Fewer than half of Medicare patients undergoing elective percutaneous coronary intervention for stable angina had a stress test to document ischemia, according to cohort study of more than 20,000 individuals.
“Without documentation of ischemia, PCIs may have been performed in patients who would not have benefited from the procedure,” Dr. Grace A. Lin of the University of California, San Francisco, and her associates reported.
Guidelines published jointly by the American College of Cardiology, the American Heart Association, and the Society for Cardiovascular Angiography and Intervention state that in patients with stable angina any vessels to be dilated via PCI must be “associated with a moderate to severe degree of ischemia on noninvasive testing.”
Dr. Lin and her colleagues assessed the frequency of stress testing in a cohort of 23,887 Medicare patients treated throughout the United States in 2004.
Overall, only 45% of the patients underwent stress testing within 90 days prior to their elective PCI.
This proportion varied dramatically by geographic region, from 22% in some areas to 71% in others. It was unclear why such variation exists, since stress testing is widely available and there was no correlation with the volume of PCIs done in those geographic regions. This finding shows that “local practice patterns may supersede clinical guidelines and evidence from clinical trials in the decision-making process for patients with stable CAD,” the investigators said (JAMA 2008;300:1765–73).
Younger physicians and those who performed higher volumes of PCIs were less likely than were others to perform stress testing. “This suggests that physician decision making regarding PCI was influenced less by the presence of ischemia, as guidelines suggest, and more by physicians' own biases and community practice patterns,” Dr. Lin and her associates said.
Similarly, certain patient characteristics predicted the use of a stress test. Patients who had previously undergone cardiac catheterization, older patients, and those with comorbidities such as rheumatic or pulmonary disease were less likely to have stress tests. “Although these factors do increase the probability that obstructive CAD is present, evidence of ischemia (not just visualization of anatomy) is crucial in determining if the use of PCI is appropriate,” the researchers noted.
In an editorial comment accompanying this report, Dr. George A. Diamond and Dr. Sanjay Kaul of Cedars-Sinai Medical Center, Los Angeles, said “the analyses that were performed leave the clear impression that referral for PCI was influenced less by objective evidence of ischemia than by incidental factors” (JAMA 2008;300:1817–9).