In China, doctors are overestimating the severity of coronary stenosis — the abnormal narrowing of blood vessels in the heart and a hallmark of coronary artery disease — say researchers from Yale and China. These findings have been published in the Jan. 16 edition of JAMA Internal Medicine.
In patients with coronary artery disease, the leading cause of death worldwide, doctors must perform coronary angiography to determine the severity of stenosis. The technique known as physician visual assessment (PVA) has long been the medical standard for measuring the degree of stenosis in order to determine the need for revascularization — often through percutaneous coronary intervention (PCI), which uses a balloon catheter to clear a narrowed or obstructed artery. However, there is another less used and possibly more accurate technique for measuring the degree of stenosis: quantitative coronary angiography (QCA), a highly reproducible computer-assisted technique.
“Although PVA of stenosis severity is a standard clinical practice, there are concerns about its accuracy,” said Lin Mu, co-first author on the paper and M.D. candidate at Yale School of Medicine. “Our objective in this study of patients undergoing PCI in China was to compare PVA with QCA as a means of assessing stenosis severity before the procedure. We wanted to expand on the findings of a 2013 U.S. study, which identified marked differences in stenosis severity based on whether it was measured by QCA or estimated by PVA.”
This Yale-led study built on the 2013 study in the United States and tested a larger and more diverse sample of patients from China who were undergoing PCI, whether or not they had had an acute myocardial infarction (AMI, a heart attack). After comparing the results of PVA and QCA in 1,295 adults with and without AMI, the researchers found that the diameter of the blood vessel with stenosis as estimated by PVA was 16% greater than the measurements by QCA in patients without AMI, and 10.2% greater in those with AMI. In other words, said the researchers, the more subjective method (PVA) was indicating more severe stenosis than the more objective method (QCA) was — just as was found in the United States.
The researchers note that even though the efficacy of PVA was challenged as long as 40 years ago, due to its convenience, efficiency, and ease of implementation, visual assessment is still the main method clinicians use to determine percent diameter stenosis in China and many other countries, including the U.S. Given that PVA frequently resulted in an overestimate of the severity of stenosis compared with the less-subjective QCA, it is possible clinicians would not have pursued revascularization in some cases had they been measured with only QCA instead, said the researchers.
“Our findings are particularly important in China, where functional assessments are rarely used and decisions about interventions rely heavily on PVA,” said Harlan Krumholz, senior author on the study and cardiologist at Yale Medicine. “Also, from a practical standpoint, PCI resources are limited relative to the rapid growth of cardiovascular needs in China, so procedures like PCI should be concentrated on the patients in which they are most needed — in this case, those who have stenosis that is sufficiently medically severe and fit into a category where benefit has been demonstrated. We need to develop strategies to improve the information about the coronary anatomy.”
There are limitations to QCA as well, such as its challenges in assessing complex lesions, note the researchers, but they pointed out that group readings of the angiograph can increase accuracy in more complex situations. Additionally, said the researchers, doctors could learn from the quantitative logic of QCA and apply it in their “real-time” practice as well by taking steps such as standardizing the calibration process using specific catheters or receiving feedback on their estimates of stenosis severity to help them calibrate their own interpretations of the angiograph.
“Additional study will be required to find out exactly how we should update our clinical standards for the measurement of stenosis severity,” said Krumholz. “But what is clear already is that when one half of the lesions that undergo PCI in China may not be clinically severe enough to warrant it, we need to improve — just as we do in the United States.”
Other study authors include Haibo Zhang, Shuang Hu, Brahmajee K. Nallamothu, Alexandra J. Lansky, Bo Xu, Georgios Bouras, David J. Cohen, John A. Spertus, Frederick A. Masoudi, Jeptha P. Curtis, Runlin Gao, Junbo Ge, Yuejin Yang, Jing Li, Xi Li, Xin Zheng, Yetong Li, and Lixin Jiang.
This study was supported by funding from the Research Special Fund for Public Welfare Industry of Health from the National Health and Family Planning Commission of China, the National Key Technology R&D Program from the Ministry of Science and Technology of China, and the 111 Project.