Author + information
- Mai-Britt Vestergaard,
- Birgitte Krogsgaard Andersen,
- Jelmer Sybren Westra,
- Evald Høj Christiansen and
- Niels Ramsing Holm
Quantitative flow ratio (QFR) is a novel diagnostic modality enabling functional coronary lesion assessment by computation of invasive coronary angiography. QFR analysis in the prognostic proximal left anterior descending artery (LAD) is highly sensitive to observer decisions and optimal analysis is unknown.
The study was a pooled analysis of the WIFI-I (NCT02795585) and WIFI-II (NCT02264717) QFR studies. Cases with diffuse disease and lesions involving the proximal LAD were analyzed by three different analysis approaches for QFR and results were compared to fractional flow reserve (FFR). Methods were based on automatic reference function fitted to 1) the LAD, 2) the LMCA, or 3) a gender specific fixed reference size.
A total of 215 LAD lesions were analyzed in the two studies and 62 had diffuse disease involving the proximal LAD. After exclusion of cases with short non-visible left main coronary arteries, severe overlap, no nitro administration, 44 cases entered analysis. The differences between QFR and FFR were, 1) for QFR_LAD -0.03 (SD 0.10), for 2) QFR_LMCA 0.05(SD 0.11) and for 3) QFR_FIX 0.02 (SD 0.09). Diagnostic accuracy was determined by the receiver operator characteristics (ROC) curves (figure) and best fit was shown for QFR_FIX. Best combined fit achieved an AUC of 0.95 as the theoretic maximum. A modified algorithm for QFR analysis of proximal LAD based on gender specific fixed reference size is proposed and evaluated against the three evaluated methods and the best combined fit. The optimal QFR analysis algorithm and dual observer results are presented at CRT.
QFR is a very promising tool for wire-free in-procedure physiological lesion assessment but evaluation of proximal LAD lesions is strongly influenced by the analysis approach. An optimized, evidence based analysis algorithm is presented.