Discordance between fractional flow reserve and nonhyperemic index with a fiber-optic pressure wire. READI EPIC-14

Functional assessment of coronary stenosis severity with the piezo-electric sensor pressure wire has shown a discrepancy of up to 20% between hyperemic and nonhyperemic indexes. No data are available with fiber-optic pressure wires. The aim of this study was to evaluate the incidence and factors related to the diagnostic discordance between these indexes with a fiber-optic pressure wire. Secondary aims were to assess diagnostic reproducibility in 2 consecutive measurements of fractional flow reserve (FFR) and diastolic pressure ratio (dPR) and evaluate the drift rate.

We conducted a prospective, observational multicenter study in patients undergoing functional assessment with a fiber-optic pressure wire. We took 2 consecutive measurements of the dPR (cutoff point 0.89) and FFR (cut-off point 0.80) in each lesion analyzed. The diagnostic correlation between 2 measurements with the same technique and between the 2 techniques (dPR and FFR) was assessed. Clinical and angiographic factors associated with discordance (FFR-/dPR+ and FFR+/dPR-) between the 2 techniques were analyzed.

We included 428 cases of stenosis (361 patients). Diagnostic reproducibility was 95.8% for the dPR, with a correlation coefficient between the 2 measurements (dPR1 and dPR2) of 0.974 (P < .0001). For FFR, the diagnostic reproducibility was 94.9% with a correlation coefficient (FFR1 and FFR2) of 0.942 (P < .0001). The diagnostic discordance was 18.2% (FFR+/dPR- 8.2% and FFR-/dPR+ 10%). Among the variables analyzed, the factors significantly associated with FFR-/dPR+ discordance in the multivariate analysis were hypertension and intracoronary adenosine. The only factors significantly associated with FFR+/dPR- discordance were age < 75 years and stenosis > 60%. The drift rate was 5.7%.

Although FFR and dPR measurements with a fiber-optic pressure wire have excellent reproducibility and a low drift rate, the discordance rate remains similar to those in previous studies with a piezo-electric pressure wire. FFR-/dPR+ discordance is associated with intracoronary adenosine and hypertension. FFR+/dPR- discordance is related to age < 75 years old and stenosis > 60%.