SPECT Identifies Benefits of PCI Over Drug Therapy
November 4, 2007 – 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 late-breaking clinical trial results presented at the American Heart Association’s Scientific Sessions 2007.
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 substudy 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 years. In this substudy of the original trial, researchers used SPECT imaging to look at the hearts of 313 of those patients. The imaging was done on two groups of patients prior to and after they had undergone treatment for coronary artery disease. One group received optimal medical therapy along with angioplasty; the other group received optimal medical therapy (OMT) alone.
Researchers found 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 OMT.
“Our outcomes in this substudy don’t change the main COURAGE trial results,” said Leslee J. Shaw, Ph.D., principal investigator of the nuclear substudy and a professor of medicine at Emory University in Atlanta, Ga. “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 ischemia resolution.”
At baseline, the 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; 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.
Support for this study was provided by Bristol Myers-Squibb Medical Imaging and Astellas Healthcare.
Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.
For more information: www.americanheart.org