New screening tool can identify “silent coronary artery disease at an early stage in patients with diabetes The preliminary results of a groundbreaking study show that non-invasive imaging with Cardiolite(R) can identify "silent" coronary artery disease (CAD) at an early stage in diabetes patients — a high-risk population who often do not exhibit any apparent symptoms of heart disease. If confirmed, these research findings, presented last week at the Annual Scientific Session of the American Society of Nuclear Cardiology (ASNC), could pave the way for evidence-based guidelines for selectively screening these at-risk patients, potentially allowing for earlier intervention and saving many from premature heart attack or death.
Heart disease is the leading cause of death for the nearly 16 million Americans with type II diabetes — whose risk is two to four times that of the general population. Identifying coronary artery disease in these patients is difficult because many have no apparent "chest pain" symptoms. As a result, this so-called silent ischemia may go undiagnosed until symptoms of late-stage heart disease occur, including heart attack and cardiac death.
"These preliminary results are very important because recent studies have shown that patients with diabetes are still not fully aware of their risk for heart disease despite the fact that it is their leading cause of reduced life expectancy," said Frans J. Th. Wackers, M.D., professor of medicine, Yale University School of Medicine, who designed the study. "If these findings are confirmed, selectively screening these patients early with Cardiolite can help identify CAD in patients with no outward symptoms, potentially protecting many from more severe coronary events."
The study — Detection of Ischemia in Asymptomatic Diabetics (DIAD) — is the first multi center study to detect "silent" ischemia (heart disease) in patients with diabetes. Last weeks preliminary analysis of 522 patients represents initial results of this two-year study. In this data set, twenty- six percent of patients had an abnormal Cardiolite(R) (Kit for the Preparation of Technetium Tc99m Sestamibi for Injection) test suggesting "silent" CAD. Of those exhibiting an abnormal finding, 83 percent (114 patients) were found to have abnormal blood flow, while the remaining 17 percent (23 patients) were found to have other abnormal findings such as depressed left ventricular ejection fraction, another measure of heart health. These results were made more remarkable by the absence of CAD symptoms in all patients tested.
"As the doctors who see patients with diabetes every day, we know that many don’t display the classic symptoms of heart disease, making it difficult to detect ischemia before the onset of advanced and symptomatic disease," said Paul S. Jellinger, MD, former president of the American Association of Clinical Endocrinologists. "Given this significant diagnostic challenge and the disproportionate threat CAD poses to this patient population, identifying tests that assist in detecting heart disease at an early stage are critical. Needless to say, today’s results are an encouraging first step."
The prospective study involves more than 1,000 patients with type II diabetes aged 50 to 75 years with no known coronary artery disease. Enrolled patients were randomized to receive Cardiolite, the leading stress myocardial perfusion imaging (stress MPI) agent, and five year follow-up, or follow-up alone. Prior studies have shown Cardiolite to be an accurate predictor of major cardiac events in patients with diabetes known to have heart disease.
Stress MPI is a nuclear cardiology procedure that uses a radiopharmaceutical, such as Cardiolite, to measure blood flow to various structures of the heart. Patients undergo a Cardiolite study both to diagnose heart disease as well as to assess their risk for a future cardiac event. In patients with known or suspected coronary artery disease, a normal stress Cardiolite study is associated with a less than one percent chance that the patient will experience a hard cardiac event (death or myocardial infarction) in the next 12 months.
Bristol-Myers Squibb Medical Imaging, Inc., the makers of Cardiolite, has provided more than $2 million in a research grant to Yale University School of Medicine for the two-year study. The company also supplies product and technical support. Fujisawa Healthcare, Inc. also provides funding for the trial.
Cardiolite(R) (Kit for the Preparation of Technetium Tc99m Sestamibi for Injection) is the leading cardiac stress imaging agent in the United States. It is the only heart imaging agent that is FDA-approved to both non-invasively evaluate the heart’s pumping ability (function) and gauge the amount of blood flow to the heart muscle itself (perfusion) — and thus is used to quickly assess whether a patient has already had a heart attack or is at risk for one in the future. Cardiolite is also the only technetium agent in the U.S. approved for acquiring diagnostic information for use in patient management decisions. Cardiolite is a registered trademark of Bristol-Myers Squibb Medical Imaging, Inc