Effect of Guiding Catheter Extubation During Physiological Assesment of Stenosis.

BACKGROUND

Extubation of the coronary guiding catheter may affect flow and pressure measurements in the coronary vessel during invasive coronary angiography (ICA).

AIM

This study aims to investigate the impact of guiding catheter extubation on fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR).

METHODS

This predefined subgroup analysis of the Dan-NICAD 2 study included patients with chronic coronary syndrome referred to ICA based on a coronary computed tomography angiography. Thermodilution was performed in all vessels evaluated with 30%-90% diameter stenosis on a visual estimate. The primary endpoints were FFR, CFR, and IMR changes when the guiding catheter was extubated from the coronary ostium. Three-dimensional quantitative coronary angiography analysis was conducted to evaluate whether the proximal flow area, defined as the area of the guiding catheter subtracted from the area of the vessel ostium, correlated with the changes in FFR, CFR, and IMR.

RESULTS

In 84 patients, coronary physiological measurements were performed twice: once with the guiding catheter intubated and once extubated. FFR decreased during guiding catheter extubation (0.82 ± 0.09 vs. 0.80 ± 0.10) with a mean difference of 0.02, 95% CI [0.01-0.03], p < 0.001. Following extubation, eight patients (8.7%) showed FFR values shifting from > 0.80 to ≤ 0.80. IMR increased during guiding catheter extubation (16.8 ± 8.50 vs. 21.4 ± 16.1) with mean difference of 4.67 [95% CI 1.74-7.60], p = 0.002. No significant changes in CFR were observed; intubated 3.09 ± 1.31 vs 2.84 ± 1.30; difference mean 0.25, [95% CI -0.07 to 0.56], p = 0.12. No significant correlations were found between the proximal flow area and the difference in FFR, CFR, and IMR from intubated to extubated: (r -0.14, p = 0.23), (r -0.11, p = 0.34), and (r -0.16, p = 0.17), respectively.

CONCLUSION

Extubating the guiding catheter decreased FFR and increased IMR. This resulted in an FFR decrease from > 0.80 to ≤ 0.80 in 8.7% of patients. CFR remained unchanged. No significant correlation was found between FFR/IMR changes and proximal flow area.