Stress imaging tests predict prognosis of heart disease in obese persons

Researchers identified an accurate method that may detect whether obese individuals have a low, intermediate or high risk of coronary artery disease, the leading cause of death in the United States, notes a report in a recent issue of the Journal of Nuclear Medicine.

"Stress myocardial perfusion imaging (or stress testing)-with better imaging quality made possible by using technetium-labeled agents-has apparently resulted in improved detection of coronary artery disease in obese patients," said Abdou Elhendy, an associate professor of medicine in the cardiology section at the Marshfield Clinic in Marshfield, Wis. "This can be helpful for physicians in planning management strategy," added the co-author of "Prognostic Stratification of Obese Patients by Stress 99mTc-Tetrofosmin Myocardial Perfusion Imaging."

Individuals with coronary artery disease have less blood flowing to the heart during stress because their arteries have become hardened and narrowed. This condition puts about 13 million Americans at risk every year for angina (chest pain), heart attack, heart failure and death.

About half a million Americans will die from coronary artery disease, "which may be silent particularly in patients with diminished physical activity," said Elhendy, who is also affiliated to the Thoraxcenter at the University Hospital Rotterdam in the Netherlands.

Currently, detecting the blockage of coronary arteries is based on an invasive procedure called coronary angiography. "Stress testing is proven useful in obese patients who have symptoms and/or other risk factors for coronary artery disease and can serve as a gatekeeper for that invasive and expensive procedure," Elhendy noted. "Stress myocardial perfusion imaging-with 99mTc-tetrofosmin-can effectively risk stratify obese patients and guide the selection of those who may require invasive intervention," he stated.

Heart problems can be easier to diagnose when the heart is working harder and beating faster than when it is at rest. During stress testing, an individual exercises (or is given a pharmacologic stress agent if unable to exercise) to make the heart work harder and beat faster while blood flow to the heart is being examined. The research team from the Netherlands used stress testing with exercise or a pharmacologic stress agent (dobutamine in conjunction with radiolabeled tetrofosmin, a widely available radiotracer) to assess perfusion (blood flow) to the heart muscle and determine risk of heart events in obese patients.