Evaluation of the Fractional Flow Reserve by Computer Tomography Data: Comparison of the Calculated Parameters with the Results of Invasive Measurements.

Aim      To create a three-dimensional mathematical model of coronary flow in patients with ischemic heart disease based on findings of computed tomography angiography (CTA) with subsequent calculation of the fractional flow reserve (FFRCTA) and comparison of estimated FFRCTA with FFR reference values measured by coronary angiography (CAG).Material and methods  The study included 10 patients with borderline stenosis (50-75 %) as determined by CTA performed with a 640­slice CT-scanner. Based on CTA findings, three-dimensional mathematical models were constructed for further calculation of FFRCTA. Later, an invasive measurement of FFR (FFRINV) was performed for all patients. FFR values <0.8 indicated the hemodynamic significance of stenosis.Results FFRCTA and FFRINV values differed insignificantly in most cases (n=9) and exceeded 5% in only one case. The regression analysis showed a close correlation between estimated and invasively measured FFR values.Conclusion      Preliminary results showed a good consistency of calculated and measured FFR values. Therefore, further development of the method for mathematical modeling of three-dimensional blood flow by CTA findings is promising. Noninvasive evaluation of FFR is particularly relevant for analysis of hemodynamic significance of borderline (50-75 %) coronary stenoses.

Correlations between clinical and laboratory findings and prognostically unfavorable CMR-based characteristics of acute ST-elevation myocardial infarction.

Aim To evaluate factors associated with unfavorable predictive characteristics of ST-segment elevation acute myocardial infarction (STEMI) as per data of magnetic resonance imaging (MRI).Material and methods The study included 52 patients with STEMI who underwent a primary percutaneous coronary intervention (pPCI). Contrast-enhanced cardiac MRI was performed for all patients on days 3-7. Delayed contrast-enhancement images were used for assessing infarct size, presence of microvascular obstruction (MVO) areas, and heterogeneity zones.Results Multifactorial analysis showed that independent predictors of MVO were type 2 diabetes mellitus (DM) (relative risk (RR) 1.9, confidence interval (CI): 1.1-3.26, р=0.012), increased levels of brain natriuretic peptide (BNP) (RR 2.04, CI: 1.39-2.99, р=0.004) and creatine kinase (CK) (RR 2.06, CI: 0.52-0.80, р=0.02), and infarct size (IS) (RR 2.81; CI: 1.38-5.72, р=0.0004). Construction of ROC curves provided the quantitative values of study indexes, at which the risk of MVO increased. For BNP, this value was ≥276 pg/ml (sensitivity, 95.7 %; specificity, 37.9 %); for CK ≥160 U/l (sensitivity, 74.1 %; specificity, 61.9 %); and for IS ≥18.8 % (sensitivity, 79.3 %; specificity, 69.6 %). Correlation analysis of risk factors for increased size of the heterogeneity zone showed significant correlations of the heterogeneity zone size with older age of patients (r=0.544, р<0.0001), higher concentrations of BNP (r=0.612, р<0.0001), CK (r=0.3, 95 % CI: 0.02-0.5, р=0.03), and C-reactive protein (CRP) (r=0.59, CI: 0.3-0.7, р=0.0001). Increased levels of CK (r=0.53, 95 % CI: 0.29-0.70, р=0.0001) and BNP (r=0.55, 95 % CI: 0.28-0.70, p=0.0003) significantly correlated with increased IS.Conclusion Risk of MVO formation as per MRI data increased in the presence of type 2 DM and IS ≥18.8 % (р<0.05). Formation of MVO in patients with STEMI was associated with increased levels of BNP ≥276 pg/ml and CK ≥160 U/l (р<0.05). Increased levels of BNP, CK, and CRP were associated with a larger size of heterogeneity zone according to data of the correlation analysis. A larger heterogeneity zone was more typical for older patients. Increased levels of CK and BNP were also associated with larger IS. The correlation analysis did not show any significant interactions between the size of heterogeneity zone, IS, and MVO size (р>0.05).