By Karla Gale

NEW YORK (Reuters Health) - The chest pain experienced by people with coronary artery disease is caused by restricted blood flow to the muscle of the heart. Now, researchers have shown that gene therapy can improve perfusion of the heart in patients with angina (news - web sites).

The gene therapy involves administering a harmless virus containing a gene for fibroblast growth factor (Ad5FGF-4) into the coronary arteries, to foster the growth of secondary branches -- or "collaterals" -- of the arteries.

The researchers previously found that Ad5FGF-4 therapy increased treadmill exercise time in patients with angina. "But we did not directly measure blood flow in the heart to prove we were growing new collaterals," lead investigator Dr. Cindy L. Grines told Reuters Health.

The current study, published in the Journal of the American College of Cardiology, was designed to directly measure perfusion of the heart by means of isotope imaging, after Ad5FGF-4 treatment.

Included in the study were 52 patients with angina that wasn't responding to drug treatment, and who were not good candidates for surgery. Thirty-five participants underwent Ad5FGF-4 treatment and 17 received inactive placebo treatment.

Eight weeks later, the area of poor perfusion in the heart was reduced by an average of 4.2 percent in the group that received active treatment, compared with a 1.6 percent reduction in the placebo group, the report indicates.

Moreover, an increase in area of impaired perfusion was seen in only 6 percent of patients who underwent gene therapy, versus 35 percent of the placebo group.

Also, the active treatment group tended to have a greater improvement in angina symptoms than did the control group, with 43 percent and 17 percent of subjects, respectively, no longer using nitroglycerin at 8 weeks after treatment.

After following the patients for one year, the investigators found that Ad5FGF-4 was well tolerated and had no permanent adverse effects.

Based on these promising results, Dr. Grines said, two larger trials are currently enrolling 450 patients each to gather more information on long-term outcomes of Ad5FGF-4 gene therapy.

SOURCE: Journal of the American College of Cardiology, October 15, 2003.