The experimental drug vesnarinone could prolong the lives of hundreds of thousands of people who suffer from congestive heart failure, researchers announced yesterday.
The risk of death decreased 62 percent among patients who took the drug for six months, said Dr. Arthur Feldman, associate professor of cardiology at Johns Hopkins University School of Medicine and a director of the study, published in this week's New England Journal of Medicine.
"We don't know the effects over two or three years, but our suspicion is that the positive effects will continue," he said.
The drug offers hope to the nearly 3.5 million Americans who suffer from congestive heart failure by prolonging and improving the quality of their lives, he said.
Some health professionals said the drug warranted further investigation but questioned its promise.
An editorial in the journal written by Dr. Milton Packer of Columbia University, challenges, among other things, the way researchers evaluated patients' "quality of life." He could not be reached for comment.
"The drug is clearly interesting, and it may have great potential. But there are still major questions as to how it works, who will benefit and who will be harmed by it," said Dr. Stephen Gottlieb of Baltimore. He was asked to comment in his role as director of the cardiac care unit at the University of Maryland School of Medicine.
Congestive heart failure, a condition in which the heart muscle doesn't function adequately, affects about 6 percent of all Americans over age 65.
Half of those who have congestive heart failure die within one year of diagnosis, and 80 percent to 90 percent die within five years.
Vesnarinone works by promoting more powerful contractions of the heart muscle without increasing the heart rate. Other medicines that cause more powerful contractions also cause the heart to pump faster, Dr. Feldman said.
Vesnarinone also opens up the large arteries, facilitating blood flow, and has what Dr. Feldman termed "novel ancillary properties," the ability to promote survival.
In the study, which was conducted at 22 medical centers nationwide, 239 patients each took 60 milligrams of vesnarinone daily and 238 took placebos. Both groups also took regular medicines including blood vessel dilators, heart muscle contractors and diuretics.
Another portion of the study, involving 87 patients who were given 120 milligrams of vesnarinone a day, was discontinued when it was determined the higher dosage increased the mortality rate. Of that group, 16 patients died.
However, in those taking 60 milligrams, fewer people died than would have been expected. Thirteen patients died, compared with 33 taking placebos. Eighteen others taking 60 milligrams of vesnarinone experienced deteriorating heart conditions, compared with 33 taking placebos.
Side effects were detected in 2.5 percent of the patients taking 60 milligrams of the drug. Their white blood cell counts dropped, leaving them susceptible to infection. The cell counts returned to normal when the drug was discontinued.
That percentage seemed high to Dr. Gottlieb.
"When a patient is in a study, he is followed very, very carefully, so any changes are noted," Dr. Gottlieb said. "When the drug is in the marketplace, a patient isn't followed that carefully, and that [loss of white blood cells] is potentially of great concern."
Dr. Gottlieb also questioned the increase in deaths among the patient group that received 120 milligrams of vesnarinone daily. Sixty milligrams -- the difference in this study between the beneficial dosage and a potentially fatal dosage -- is not large, he said.
Because individuals metabolize drugs differently, even a small dose might be harmful, he said. "If 120 milligrams is bad for you in the study but 60 is OK, and if I metabolize 60 milligrams differently from you, that might be the same as giving me 120 milligrams."
Dr. Michael Bristow, a professor at the University of Colorado and one of the directors of the study, said the 62 percent decrease in death risk among those suffering from congestive heart failure is significant.
"Truly, the 'cure' for congestive heart failure is to take out the heart and replace it," he said. "But only about 2.5 percent of those who need a transplant can get it" because of a shortage of organ donors.
The third director of the study was Dr. William Parmley of the University of California at San Francisco.