For the first time in this country, an approved injectable drug will be used as an alternative to the stress test to evaluate the effects of suspected coronary artery disease.
The drug will make it possible for a "tremendous number of people," who cannot tolerate exercise up to peak levels, to be diagnosed for this disease, researchers said yesterday.
I.V. Persantine is a new intravenous form of oral Persantine, which has been used in this country for chest pain since the 1960s. The drug, also known as dipyridamole, will be available next month. It simulates the physiological effect of exercise by increasing blood flow.
I.V. Persantine is used in tandem with thallium, a radioactive dye, to allow a physician to detect possible blood flow abnormalities or blockages due to coronary artery disease in two sets of images taken three to four hours apart.
"The I.V. Persantine/thallium test does the work when the patient can't," said Dr. Jeffrey Leppo, a clinical investigator and director of nuclear cardiology at the University of Massachusetts in Worcester.
The drug will be beneficial to stroke, arthritis, asthma, peripheral vascular disease and lung disease patients, he said.
Dr. Charles A. Boucher is a clinical trial investigator at Massachusetts General Hospital in Boston and associate professor at Harvard Medical School. He said the test should be used with caution in patients with unstable angina, severe asthma or the sudden constriction of bronchial tubes and in those who have had recent heart attacks.
Nearly 5 million Americans have been diagnosed with coronary artery disease. About 500,000 Americans die from heart attacks annually, Boucher said.
Of even greater concern, he said, are the number of "clinically silent" cases of the disease, estimated to be as high as 3 million or 4 million.
The disease occurs when fatty deposits narrow the coronary arteries, causing a deficiency of oxygen-carrying blood in an area of heart tissue. If untreated, this can result in heart attack and death.
Side effects from I.V. Persantine/thallium testing usually are mild and brief, Leppo said. They can include chest pain, dizziness, headache, low blood pressure and nausea. Adverse effects usually can be rapidly reversed within minutes after administration of another intravenous drug, aminophylline.
The cost of I.V. Persantine ranges from $66 to $110 a patient, depending on weight.
"It may cost a little more than the exercise test, but it looks like it will be covered by reimbursement," said Lee Peterson, a representative of the Du Pont Merck Pharmaceutical Co., which will market, manufacture and distribute the intravenous drug in the United States. The drug was approved in Canada a year ago and has been used in the United Kingdom since 1987.