Coronary Fractional Flow Reserve Measurement Research Articles

D-14 | Efficacy of contrast Diastolic Hyperemia-Free Ratio (Contrast - DFR) in comparison to coronary Fractional Flow Reserve with adenosine and Diastolic Hyperemia-Free Ratio (DFR)

BackgroundCoronary fractional flow reserve (FFR) is recommended as the gold standard method in evaluating intermediate coronary stenosis. Various methodologies have been reported using Diastolic Hyperemia – Free Ratio (DFR) and Instantaneous wave - free ratio.AimTo compare the contrast induced Pd/Pa ratio (DFR) with DFR and FFR.MethodsWe enrolled 19 consecutive patients with 20 intermediate lesions who underwent Diastolic pressure ratio measurement using DFR baseline Pd/Pa was calculated. A single contrast medium injection of 6 ml (3 ml/s) was performed manually and a Contrast DFR was measured within 10 seconds of injection.Following which coronary FFR measurement was performed using intravenous injection of adenosine to induce maximal hyperemia using 140 mcg/kg/min for 2 minutes and when it was ≤ 0.80, the intermediate lesion was considered as significant.Abnormal DFR was defined as cut off value 0.89, Contrast DFR as cut off value 0.80, FFR as cut off value 0.80.ResultsDiastolic pressure ratio was identified as significant in 10 lesions of 20 (50%) with a mean of 0.89 (range:0.66-1). The Contrast DFR was identified significant in 9 lesions of 20 (45%) with a mean of 0.80 (range of 0.67-0.97). FFR was abnormal in 9 lesions of 20 (45%) with a mean of 0.82 (range 0.63-0.97). A substantial positive correlation between FFR and contrast DFR values was detected (0.76) versus comparing correlation of DFR versus FFR (0.59).ConclusionsDisclosuresT. Raxwal Nothing to disclose. D. Parekh Nothing to disclose. R. M. Akel Nothing to disclose. BackgroundCoronary fractional flow reserve (FFR) is recommended as the gold standard method in evaluating intermediate coronary stenosis. Various methodologies have been reported using Diastolic Hyperemia – Free Ratio (DFR) and Instantaneous wave - free ratio. Coronary fractional flow reserve (FFR) is recommended as the gold standard method in evaluating intermediate coronary stenosis. Various methodologies have been reported using Diastolic Hyperemia – Free Ratio (DFR) and Instantaneous wave - free ratio. AimTo compare the contrast induced Pd/Pa ratio (DFR) with DFR and FFR. To compare the contrast induced Pd/Pa ratio (DFR) with DFR and FFR. MethodsWe enrolled 19 consecutive patients with 20 intermediate lesions who underwent Diastolic pressure ratio measurement using DFR baseline Pd/Pa was calculated. A single contrast medium injection of 6 ml (3 ml/s) was performed manually and a Contrast DFR was measured within 10 seconds of injection.Following which coronary FFR measurement was performed using intravenous injection of adenosine to induce maximal hyperemia using 140 mcg/kg/min for 2 minutes and when it was ≤ 0.80, the intermediate lesion was considered as significant.Abnormal DFR was defined as cut off value 0.89, Contrast DFR as cut off value 0.80, FFR as cut off value 0.80. We enrolled 19 consecutive patients with 20 intermediate lesions who underwent Diastolic pressure ratio measurement using DFR baseline Pd/Pa was calculated. A single contrast medium injection of 6 ml (3 ml/s) was performed manually and a Contrast DFR was measured within 10 seconds of injection. Following which coronary FFR measurement was performed using intravenous injection of adenosine to induce maximal hyperemia using 140 mcg/kg/min for 2 minutes and when it was ≤ 0.80, the intermediate lesion was considered as significant. Abnormal DFR was defined as cut off value 0.89, Contrast DFR as cut off value 0.80, FFR as cut off value 0.80. ResultsDiastolic pressure ratio was identified as significant in 10 lesions of 20 (50%) with a mean of 0.89 (range:0.66-1). The Contrast DFR was identified significant in 9 lesions of 20 (45%) with a mean of 0.80 (range of 0.67-0.97). FFR was abnormal in 9 lesions of 20 (45%) with a mean of 0.82 (range 0.63-0.97). A substantial positive correlation between FFR and contrast DFR values was detected (0.76) versus comparing correlation of DFR versus FFR (0.59). Diastolic pressure ratio was identified as significant in 10 lesions of 20 (50%) with a mean of 0.89 (range:0.66-1). The Contrast DFR was identified significant in 9 lesions of 20 (45%) with a mean of 0.80 (range of 0.67-0.97). FFR was abnormal in 9 lesions of 20 (45%) with a mean of 0.82 (range 0.63-0.97). A substantial positive correlation between FFR and contrast DFR values was detected (0.76) versus comparing correlation of DFR versus FFR (0.59). Conclusions DisclosuresT. Raxwal Nothing to disclose. D. Parekh Nothing to disclose. R. M. Akel Nothing to disclose. T. Raxwal Nothing to disclose. D. Parekh Nothing to disclose. R. M. Akel Nothing to disclose.

Cardiac perfusion by positron emission tomography.

Myocardial perfusion imaging (MPI) with positron emission tomography (PET) is an established tool for evaluation of obstructive coronary artery disease (CAD). The contemporary 3-dimensional scanner technology and the state-of-the-art MPI radionuclide tracers and pharmacological stress agents, as well as the cutting-edge image reconstruction techniques and data analysis software, have all enabled accurate, reliable and reproducible quantification of absolute myocardial blood flow (MBF), and henceforth calculation of myocardial flow reserve (MFR) in several clinical scenarios. In patients with suspected coronary artery disease, both absolute stress MBF and MFR can identify myocardial territories subtended by epicardial coronary arteries with haemodynamically significant stenosis, as defined by invasive coronary fractional flow reserve measurement. In particular, absolute stress MBF and MFR offered incremental prognostic information for predicting adverse cardiac outcome, and hence for better patient risk stratification, over those provided by traditional clinical risk predictors. This article reviews the available evidence to support the translation of the current techniques and technologies into a useful decision-making tool in real-world clinical practice.

Frontal QRS-T angle is related with hemodynamic significance of coronary artery stenosis in patients with single vessel disease.

Objective:Fractional flow reserve (FFR) measurement is used to decide the hemodynamic significance of coronary artery lesion. QRS-T angle (QRSTa) is a novel marker of myocardial repolarization abnormality and is affected by obstructive coronary artery disease. The aim of the present study was to evaluate the association between QRSTa and coronary FFR measurement in patients with isolated left anterior descending (LAD) artery stenosis.Methods:A total of 197 patients undergoing FFR measurement for isolated LAD artery stenosis were retrospectively enrolled in the present study. According to FFR value, patients were divided into two groups as 139 patients with normal FFR (>0.80, group 1) and 58 patients with low FFR (≤0.80, group 2). A 12-lead surface electrocardiography of all subjects that had been recorded before performing coronary angiography was evaluated to measure QRSTa, as well as baseline demographic and clinical variables.Results:The mean age of group 2 was significantly higher than that of group 1 (61±11 and 64±11, p=0.044). While there were no differences in heart rate, QRS duration, and corrected QT interval between the two groups, QT interval [377 (359–397) and 379 (367–410), p=0.045] and frontal QRSTa [59 (10–120) and 86 (22–132), p<0.001] were higher in group 2. QT interval [odds ratio (OR)=1.046, 95% confidence interval (CI)=1.010–1.084, p=0.012] and frontal QRSTa (OR=1.025, 95% CI=1.010–1.041, p=0.001) were found to be independent predictors of low FFR value in multivariate logistic regression analysis.Conclusion:In the present study, FFR measurement was demonstrated to be correlated with wide QRSTa as a noninvasive and easy method. Thus, we suggest that the results of FFR measurement as an invasive modality can be previously predicted with a simple electrocardiographic evaluation, such as QRSTa.

Coronary fractional flow reserve measurements of a stenosed side branch: a computational study investigating the influence of the bifurcation angle.

BackgroundCoronary hemodynamics and physiology specific for bifurcation lesions was not well understood. To investigate the influence of the bifurcation angle on the intracoronary hemodynamics of side branch (SB) lesions computational fluid dynamics simulations were performed.MethodsA parametric model representing a left anterior descending—first diagonal coronary bifurcation lesion was created according to the literature. Diameters obeyed fractal branching laws. Proximal and distal main branch (DMB) stenoses were both set at 60 %. We varied the distal bifurcation angles (40°, 55°, and 70°), the flow splits to the DMB and SB (55 %:45 %, 65 %:35 %, and 75 %:25 %), and the SB stenoses (40, 60, and 80 %), resulting in 27 simulations. Fractional flow reserve, defined as the ratio between the mean distal stenosis and mean aortic pressure during maximal hyperemia, was calculated for the DMB and SB (FFRSB) for all simulations.ResultsThe largest differences in FFRSB comparing the largest and smallest bifurcation angles were 0.02 (in cases with 40 % SB stenosis, irrespective of the assumed flow split) and 0.05 (in cases with 60 % SB stenosis, flow split 55 %:45 %). When the SB stenosis was 80 %, the difference in FFRSB between the largest and smallest bifurcation angle was 0.33 (flow split 55 %:45 %). By describing the ΔPSB−QSB relationship using a quadratic curve for cases with 80 % SB stenosis, we found that the curve was steeper (i.e. higher flow resistance) when bifurcation angle increases (ΔP = 0.451*Q + 0.010*Q2 and ΔP = 0.687*Q + 0.017*Q2 for 40° and 70° bifurcation angle, respectively). Our analyses revealed complex hemodynamics in all cases with evident counter-rotating helical flow structures. Larger bifurcation angles resulted in more pronounced helical flow structures (i.e. higher helicity intensity), when 60 or 80 % SB stenoses were present. A good correlation (R2 = 0.80) between the SB pressure drop and helicity intensity was also found.ConclusionsOur analyses showed that, in bifurcation lesions with 60 % MB stenosis and 80 % SB stenosis, SB pressure drop is higher for larger bifurcation angles suggesting higher flow resistance (i.e. curves describing the ΔPSB−QSB relationship being steeper). When the SB stenosis is mild (40 %) or moderate (60 %), SB resistance is minimally influenced by the bifurcation angle, with differences not being clinically meaningful. Our findings also highlighted the complex interplay between anatomy, pressure drops, and blood flow helicity in bifurcations.

Usefulness of Coronary Fractional Flow Reserve Measurement Using the Diagnostic Catheter

Usefulness of Coronary Fractional Flow Reserve Measurement Using the Diagnostic Catheter

An angiographic technique for coronary fractional flow reserve measurement: in vivo validation

Fractional flow reserve (FFR) is an important prognostic determinant in a clinical setting. However, its measurement currently requires the use of invasive pressure wire, while an angiographic technique based on first-pass distribution analysis and scaling laws can be used to measure FFR using only image data. Eight anesthetized swine were instrumented with flow probe on the proximal segment of the left anterior descending (LAD) coronary arteries. Volumetric blood flow from the flow probe (Qp), coronary pressure (Pa) and right atrium pressure (Pv) were continuously recorded. Flow probe-based FFR (FFRq) was measured from the ratio of flow with and without stenosis. To determine the angiography-based FFR (FFRa), the ratio of blood flow in the presence of a stenosis (QS) to theoretically normal blood flow (QN) was calculated. A region of interest in the LAD arterial bed was drawn to generate time-density curves using angiographic images. QS was measured using a time-density curve and the assumption that blood was momentarily replaced with contrast agent during the injection. QN was estimated from the total coronary arterial volume using scaling laws. Pressure-wire measurements of FFR (FFRp), which was calculated from the ratio of distal coronary pressure (Pd) divided by proximal pressure (Pa), were continuously obtained during the study. A total of 54 measurements of FFRa, FFRp, and FFRq were taken. FFRa showed a good correlation with FFRq (FFRa = 0.97 FFRq +0.06, r(2) = 0.80, p < 0.001), although FFRp overestimated the FFRq (FFRp = 0.657 FFRq + 0.313, r(2) = 0.710, p < 0.0001). Additionally, the Bland-Altman analysis showed a close agreement between FFRa and FFRq. This angiographic technique to measure FFR can potentially be used to evaluate both anatomical and physiological assessments of a coronary stenosis during routine diagnostic cardiac catheterization that requires no pressure wires.

Usefulness of Coronary Fractional Flow Reserve Measurements in Guiding Clinical Decisions in Intermediate or Equivocal Left Main Coronary Stenoses

The objectives of this study were to evaluate the usefulness of fractional flow reserve (FFR) measurements to guide the clinical decision in patients with intermediate left main coronary artery (LMCA) stenosis and to determine the predictors of major adverse cardiac events (MACE) -- cardiac death, myocardial infarction, coronary revascularization -- in such cases; 142 consecutive patients with intermediate LMCA stenosis (mean percent diameter stenosis 42 +/- 13%) were included. All patients underwent FFR measurement after intracoronary administration of adenosine at a dose > or =30 microg. The clinical decisions were based on FFR as follows: coronary revascularization was recommended if FFR was <0.75, medical treatment if FFR was >0.80, and individualized decision based on additional clinical data if FFR was between 0.75 and 0.80. Mean FFR was 0.81 +/- 0.09 after the administration of 176 +/- 99 microg of adenosine. Based on FFR results, 60 patients (42%) underwent coronary revascularization, and 82 patients (58%) received medical treatment. At 14 +/- 11 months follow-up, the incidence of MACE related to the LMCA stenosis was 13% in the medical treatment group and 7% in the revascularization group (p = 0.27). The incidence of cardiac death or myocardial infarction was 6% in the medical treatment group and 7% in the revascularization group (p = 0.70). In the medical treatment group, with MACE had received a lower dose of intracoronary adenosine (86 +/- 57 vs 167 +/- 102 microg; odds ratio 1.39 for each decrease of 30 microg of intracoronary adenosine, 95% confidence interval 1.02 to 1.89) and more frequently had diabetes (55% vs 21%; odds ratio 4.40, 95% confidence interval 1.17 to 16.42). In conclusion, FFR measurement is helpful in guiding the decision whether to revascularize patients with intermediate LMCA stenosis. However, patients with diabetes remain at higher risk, and higher doses than previously recommended of intracoronary adenosine might have to be used in the evaluation of LMCA stenosis.

Abstract 911: Usefulness of Coronary Fractional Flow Reserve Measurements to Guide Clinical Decisions in Intermediate Left Main Coronary Stenoses. Results of a Study Including 142 Consecutive Patients

Background: Limited data exist on the use of fractional flow reserve (FFR) measurements to guide clinical decisions in patients with intermediate left main coronary artery (LMCA) stenosis. Objectives: To evaluate the usefulness of FFR measurements to guide the clinical decision in patients with intermediate LMCA stenosis and to determine the predictors of major adverse cardiac events [MACE] (cardiac death, myocardial infarction, coronary revascularization) in such cases. Methods: A total of 142 consecutive patients (mean age 62 ± 10 yrs) with intermediate LMCA stenosis (mean percent diameter stenosis 42 ± 13%) were included. All patients underwent FFR measurement after intracoronary (ic) administration of adenosine at a dose ≥30 μg. Special care was taken in cases with ostial lesions to pull the catheter out of the LMCA after adenosine administration. The clinical decisions were based on FFR as follows: coronary revascularization was recommended if FFR was &lt;0.75, medical treatment if FFR was &gt;0.80, and individualized decision based on additional clinical data if FFR was between 0.75 and 0.80. The occurrence of MACE was evaluated at 14 ± 11 months follow-up. Results: Mean FFR was 0.81 ± 0.09 after the administration of a mean dose of 176 ± 99 μg of ic adenosine. Based on FFR results, sixty patients (42%) underwent coronary revascularization and 82 patients (58%) received medical treatment. At follow-up, the incidence of MACE related to the LMCA stenosis was 13% in the medical treatment group and 7% in the coronary revascularization group (p=0.27). The incidence of cardiac death and myocardial infarction was 7% in both groups (p=1.0). In the medical treatment group, patients with MACE had received a lower dose of ic adenosine (86 ± 57 μg vs. 167 ± 102 μg, OR: 1.39 for each decrease of 30 μg of ic adenosine, 95% CI 1.02–1.89, p=0.04) and were more frequently diabetics (55% vs. 21%, OR: 4.40, 95% CI 1.17–16.42, p=0.02). Conclusions: FFR measurement is helpful in guiding the decision as to whether to revascularize patients with intermediate LMCA stenosis. However, diabetic patients remain at higher risk, and higher doses than previously recommended of ic adenosine should be used in the evaluation of LMCA to avoid cardiac events due to underestimation of stenosis severity.