balloon angioplasty or coronary bypass surgery, the two leading procedures for increasing blood flow to the heart muscle when clogged arteries choke off the supply.

Doctors rate the intensity of chest pain, known as angina, on a scale of 1 to 4. Before treatment, the patients' average angina scores were 3.7.

One year after treatment, their scores had improved to 1.5. And after an average of five years of follow-up, they were virtually unchanged at 1.6. Seventeen percent of the patients had no chest pain at all after five years. Some still felt fine eight to nine years after the procedure.

The treatment requires doctors to open the chest, expose the heart and use the laser to burn 10 to 50 holes in the heart. Doctors once thought that the holes served as new blood channels. But this idea has been largely rejected, since the holes quickly fill in after the treatment.

Proponents now say they think it works by prompting the heart to improve its own blood supply. They say the drilling probably triggers the release of growth proteins, and these force the muscle to sprout new blood vessels, which carry in oxygen and relieve the pain.

Another idea is that the damage caused by the laser destroys nerves in the heart. Pain goes away, even though the underlying problems remain.

However, during a session at the heart meeting, Dr. David Faxon of the University of Chicago raised another often-mentioned possibility.

``Why couldn't the results be an enormous placebo effect?'' he asked Horvath.

The patients knew they were undergoing a major procedure that doctors believed would help them. Perhaps, the thinking goes, the patients simply imagined their improvement.

Such illusions are common in medicine, especially with treatments intended to stop pain. Recently doctors tested a competing form of the treatment that uses a laser on a tube threaded into the heart to drill holes from the inside out.

Patients were randomly assigned to get real laser treatment or make-believe therapy. Those who got the laser improved dramatically, but so did patients receiving the mock drilling.

However, Horvath replied that a placebo effect should have worn off long ago. ``We saw improvement that people cannot will to happen,'' he said.