Noninvasive assessment of the fractional reserve of coronary blood flow with a one-dimensional mathematical model. Preliminary results of the pilot study

Aim. To evaluate the diagnostic accuracy of a noninvasive method of fractional flow reserve (FFR) assessment based on a one-dimensional hemodynamic model build on data obtained from the coronary computed tomography angiography (CCTA).

Material and methods. The study enrolled 57 patients: 16 of them underwent 64-slice computed tomography — included retrospectively, 34 — prospectively, with a 640-slice CT scan. Specialists from the Laboratory of Mathematical Modeling processed CT images and evaluated noninvasive FFR. Ischemia was confirmed if FFR <0,80 and disproved if FFR ≥0,80. After that the prospective group of patients was hospitalized for invasive FFR assessment as a reference standard; if ischemia was proved, patients underwent stent implantation. In the retrospective group, patients already had invasive FFR values estimated. Statistical analysis was performed using R programming language packages (cran-r.project.com). Continuous variables are presented as mean values ± standard deviations, order variables are presented as medians with interquartile ranges in parentheses. We used the D’Agostino-Pearson omnibus test for the assessment of normality of distribution; a Q-Q Plot was also constructed. We performed the Bland-Altman analysis and ROC-analysis for comparison of these two methods, and the Pearson’s chi-squared to assess the degree of correlation.

Results. During data processing, 3 patients of the retrospective and 34 patients of the prospective group were excluded from the study. The sensitivity of our method was 90,91% (95% CI; 58,72-99,77), specificity — 86,67% (95% CI; 59,54-98,34), P<0,05, accuracy — 88,46 (95% CI; 69,85-97,55) — in per-vessel analysis. In perpatient analysis, the sensitivity was 91,67% (95% CI; 61,52-99,79), specificity — 80% (95% CI; 28,36-99,49), (P<0,05); accuracy 88,24 (95% CI; 63,56-98,54).

Conclusion. Our method has quite a high accuracy and can be successfully used in clinical practice in order to enhance the diagnostic efficiency of the CCTA.

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