One-Dimensional Mathematical Model-Based Automated Assessment of Fractional Flow Reserve

Noninvasive assessment of Fractional Flow Reserve is almost never applied in the Russian Federation due to the relative novelty and study insufficiency, lack of the appropriate resource base, specific necessary software and trained qualified personnel.

In 2015, scientists from the Institute of Numerical Mathematics RAS in collaboration with specialists of the I.M. Sechenov First Moscow State Medical University developed a noninvasive method of fractional flow reserve assessment based on a one-dimensional mathematical model. A model is constructed based on images derived from the coronary computed tomography angiography performed by standard protocol; the method is fully automated.

The aim of our study is to evaluate the diagnostic efficiency of this technique in clinical practice.

This is a pilot study; we are planning to enroll 30 patients: 13 of them underwent 64-slice computed tomography and are included retrospectively; 17 will be included prospectively, with a 640-slice CT scan. Specialists from the Laboratory of Mathematical Modeling will process CT images and evaluate noninvasive FFR. Ischemia is confirmed if FFR < 0.80 and disproved if FFR ≥ 0.80. After that, the prospective group of patients will be hospitalized for invasive FFR assessment as a reference standard; if ischemia is proved, patients will undergo stent implantation. In the retrospective group, patients already have invasive FFR values estimated.

Statistical analysis will be performed using R programming language packages (cran-r.project.com). Continuous variables will be presented as mean values ± standard deviations, order variables will be presented as medians with interquartile ranges in parentheses. We are going to use the D'Agostino-Pearson omnibus test for the assessment of normality of distribution and construct a Q-Q Plot. We will compare these two methods with the Bland-Altman analysis and ROC-analysis and will assess the degree of correlation with the Pearson's chi-squared.

The study should result in determining the sensitivity, specificity, positive and negative predictive values of the method.

After the active phase of the research is done, we are planning to proceed observation on the prospective group of patients to verify the endpoints.

Inclusion criteria

• Patients providing written informed consent
• Scheduled to undergo clinically-indicated non-emergent invasive coronary angiography (ICA)
• Has undergone >640 multidetector CCTA within 60 days prior to ICA
• No cardiac interventional therapy between the CCTA and ICA

Exclusion criteria

• Prior coronary artery bypass graft (CABG) surgery
• Prior percutaneous coronary intervention (PCI) for which suspected coronary artery lesion(s) are within a stented coronary vessel
• Contraindication to adenosine, including 2nd or 3rd-degree heart block; sick sinus syndrome; long QT syndrome; severe hypotension, severe asthma, severe COPD or bronchodilator-dependent COPD
• Suspicion of acute coronary syndrome (acute myocardial infarction and unstable angina)
• Recent prior myocardial infarction within 40 days of ICA
• Known complex congenital heart disease
• Prior pacemaker or internal defibrillator lead implantation
• Prosthetic heart valve
• Significant arrhythmia or tachycardia
• Impaired chronic renal function (serum creatinine >1.5 mg/dl
• Patients with known anaphylactic allergy to iodinated contrast
• Pregnancy or unknown pregnancy status
• Body mass index >35
• Patient requires an emergent procedure
• Evidence of ongoing or active clinical instability, including acute chest pain (sudden onset), cardiogenic shock, unstable blood pressure with systolic blood pressure <90 mmHg, and severe congestive heart failure (NYHA III or IV) or acute pulmonary edema
• Any active, serious, life-threatening disease with a life expectancy of less than 2 months
• Inability to comply with study procedures