ACIST-FFR Study (Assessment of Catheter-Based Interrogation and Standard Techniques for Fractional Flow Reserve Measurement)

Abstract

Background: Measurement of fractional flow reserve (FFR) to guide coronary revascularization lags despite robust supportive data, partly because of the handling characteristics of traditional coronary pressure wires. An optical pressure-monitoring microcatheter, which can be advanced over a traditional coronary guidewire, facilitates FFR assessment but may underestimate pressure wire-derived FFR.

Methods and results: In this prospective, multicenter trial, 169 patients underwent FFR assessment with a pressure wire alone and with a pressure microcatheter over the pressure wire. An independent core laboratory performed quantitative coronary angiography and evaluated all pressure tracings. The primary end point was the bias or difference between the microcatheter FFR and the pressure wire FFR, as assessed by Bland-Altman analysis. The mean difference between the microcatheter and the pressure wire-derived FFR values was -0.022 (95% confidence interval, -0.029 to -0.015). On multivariable analysis, reference vessel diameter (P=0.027) and lesion length (P=0.044) were independent predictors of bias between the 2 FFR measurements. When the microcatheter FFR was added to this model, it was the only independent predictor of bias (P<0.001). The mean FFR value from the microcatheter was significantly lower than from the pressure wire (0.81 versus 0.83; P<0.001). In 3% of cases (95% confidence interval, 1.3%-6.7%), there was clinically meaningful diagnostic discordance, with the FFR from the pressure wire >0.80 and that from the microcatheter <0.75. These findings were similar when including all 210 patients with site-reported paired FFR data.

Conclusions: An optical, pressure-monitoring microcatheter measures lower FFR compared with a pressure wire, but the diagnostic impact appears to be minimal in most cases.

Clinical trial registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02577484.

Keywords: confidence intervals; coronary angiography; coronary artery disease; fractional flow reserve; heart.

© 2017 The Authors.

Figures

Figure 1.

Flowchart depicting patients included and excluded in the study. FFR indicates fractional flow reserve.

Figure 2.

Correlation between the microcatheter and pressure wire fractional flow reserve (FFR) measurements.

Figure 3.

Bland–Altman plot comparing fractional flow reserve (FFR) measurements from the microcatheter to those from the pressure wire.

Figure 4.

Bland–Altman plot comparing fractional flow reserve (FFR) measurements from the pressure wire with and without the microcatheter on top of the wire.

Figure 5.

The slope and intercept (and 95% CI [confidence interval]) of the Passing–Bablok regression between paired fractional flow reserve (FFR) measurements by the microcatheter and pressure wire.

Figure 6.

Receiver operator characteristic curve comparing fractional flow reserve (FFR) measurement with the microcatheter to FFR measurement with the pressure wire. AUC indicates area under the curve.