Noninvasive approach provides better "image"

USA Today (Society for the Advancement of Education), Oct, 2007

Physicians need to know how badly heart vessels are blocked before they can decide how to treat patients at risk of having a heart attack. One standard approach to "imaging" suspected blockages involves injecting a radioactive substance with a very short half-life into the bloodstream. The patient subsequently undergoes an exercise stress test, and the radioactive material is tracked as it travels through the cardiovascular system, identifying narrowing or blockage. That process is called single photon emission computed tomography, or SPECT.

A study by Michael E. Merhige, clinical associate professor of nuclear medicine at the University at Buffalo (N.Y.) and medical director of The Heart Center at the Niagara Falls Memorial Medical Center, shows that a newer method, called positron emission tomography myocardial perfusion imaging, or PET MPI, provides a more accurate "picture" of coronary obstruction, costs 30% less, reduces the need for follow-up invasive procedures by 50%, and produces excellent clinical outcomes.

"Our evidence has shown that invasive procedures such as coronary arteriography [inserting a cardiac catheter into an artery in the upper arm or thigh, threading it through the vessel and injecting a contrast medium directly into the heart], bypass surgery, and stent placement are overused in the United States," asserts Merhige. "Using these procedures when noninvasive approaches work equally well, if not better, contributes to unnecessary health care expenses without improved patient outcomes."

The actual costs of these two procedures are quite similar, Merhige indicates, but the accuracy of PET MPI eliminated the need for additional coronary artery bypass grafting procedures in more than half of the participants. He also notes that SPECT MPI is less accurate than PET MPI in women and overweight patients.

"This study supports the idea that the future of cardiology lies in noninvasive imaging, combined with aggressive use of cholesterol-lowering drugs and lifestyle changes, such as better nutrition, regular exercise, and smoking cessation," Merhige concludes.