Assessment of intermediate coronary lesions by fractional flow reserve and quantitative flow ratio in patients with small‐vessel disease

Abstract

Background: Quantitative flow ratio (QFR) has recently been introduced as a novel, less-invasive, adenosine-free measure for functional coronary lesion assessment. Whether reference vessel dimensions affect functional lesion assessment is uncertain. Methods: A total of 436 patients with 516 interrogated coronary vessels by means of FFR were included in the study. Patients were dichotomized according to the median reference vessel diameter (group 1: ≤2.8 mm and group 2: >2.8 mm). QFR analyses were performed offline at the institution's core laboratories. Results: Reference vessel diameter was 2.5 [2.3-2.7] mm in group 1 and 3.3 [3.0-3.6] mm in group 2. Diameter stenosis (41.4 [36.4-47.6] % vs. 41.4 [36.4-45.7] %, p = .20) did not differ among groups. Median FFR values were lower in group 1 (0.87 [0.81-0.92]) as compared with group 2 (0.89 [0.84-0.93], p = .001). Consistently, QFR values were lower in group 1 (0.88 [0.82-0.92]) than in group 2 (0.91 [0.85-0.94], p = .001). The proportions of functionally significant coronary lesions as defined by FFR ≤0.80 were 24.1% and 14.2% in groups 1 and 2 (p = .005), and as defined by cQFR ≤0.80 20.4% and 11.8% (p = 0.009), respectively. In ROC analysis for an FFR ≤.80, the AUC was 0.89 (95% CI 0.85-0.93, p < .001) in group 1 and 0.81 (95% CI 0.76-0.86, p < .001) in group 2. Conclusions: These results suggest that QFR measurements are accurate irrespective of the reference vessel diameter. Future studies are needed to elucidate the higher percentage of functionally significant lesions observed in small vessels despite a similar angiographic lesion severity.

Small vessel coronary artery disease: How small can we go with myocardial revascularization?

“…Recently, a new quantitative flow ratio (QFR) method of functional evaluation of coronary arteries was introduced, which is based on wire-free and adenosine-independent analysis of coronary angiography [27]. This promising new diagnostic tool was demonstrated to be as effective in vessels with diameter of 2.3-2.7 mm as in larger arteries with diameter 3.0-3.6 mm [28]. Similar technology based on non-invasive fractional flow reserve derived from computed tomography (FFRCT) has been introduced, but no data regarding its accuracy depending on vessel diameter have been published [29].…”

Comparing QFR and FFR in small vessels—Expanding the spectrum of use

“…Vessel size is usually correlated to volume of subtended myocardium such that for a fixed angiographic %DS, one might expect larger vessels to have a lower FFR, as was shown for left anterior descending coronary artery lesions 3 . Interestingly, this relationship was not seen in this study, 2 where the smaller vessels tended to have a lower FFR and QFR.…”

“…In this issue of Catheterization and Cardiovascular Interventions , Erbay et al 2 analyze the accuracy of QFR for estimating FFR in intermediate coronary lesions in patients with small diameter vessels. FFR and QFR (offline analysis in a core lab) were measured in 436 patients divided by reference vessel diameter (group 1: ≤2.8 mm with a mean of 2.5 [2.3–2.7] mm; and group 2: >2.8 mm with a mean of 3.3 [3.0–3.6] mm).…”

“…The larger, multicenter SYNTAX II analysis 1 found that although the diagnostic performance of QFR to predict binary wire‐based FFR ischemia was substantial (AUC: 0.81, accuracy: 73.8%), diagnostic discordance was more likely to occur in side‐branch lesions, involvement of a bifurcation or trifurcation, small vessels, and microvascular function 4 . Erbay et al 2 argue that the higher incidence of multivessel coronary artery disease in the SYNTAX trial may have contributed to the different results, but this is speculative. A more likely reason is that a different definition of small vessels was used (<2.8 mm in this study and <2.25 mm in the SYNTAX trial).…”

QFR Predicts the Incidence of Long-Term Adverse Events in Patients with Suspected CAD: Feasibility and Reproducibility of the Method

“…Increasing evidence supports its applicability in different conditions. In fact, its usefulness has been demonstrated not only in the context of native coronary artery stenosis, including small vessel disease [15], but also in particular lesion settings, such as in-stent restenosis [16]. Moreover, its use can be applied immediately after PCI, in order to confirm the hemodynamic results of the revascularization and eventually to guide further treatment, as recently demonstrated in the HAWKEYE study [17].…”