What is the clinical evidence from this study?

Study design: Observational. Population: Angina and acute myocardial infarction (AMI) (n=915). Intervention: Quantitative flow ratio (QFR) vs. Fractional flow reserve (FFR). Primary outcome: Diagnostic accuracy of QFR ≤ 0.8 for identifying FFR ≤ 0.8 (Accuracy 95.54%, 95% CI 94.13 to 96.70%).

February 4, 2021Open Access

Influence of lesion and disease subsets on the diagnostic performance of the quantitative flow ratio in real-world patients

KLKwan Yong LeeSt. Mary's Hospital BHByung‐Hee HwangSt. Mary's Hospital MKMoo Jun KimSoonchunhyang University

Key Result

Quantitative flow ratio demonstrated a high overall diagnostic accuracy of 95.54% for identifying fractional flow reserve ≤ 0.8 in real-world patients with angina and acute myocardial infarction.

Study Design

Type

Observational (n=915)

Blinding

Blinded analysis

Multicenter

Yes

Structured PICO

Does quantitative flow ratio (QFR) accurately identify functional ischemia compared to fractional flow ratio (FFR) in patients with angina and acute myocardial infarction?

Population

915 patients (assessing 1077 vessels) with angina and acute myocardial infarction (AMI) undergoing fractional flow ratio (FFR) evaluation

Intervention

Quantitative flow ratio (QFR)

Comparator

Fractional flow ratio (FFR) evaluation (reference standard FFR ≤ 0.8)

Outcome

Diagnostic accuracy of QFR for identifying an FFR ≤ 0.8surrogate

QFR demonstrates high overall diagnostic accuracy for assessing functional ischemia, though performance is significantly reduced in borderline FFR zones and tandem lesions, particularly in patients with AMI.

Main Result

Effect estimate: Accuracy 95.54% (95% CI 94.13 to 96.70%)

Limitations

A large proportion of the vessels were assessed to have mild (PAS < 50%) or severe (PAS > 70%) stenosis, which may have increased the overall diagnostic accuracy.
The analysis was performed with only 2 physicians, which could not ensure that there was no interobserver variation.
Further evidence with a large study is needed to investigate the role of QFR in specific subgroups of patients with microcirculatory disease, arrhythmias, culprit lesions with AMI, and other complicated lesions.

Abstract

The quantitative flow ratio (QFR) is a novel angiography-based computational method assessing functional ischemia caused by coronary stenosis. This study aimed to evaluate the diagnostic performance of quantitative flow ratio (QFR) in patients with angina and acute myocardial infarction (AMI) and to identify the conditions with low diagnostic performance. We assessed the QFR for 1077 vessels under fractional flow ratio (FFR) evaluation in 915 patients with angina and AMI. The diagnostic accuracies of the QFR for identifying an FFR ≤ 0.8 were 95.98% (95% confidence interval CI 94.52 to 97.14%) for the angina group and 92.42% (95% CI 86.51 to 96.31%) for the AMI group. The diagnostic accuracy of the QFR in the borderline FFR zones (> 0.75, ≤ 0.85) (91.23% 95% CI 88.25 to 93.66%) was significantly lower than that in others (difference: 4.32; p = 0.001). The condition accompanying both AMI and the borderline FFR zone showed the lowest QFR diagnostic accuracy in our data (83.93% 95% CI 71.67 to 92.38). The diagnostic accuracy was reduced for tandem lesions (p = 0.04, not correcting for multiple testing). Our study found that the QFR method yielded a high overall diagnostic performance in real-world patients. However, low diagnostic accuracy has been observed in borderline FFR zones with AMI, and the hybrid FFR approach needs to be considered.

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