Visual Assessment Overestimates Lesion Severity vs. QCA

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Compared with quantitative coronary angiography (QCA), visual assessment by clinicians tends to overestimate lesion severity in patients undergoing percutaneous coronary intervention (PCI). The findings may present an opportunity for quality improvement, according to a paper published online March 7, 2013, ahead of print in Circulation.

For the Assessing Angiography (A2) project, Brahmajee K. Nallamothu, MD, MPH, of the University of Michigan (Ann Arbor, MI), and colleagues sought to capture contemporary practice patterns. They enlisted the participation of 7 US hospitals in 2011, randomly selecting 175 patients (n = 228 lesions) undergoing elective PCI. The researchers compared the clinical interpretation of angiography at the time of treatment with QCA results later obtained at a core lab using independent, blinded review.

Disagreement Between Visual Assessment, QCA

Details on visual assessment were reported for 216 lesions. The median percent diameter stenosis was 80%, with 213 lesions (98.6%) having at least 70% stenosis. Among them, 56 (26.3%) fell below that threshold on QCA. None were less than 50%.

QCA, performed in all 228 lesions, showed a median percent diameter stenosis of 74.6%. The mean difference in percent diameter stenosis between clinical interpretation and QCA was 8.2 ± 8.4%, reflecting greater lesion severity using visual assessment (P < 0.0001). The difference between the 2 tests varied across individual centers, ranging from 5.6% to 11.2%, but was consistent when excluding lesions associated with NSTEMI or within coronary artery bypass grafts.

Patients with the 3 lesions falling below 70% stenosis by clinical interpretation underwent documented stress test and/or fractional flow reserve (FFR) measurement. None of the lesions had less than 50% stenosis, while 56 (26.3%) fell between 50% and 70%. More than half of patients with intermediate lesions on QCA—the category of greatest disagreement between the 2 tests—had documented stress testing or FFR before PCI.

A Tool for Quality Improvement

Dr. Nallamothu told TCTMD in a telephone interview that while the angiography equipment used by some PCI centers possesses QCA capability, “in all honestly, it’s probably rarely applied online and in real time, [in part because] QCA itself still requires some user input.” In the future, computer-assisted techniques such as QCA may see wider use in clinical practice, he said. But even then they most likely will help facilitate diagnosis by serving as a “second reader” and should never be considered stand-alone tests.

Better visual assessment can come through quality improvement initiatives and also through interaction during daily practice, he noted.

“[Clinicians] can sometimes be in isolated silos. You get into your own practice and you’re doing cases, and there’s not really a lot of opportunity for feedback or review,” Dr. Nallamothu related. Such conversations may be more common at academic medical centers, he said, noting that cooperation among colleagues can sometimes lead to a center having a consistent approach to visual assessment.

QCA can be used in quality improvement initiatives as a way to look back and identify cases where visual assessment diverged from measurement of lesion severity by QCA, Dr. Nallamothu suggested. “The differences might be completely appropriate. It might be that visual assessment is able to evaluate the lesion much better than QCA in those settings because of complex anatomy,” he noted. In these “tough cases,” the operator can review his or her own work and share it with others, he said.

Dr. Nallamothu reported that this sort of initiative is currently in the planning stages and will be implemented at the centers that participated in the A2 program. “These places are already giving excellent care,” he said, adding that the aim is “to potentially raise that bar even further.”

QCA Does Not Rival Clinician’s Eye

In the current analysis, the investigators did not evaluate appropriateness, Dr. Nallamothu stressed. It is quite likely that all of the intermediate lesions on QCA were appropriately treated, he added, acknowledging that this requires further investigation.

“It’s definitely a gray area. [W]e’re not saying at all that QCA trumps visual assessment. In fact, at the end of the day I think it probably [goes the other] way,” Dr. Nallamothu concluded.

The true value may lie in looking at the gap between the 2 measurements and understanding how that might affect clinical decision making, he said. This is particularly relevant for intermediate lesions, where it might be useful “to have a threshold for using some other type of assessment, whether it’s incorporating more of the stress test data obtained before coronary angiography or FFR in the lab. Just having a stronger feeling about how to make that decision, because once a stent goes in, it doesn’t come out.”

 


Source:
Nallamothu BK, Spertus JA, Lansky AJ, et al. Comparison of clinical interpretation with visual assessment and quantitative coronary angiography in patients undergoing percutaneous coronary intervention in contemporary practice: The Assessing Angiography (A2) project. Circulation. 2013;Epub ahead of print.

 

 

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Disclosures
  • Dr. Nallamothu reports no relevant conflicts of interest.

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