Physicians may be ordering too many percutaneous coronary intervention (PCI) procedures by overestimating the degree of coronary stenosis in angiograms, according to a study from China published January 16 in JAMA Internal Medicine.
Researchers found that physician visual assessment (PVA) of stenosis didn't match up well with readings from an automated quantitative coronary angiography (QCA) software program. In fact, there was a discrepancy of 16 percentage points between the doctors' readings and the software's -- indicating that many patients are being sent on for interventional procedures who might be better treated with medical therapy and observation.
"We found that PVA significantly overestimated coronary stenosis severity compared with independent measurements by QCA, supporting the need for greater use of functional assessments prior to the performance of PCI," wrote the research team led by Dr. Haibo Zhang and Lin Mu from the Chinese Academy of Medical Sciences in Beijing (JAMA Intern Med, January 16, 2018).
Patients suspected of having coronary stenosis are typically converted to PCI procedures for revascularization based on physician visual assessment of stenosis on their diagnostic angiograms, usually if there is luminal narrowing of at least 70%. But such assessments can be prone to physician variability, especially compared with the use of automated software that is now being applied at research sites, the authors noted.
Zhang, Mu, and colleagues therefore decided to compare the degree of agreement between physician assessment and a commonly used quantitative coronary angiography software application (QAngio XA, Medis Medical Imaging Systems). Their patient population consisted of a subset of 1,295 individuals who participated in the Patient-Centered Evaluative Assessment of Cardiac Events (PEACE) study in China from 2012-2013.
The researchers split the study population into two groups: 689 patients without acute myocardial infarction (AMI) and 606 patients with AMI. In the patients without AMI, 97.8% had received percutaneous coronary intervention at the same time as their diagnostic angiography study. The researchers then calculated mean scores for the severity of luminal narrowing as graded by both the physicians and the software.
Compared with the automated software, the physicians tended to overcall the severity of stenosis for both groups of patients, the group found. The magnitude of the difference was greater among the patients without acute myocardial infarction.
| Visual assessment vs. software for coronary stenosis severity | ||||
| Patients without AMI | Patients with AMI | |||
| Physician visual assessment | QCA software | Physician visual assessment | QCA software | |
| Mean stenosis severity | 87.7% | 71.7% | 93.7% | 83.6% |
What's more, among the patients who did not have acute myocardial infarction and who were treated with PCI, almost half had lesions that the QCA software would not have graded as severe (greater than 70% narrowing) -- meaning they would not have been sent on to interventional therapy if the software were guiding treatment.
The researchers concluded by noting that the use of PCI procedures has increased dramatically in China over the past decade. While the government has made efforts to standardize the use of intervention, such as through training and quality control, it has made few efforts toward verifying that doctors are interpreting angiograms accurately.
The study could also have lessons for the U.S., they believe.
"Given that the clinical standard, PVA, frequently resulted in an overestimation of lesion severity compared with the less subjective QCA, it is possible that revascularization would not have been pursued in some lesions -- an implication that is similar to findings from the United States," they concluded.
These thoughts were echoed by an editorial that accompanied the study, penned by Dr. Rita Redberg, editor of JAMA Internal Medicine. Redberg believes that the inaccuracy of physician angiography interpretation is a "commonly known but little discussed" contributor to inappropriate revascularization.
"The best approach is not to refer these stable patients to the catheterization laboratory in the first place, but rather to start medical therapy and follow the patient clinically," Redberg concluded.
