Now, researchers at Cedars-Sinai Medical Center have conducted the first study to compare how well a non-invasive imaging procedure performed with a medication-induced stress test identified women and men at high risk of death from heart disease. The findings, published in the April 2nd issue of the Journal of the American College of Cardiology, examine adenosine stress myocardial perfusion scans and show that women have as great a risk of death from heart disease as men for every kind of scan abnormality. In addition, the study is the largest prognostic study of adenosine stress reported to date, and the first to show that diabetic women have a higher risk of death from heart disease than diabetic men or other patients without diabetes.
"Importantly, our findings show that the adenosine stress scan provides a quick, safe, and effective means for identifying both women and men with potentially fatal heart disease," said Dr. Daniel Berman, Director of Cardiac Imaging at the S. Mark Taper Foundation Imaging Center at Cedars-Sinai Medical Center. "The key is to identify the patient at risk. Once we know that high risk is present, there are a variety of effective therapies, from medical therapy to surgery, that can be used to effectively decrease this risk."
The stress test, technically called adenosine sestamibi myocardial perfusion SPECT (MPS), is commonly used to identify the presence of coronary artery disease, a condition in which the arteries serving the heart are "narrowed" due to a build-up of fatty deposits called plaques. Adenosine, a substance that is present in everyone in low concentrations, is used to provide a cardiac stress test when patients are unable to exercise adequately. Adenosine works by dilating the heart’s arteries (coronary arteries), causing the flow of blood to the heart muscle to increase. Once the heart’s arteries are dilated, a small amount of sestamibi, a radioactive imaging agent, is injected and concentrates in the heart according to blood flow, emitting signals that are captured by a special type of camera. Because blood flow cannot increase adequately when the arteries are narrowed, the images show the parts of the heart that are not getting enough blood.
These images provide information about the extent of heart disease, so that cardiologists plan the best treatment option for their patients.
To determine whether adenosine MPS provided comparable information between women and men regarding risk of death from heart disease, the investigators examined the medical records of 2,656 consecutive women and 2,677 men who had undergone the test at Cedars-Sinai between 1991 and 1998. Patients were then followed-up for an average of 27 months.
"Our study revealed a greater mortality risk after adenosine stress in both women and men than previously reported with exercise stress in every category of scan findings," said Dr. Berman.
During follow-up, 117 cardiac deaths occurred in women as compared to 164 deaths in men. When the scans were normal, the cardiac death rate was low for both women and men. Compared to men, the investigators found that women had fewer abnormalities on their scans. Although the overall rates of death were lower in women than in men, statistical analysis revealed that the death rate in women was similar to those of men in each of the scan categories.
Among male and female patients with heart disease, there were 1,222 who also had diabetes. Female diabetics were found to be at increased risk of cardiac death in each category of MPS abnormality compared to male diabetics or to all the non-diabetic patients. Also, using statistical methods to adjust for baseline differences in groups, the investigators found that diabetics taking insulin died at a much higher rate in all MPS scan categories than those who were non-insulin dependent or than non-diabetic patients.
"This study is the first to show an increased risk of death for any MPS scan result in insulin dependent patients and that female diabetics are at higher risk than diabetic men in each category of scan finding," said Dr. Berman. "Our findings in both diabetics and non-diabetics show that adenosine MPS can be very effective in establishing mortality risk in patients who are unable to exercise and in helping determine who needs the most aggressive therapy."
Cedars-Sinai Medical Center is one of the largest non-profit academic medical centers in the Western United States. For the fifth straight two-year period, Cedars-Sinai has been named Southern California’s gold standard in health care in an independent survey. Cedars-Sinai is internationally renowned for its diagnostic and treatment capabilities and its broad spectrum of programs and services, as well as breakthrough in biomedical research and superlative medical education. Named one of the 100 "Most Wired" hospitals in health care in 2001, the Medical Center ranks among the top 10 non-university hospitals in the nation for its research activities.
Journal
Journal of the American College of Cardiology