Assessment of coronary physiology to guide revascularization decisions has been linked to lower adverse event rates than using angiography alone, but the adoption of techniques such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) continues to lag behind guideline recommendations.
Italian researchers conducted a nationwide study to see how closely their operators’ practices align with European and American recommendations for intracoronary pressure measurements, and to identify physicians’ reasoning for foregoing these strategies.
In an analysis of 1,858 cases across 76 Italian catheterization laboratories, Matteo Tebaldi, MD, and colleagues found that physiology-based guidance was used in accordance with guidelines about 48 percent of the time, and was used more often in patients with acute coronary syndromes.
“As might be expected, FFR and iFR assessment was used more often in intermediate lesions of the left anterior descending coronary artery to guide the decision to perform revascularization,” Tebaldi et al. wrote in JACC: Cardiovascular Interventions, which published their paper in conjunction with a presentation at EuroPCR 2018 in Paris. “However, it is important to note that nearly 20 percent of stenoses visually estimated to have DS (diameter stenosis) between 71 and 90 percent were not functionally significant when evaluated using FFR. This indicates that physiology-based guidance can be useful in assessing lesions deemed to be angiographically severe.”
The authors noted the most common reason for an operator to forego guideline-indicated physiological assessment was the confidence that clinical and angiographic data were enough to make the appropriate revascularization decision for the patient. This occurred in 39.3 percent of the cases, while guidewire-related concerns (11.1 percent) and preference for intracoronary imaging techniques (7.5 percent) were cited in fewer cases.
“Despite several studies that showed disagreement between physiology and visual estimation, most operators continue to consider angiography superior to physiology,” Tebaldi and colleagues wrote. “This is not necessarily driven by the operator’s desire to perform PCI, because approximately 50 percent of the lesions were not treated. Obviously, physiology assessment does not substitute for clinical judgment and should always be interpreted in the clinical context of each patient. However, a merely angiography-based approach results in a higher rate of discordant decisions with respect to the true functional importance of the stenosis and thus in unnecessary stenting or inappropriate deferral in approximately 30 to 50 percent of all cases.”
Operators who used visual assessment were found to be an average of four years older than those turning to invasive hemodynamic tests, suggesting younger physicians are more likely to seek decision-making help from those techniques.
“Educational programs focused on the advantages and disadvantages of invasive coronary physiology assessment should be implemented to fill the gap between guideline indications and daily practice,” the researchers wrote.
Time constraints, lack of reimbursement, adenosine costs and side effects have been hypothesized to be the primary drivers behind subpar uptake of coronary physiology assessments.
But this study and others prove the main obstacle is much simpler than that, according to the authors of an accompanying editorial.
Clinicians “think that we already know the answer,” wrote Nils P. Johnson, MD, MS, and Bon-Kwon Koo, MD, PhD.
“Although operators can be reluctant to admit it, the fundamental reason has received different labels: attitude, belief, local practice, ‘experience’ and culture. Put simply, we as a profession do not yet emotionally accept coronary physiology to guide treatment.”