Single photon emission computed tomography (SPECT) can identify which patients will benefit more from undergoing percutaneous coronary intervention (PCI) than receiving medical therapy alone for blocked coronary arteries, according to Leslee J. Shaw, PhD, professor of medicine at Emory University School of Medicine and principal investigator of the nuclear sub-study.
Dr. Shaw presented late breaking clinical trial results at the American Heart Association's 2007 Scientific Sessions conference.
Myocardial perfusion SPECT (MPS) is a nuclear imaging technique that assesses blood flow in the heart by taking a series of pictures around the chest after injecting a radioactive tracer into the blood. In a nuclear sub-study of the Clinical Outcomes Using Revascularization and Aggressive Drug Evaluation (COURAGE) Trial, researchers found that MPS imaging could help single out those patients more likely to benefit from PCI, or angioplasty.
The COURAGE trial (conducted between 1999 and 2004) enrolled and studied 2,287 patients at 50 U.S. and Canadian centers comparing clinical outcomes over a follow-up period ranging from 2.5 to 7.0 years. There were no differences in rates of deaths, heart attack, stroke or hospitalization for acute coronary syndromes between the patients who underwent PCI and those who only received optimal medical therapy (OMT).
"Our substudy outcomes don't change the main trial results," says Leslee J. Shaw, PhD, principal investigator of the nuclear substudy and a professor of medicine at Emory University. "It does clarify care for a certain subset of stable chest pain patients who have stress induced ischemia prior to treatment. This group of patients benefited from PCI and had a greater reduction in ischemia by one year. The main effect this could have on clinical practice is that patients with ischemia may be more often referred to PCI for the purpose of ischemia resolution."
Researchers used SPECT imaging to look at the hearts of two groups of patients who underwent treatment for coronary artery disease. One group received optimal medical therapy along with angioplasty; the other group received optimal medical therapy alone.
At baseline, the patient groups were similar, including anginal class, level of ischemia and the number of patients who had multiple diseased vessels. At follow-up imaging, treatment reduced ischemia by 2.7 percent in patients who received PCI with OMT, whereas OMT only patients had just a 0.5 percent reduction.
The SPECT images also showed that some patients had a very significant recovery of heart muscle (more than 5 percent) -- 33 percent of patients with PCI and OMT showed a reduction in ischemia of 5 percent or more, compared with 19 percent of OMT only patients. Among the patients who had reduced ichemia, nearly 80 percent of both treatment groups were free of angina. However, in patients who began the study with high-risk ischemia (those with greater than 10 percent of their heart muscle compromised), treatment with PCI and OMT was more commonly effective in reducing ischemia than OMT alone.