Study Examines Possible Overuse of Invasive Cardiac Treatments

December 15, 2008 - In regions of the country where cardiologists perform high numbers of cardiac catheterizations to diagnose heart problems, patients may be receiving percutaneous cardiac interventions (PCI) more than they need or want, according to a study published online last week in the journal Circulation.
In the study, funded by the Foundation for Informed Medical Decision Making headquartered in Boston, Maine Medical Center researchers analyzed the relationship between cardiac catheterizations and the two most common invasive cardiac treatments used to restore blood flow — PCI and coronary artery bypass graft (CABG) surgery. They found a very high correlation between cardiac catheterization rates and PCI rates; researchers noted a much weaker connection between cardiac catheterization and the number of CABGs.
"Several recent studies on managing heart disease have touted the benefits of treatment with medication and lifestyle changes — as opposed to invasive treatment,” said Lee Lucas, Ph.D., principal investigator at the Maine Medical Center Research Institute. "The results from our study reflect what might be a tendency for physicians to opt for treating invasively rather than conservatively if they see anything unusual during the diagnostic process."
"Our research indicates that patients may be getting PCIs that aren't necessary," said Lucas. She says that her findings might reflect the fact that criteria for PCIs are not as clearly defined as those for CABG.
"In addition, performing the diagnostic test and treatment in the same procedure, which is common practice, results in a situation in which patients have little opportunity to share in the decision making process before a PCI is performed." The concern, Lucas notes, is that catheterizations and PCIs are often done during a single procedure, where there is little opportunity for doctors to review results of the catheterization.
In a cardiac catheterization, a physician threads a catheter through an artery in the groin into the heart to evaluate that organ and surrounding blood vessels. If the test reveals a lesion, the physician will perform a PCI. This involves keeping the catheter in place after the diagnosis, inserting a tiny balloon to compress the narrow area in a blood vessel, and then inserting a small stent to permanently hold the vessel open. If blockage is severe enough to require CABG, the physician removes the catheter and sends the patient to surgery where a piece of artery is used to bypass the blocked areas.
To obtain their findings, the research team reviewed a 20 percent sample of Medicare part B claims nationwide and calculated the rates of testing and treatment by region of the country, adjusting for regional demographic differences.
They found that cardiac catheterization rates varied substantially across regions, ranging from 16 per thousand in some regions to 77 per thousand in others. And, they saw a strong correlation of cardiac catheterization rates to total treatments (R2 = 0.84). However, they also discovered a much weaker correlation between the tests and CABG rates (R2 = 0.41) with the suggestion of a threshold, beyond which further testing did not result in additional surgeries. On the other hand the correlation between cardiac catheterization testing rates and PCI rates was very strong (R2 = 0.78) and linear, meaning the more tests conducted, the greater the numbers of PCIs performed.
The Northeast region, including Maine Medical Center, has some of the lowest cardiac catheterization rates in the country. These low rates indicate conservative treatment and the likelihood that PCIs done here are more likely to be done appropriately.
Lucas and her team believe this study sheds light on the real challenges that now face the medical community in the management of heart disease — the need for developing clearer criteria for performing these procedures, which are not without risks and the importance of taking the individual patient's preferences into account.
In their paper, the researchers cite a Canadian study that demonstrated that if patients used a decision-making aid before PCI, they would opt out of treatment 28 percent more frequently than for treatment. Another study also suggested that physicians often performed PCIs, even when not supported by evidence did not support, to avoid a feeling of "regret" and because of a belief that opening an artery can only be beneficial to a patient even if the blockage was unrelated to symptoms.
"Most older people will eventually show some signs of cardiac lesions during catheterization testing," said Lucas. "What we need to ask ourselves is 'Should we be testing more people?' And, once tested, should we treat every lesion, even if the individual's symptoms and quality of life are not likely to be impacted?"
In the future, Lucas and her team plan to assess the impact of randomized trials that indicated that PCI may be overused.
Source: Maine Medical Center
For more information: www.mmc.org