Impact of coronary bifurcation angle on stent malapposition in a randomized comparison between proximal optimization technique followed by side branch dilatation and kissing balloon inflation.

Background: The impact of coronary bifurcation angle (BA) on incomplete stent apposition (ISA) after crossover stenting followed by side branch (SB) intervention has not been established. Methods: A total of 100 crossover stentings randomly treated with proximal optimization technique followed by short balloon dilation in the SB (POT-SBD group, 48 patients) and final kissing balloon technique (KBT group, 52 patients) were analyzed in the PROPOT trial. Major ISA with maximum distance > 400 µm and its location was determined using optical coherence tomography before SB intervention and at the final procedure. The BA was defined as the angle between the distal main vessel and SB. Optimal POT was determined when the difference in stent volume index between the proximal and distal bifurcation was greater than the median value (0.86 mm3/mm) before SB intervention. Result: Major ISA was more frequently observed in the POT-SBD than in the KBT group (35% versus 17%, p < 0.05). In the POT-SBD group, worsening ISA after SBD was prominent at the distal bifurcation. The BA was an independent predictor of major ISA (odds ratio 1.04, 95% confidence interval 1.00-1.07, p < 0.05) with a cut-off value of 59.5° (p < 0.05). However, the cases treated with optimal POT in the short BA (<60°) indicated the lowest incidence of major ISA. In the KBT group, BA had no significant impact. Conclusion: A wide BA has a potential risk for the occurrence of major ISA after POT followed by SBD in coronary bifurcation stenting.

Multimodality imaging to identify lipid-rich coronary plaques and predict periprocedural myocardial injury: Association between near-infrared spectroscopy and coronary computed tomography angiography.

Background: This study compares the efficacy of coronary computed tomography angiography (CCTA) and near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) in patients with significant coronary stenosis for predicting periprocedural myocardial injury during percutaneous coronary intervention (PCI). Methods: We prospectively enrolled 107 patients who underwent CCTA before PCI and performed NIRS-IVUS during PCI. Based on the maximal lipid core burden index for any 4-mm longitudinal segments (maxLCBI4mm) in the culprit lesion, we divided the patients into two groups: lipid-rich plaque (LRP) group (maxLCBI4mm ≥ 400; n = 48) and no-LRP group (maxLCBI4mm < 400; n = 59). Periprocedural myocardial injury was a postprocedural cardiac troponin T (cTnT) elevation of ≥5 times the upper limit of normal. Results: The LRP group had a significantly higher cTnT (p = 0.026), lower CT density (p < 0.001), larger percentage atheroma volume (PAV) by NIRS-IVUS (p = 0.036), and larger remodeling index measured by both CCTA (p = 0.020) and NIRS-IVUS (p < 0.001). A significant negative linear correlation was found between maxLCBI4mm and CT density (rho = -0.552, p < 0.001). Multivariable logistic regression analysis identified maxLCBI4mm [odds ratio (OR): 1.006, p = 0.003] and PAV (OR: 1.125, p = 0.014) as independent predictors of periprocedural myocardial injury, while CT density was not an independent predictor (OR: 0.991, p = 0.22). Conclusion: CCTA and NIRS-IVUS correlated well to identify LRP in culprit lesions. However, NIRS-IVUS was more competent in predicting the risk of periprocedural myocardial injury.

Diagnostic Accuracy of Artificial Intelligence-Based Angiography-Derived Fractional Flow Reserve Using Pressure Wire-Based Fractional Flow Reserve as a Reference.

BACKGROUND: Angiographic fractional flow reserve (angioFFR) is a novel artificial intelligence (AI)-based angiography-derived fractional flow reserve (FFR) application. We investigated the diagnostic accuracy of angioFFR to detect hemodynamically relevant coronary artery disease.Methods and Results: Consecutive patients with 30-90% angiographic stenoses and invasive FFR measurements were included in this prospective, single-center study conducted between November 2018 and February 2020. Diagnostic accuracy was assessed using invasive FFR as the reference standard. In patients undergoing percutaneous coronary intervention, gradients of invasive FFR and angioFFR in the pre-senting segments were compared. We assessed 253 vessels (200 patients). The accuracy of angioFFR was 87.7% (95% confidence interval [CI] 83.1-91.5%), with a sensitivity of 76.8% (95% CI 67.1-84.9%), specificity of 94.3% (95% CI 89.5-97.4%), and area under the curve of 0.90 (95% CI 0.86-0.93%). AngioFFR was well correlated with invasive FFR (r=0.76; 95% CI 0.71-0.81; P<0.001). The agreement was 0.003 (limits of agreement: -0.13, 0.14). The FFR gradients of angioFFR and invasive FFR were comparable (n=51; mean [±SD] 0.22±0.10 vs. 0.22±0.11, respectively; P=0.87). CONCLUSIONS: AI-based angioFFR showed good diagnostic accuracy for detecting hemodynamically relevant stenosis using invasive FFR as the reference standard. The gradients of invasive FFR and angioFFR in the pre-stenting segments were comparable.

Incidence and natural history of coronary evagination after implanted biodegradable polymer sirolimus-eluting stent.

Aims: The incidence and temporal change in coronary evagination (CE) after first-generation drug-eluting stent implantation is well established, whereas that after biodegradable polymer sirolimus-eluting stent (BP-SES) implantation has not yet been evaluated. The aim of this study is to assess the incidence and natural history of CE after BP-SES implantation. Methods and results: In this multicenter registry, stable coronary lesions treated by Ultimaster BP-SES were evaluated by serial optical frequency domain imaging (OFDI) (at 0-1-12 or 0-3-12 months) and the incidence of CE was assessed. Coronary evagination was defined as the presence of an outward bulge in luminal vessel contour between apposed struts according to the following criteria: (i) evagination depth ≥10% of nominal stent diameter and (ii) evagination length ≥3.0 mm. Optical frequency domain imaging was obtained in 98, 47, 49, and 87 lesions at 0, 1, 3, and 12 months, respectively. Coronary evagination was observed in 20 (42.6%) and 12 (24.5%) lesions at 1 and 3 months, respectively, and all but one CE had resolved at 12 months. At 12 months, the mean CE area was almost zero and the mean malapposed stent area was also decreased. Comparison of the serial OFDI images indicated that CEs originated mostly from acute stent malapposition or coronary dissection behind the implanted stent. Conclusions: In stable lesions, CE was occasionally observed with Ultimaster BP-SES at 1-3 months but mostly resolved within 12 months, without late-acquired stent malapposition. These findings suggest the safety and feasibility of biodegradable polymer coating on DES.

Development of 60 MHz integrated backscatter intravascular ultrasound and tissue characterization of attenuated signal coronary plaques that cause myocardial injury after percutaneous coronary intervention.

The purpose of the present study was to develop a 60 MHz integrated backscatter intravascular ultrasound (IB-IVUS) and to evaluate its usefulness for the detection of lipid area with backward attenuation of ultrasound signal (AT) that for the prediction of post-procedural myocardial injury (PMI) after percutaneous coronary intervention (PCI). In a pathological study, images were acquired from 221 cross-sections of 18 coronary arteries from 13 cadavers obtained at autopsy. In the clinical training study, we compared non-targeted plaques in 38 patients by a previous IB-IVUS system (38 MHz) and a new IB-IVUS system (60 MHz). In the clinical testing study, we included 70 consecutive patients who underwent PCI. Serum troponin-I was measured just before and 24 h after PCI to evaluate PMI. As the % microcalcification + % cholesterol cleft area increased, the attenuation of IB values increased (r = 0.56, p < 0.001). The slopes of regression lines of the area of each tissue component between 38 and 60 MHz IB-IVUS were excellent. The lipid pool area with AT tended to be more useful than that of the conventional lipid pool area for the prediction of PMI (p = 0.11). We developed a 60 MHz IB-IVUS imaging system for tissue characterization of coronary plaques. Cutoff value of purple color was the most reliable value for the prediction of PMI.

Effect of proximal optimization technique on coronary bifurcation stent failure: Insights from the multicenter randomized PROPOT trial.

OBJECTIVE: We investigated the effect of proximal optimization technique (POT) on coronary bifurcation stent failure (BSF) in cross-over stenting by comparing with the kissing balloon technique (KBT) in a multicenter randomized PROPOT trial. BACKGROUND: POT is recommended due to increased certainty for optimal stent expansion and side branch (SB) wiring. METHODS: We randomized 120 patients treated with crossover stenting into the POT group, which was followed by SB dilation (SBD), and the KBT group. Finally, 52 and 57 patients were analyzed by optical coherence tomography before SBD and at the final procedure, respectively. Composite BSF was defined as a maximal malapposition distance of >400 µm, or malapposed and SB-jailed strut rates of >5.95% and >21.4%, respectively. RESULTS: Composite BSF before SBD in the POT and KBT groups was observed in 29% and 26% of patients, respectively. In the POT group, differences in stent volumetric index between the proximal and distal bifurcation (odds ratio [OR] 60.35, 95% confidential interval [CI] 0.13-0.93, p = 0.036) and between the proximal bifurcation and bifurcation core (OR: 3.68, 95% CI: 1.01-13.40, p = 0.048) were identified as independent risk factors. Composite BSF at final in 27% and 32%, and unplanned additional procedures in 38% and 25% were observed, respectively. Composite BSF before SBD was a risk factor for the former (OR: 6.33, 95% CI: 1.10-36.50, p = 0.039) and the latter (OR: 6.43, 95% CI: 1.25-33.10, p = 0.026) in the POT group. CONCLUSION: POT did not result in a favorable trend in BSF. Insufficient expansion of the bifurcation core after POT was associated with BSF.

A serial optical frequency-domain imaging study of early and late vascular responses to bioresorbable-polymer sirolimus-eluting stents for the treatment of acute myocardial infarction and stable coronary artery disease patients: results of the MECHANISM-ULTIMASTER study.

The purpose of this study was to assess early and late vascular healing in response to bioresorbable-polymer sirolimus-eluting stents (BP-SESs) for the treatment of patients with ST-elevation myocardial infarction (STEMI) and stable coronary artery disease (CAD). A total of 106 patients with STEMI and 101 patients with stable-CAD were enrolled. Optical frequency-domain images were acquired at baseline, at 1- or 3-month follow-up, and at 12-month follow-up. In the STEMI and CAD cohorts, the percentage of uncovered struts (%US) was significantly and remarkably decreased during early two points and at 12-month (the STEMI cohort: 1-month: 18.75 ± 0.78%, 3-month: 10.19 ± 0.77%, 12-month: 1.80 ± 0.72%; p < 0.001, the CAD cohort: 1-month: 9.44 ± 0.78%, 3-month: 7.78 ± 0.78%, 12-month: 1.07 ± 0.73%; p < 0.001 respectively). The average peri-strut low-intensity area (PLIA) score in the STEMI cohort was significantly decreased during follow-up period (1.90 ± 1.14, 1.18 ± 1.25, and 1.01 ± 0.72; p ≤ 0.001), whereas the one in the CAD cohort was not significantly changed (0.89 ± 1.24, 0.67 ± 1.07, and 0.64 ± 0.72; p = 0.59). In comparison with both groups, differences of %US and PLIA score at early two points were almost disappeared or close at 12 months. The strut-coverage and healing processes in the early phase after BP-SES implantation were significantly improved in both cohorts, especially markedly in STEMI patients. At 1 year, qualitatively and quantitatively consistent neointimal coverage was achieved in both pathogenetic groups.

The importance of side branch preservation in the treatment of chronic total occlusions with bifurcation lesions.

OBJECTIVES: The aim of this study was to identify the predictive factors for suboptimal result in side branch (SB) in chronic total occlusion (CTO) bifurcation lesions and clinical outcomes of patients with suboptimal result in SB. BACKGROUND: There is little evidence on the optimal strategy for bifurcation lesions in CTO. METHODS: We retrospectively reviewed 314 consecutive bifurcation lesions in CTO with SB ≥ 2.5 mm in 3 hospitals from March 2010 to June 2018. Patients were divided into the two groups based on the suboptimal SB treatment (SST) and optimal SB treatment (OST) groups. The baseline characteristics, procedural and clinical outcomes were compared between the two groups. This study also evaluated the predictors of suboptimal result in SB. RESULTS: Suboptimal result in SB occurred in 47 cases. Presence of stenosis in SB, bifurcations located within the occluded segment and sub-intimal tracking at SB ostium was an independent predictor of suboptimal result in SB. The cumulative incidence of target lesion revascularization (TLR) in all lesions was not significantly different between the two groups, however, TLR in right coronary artery (RCA) was significantly higher in the SST group. In the Cox regression analysis, suboptimal result in SB in RCA and sub-intimal tracking were independent predictors of TLR for MB. In patients with bifurcations located within the occluded segment, usage of two-stent technique was significantly lower in the SST group. CONCLUSIONS: Meticulous procedures are required for SB preservation to improve not only SB prognosis but also MB, especially in RCA.

Stress Myocardial Perfusion Imaging Interpretation From the Viewpoint of Fractional Flow Reserve.

BACKGROUND: Myocardial perfusion imaging (MPI) and fractional flow reserve (FFR) are established approaches to the assessment of myocardial ischemia. Recently, various FFR cutoff values were proposed, but the diagnostic accuracy of MPI in identifying positive FFR using various cutoff values is not well established.Methods and Results:We retrospectively studied 273 patients who underwent stress MPI and FFR within a 3-month period. Results for FFR were obtained from 218 left anterior descending artery (LAD) lesions and 207 non-LAD lesions. Stress MPI and FFR demonstrated a good correlation in the detection of myocardial ischemia. However, the positive predictive value (PPV) of FFR for detecting MPI-positive lesions at the optimal FFR thresholds was insufficient (44% for LAD and 65% for non-LAD lesions). This was caused by a sharp drop in PPV at an FFR threshold of 0.7 or more. Notably, 41% of the lesions with normal MPI demonstrated FFRs <0.80. However, MPI-negative lesions had an extremely low lesion rate with FFR <0.65 (6%). Conversely, 78% and 41% of MPI-positive lesions had FFR <0.80 and <0.65, respectively. CONCLUSIONS: The data confirmed that decisions based on MPI are reasonable because MPI-negative patients have an extremely low rate of lesions with a FFR below the cutoff point for a hard event, and MPI-positive lesions include many lesions with FFR <0.65.

Proximal optimisation technique versus final kissing balloon inflation in coronary bifurcation lesions: the randomised, multicentre PROPOT trial.

BACKGROUND: Clinical implications of the proximal optimisation technique (POT) for bifurcation lesions have not been investigated in a randomised controlled trial. AIMS: This study aimed to investigate whether POT is superior in terms of stent apposition compared with the conventional kissing balloon technique (KBT) in real-life bifurcation lesions using optical coherence tomography (OCT). METHODS: A total of 120 patients from 15 centres were randomised into two groups - POT followed by side branch dilation or KBT. Finally, 57 and 58 patients in the POT and KBT groups, respectively, were analysed. OCT was performed at baseline, immediately after wire recrossing to the side branch, and at the final procedure. RESULTS: The primary endpoint was the rate of malapposed struts assessed by the final OCT. The rate of malapposed struts did not differ between the POT and KBT groups (in-stent proximal site: 10.4% vs 7.7%, p=0.33; bifurcation core: 1.4% vs 1.1%, p=0.67; core's distal edge: 6.2% vs 5.3%, p=0.59). More additional treatments were required among the POT group (40.4% vs 6.9%, p<0.01). At one-year follow-up, only one patient in each group underwent target lesion revascularisation (2.0% vs 1.9%). CONCLUSIONS: POT followed by side branch dilation did not show any advantages over conventional KBT in terms of stent apposition; however, excellent midterm clinical outcomes were observed in both strategies.

Accuracy of Intravascular Ultrasound-Based Fractional Flow Reserve in Identifying Hemodynamic Significance of Coronary Stenosis.

BACKGROUND: Ultrasonic flow ratio (UFR) is a novel method for fast computation of fractional flow reserve (FFR) from intravascular ultrasound images. The objective of this study is to evaluate the diagnostic performance of UFR using wire-based FFR as the reference. METHODS: Post hoc computation of UFR was performed in consecutive patients with both intravascular ultrasound and FFR measurement in a core lab while the analysts were blinded to FFR. RESULTS: A total of 167 paired comparisons between UFR and FFR from 94 patients were obtained. Median FFR was 0.80 (interquartile range, 0.68-0.89) and 50.3% had a FFR≤0.80. Median UFR was 0.81 (interquartile range, 0.69-0.91), and UFR showed strong correlation with FFR (r=0.87; P<0.001). The area under the curve was higher for UFR than intravascular ultrasound-derived minimal lumen area (0.97 versus 0.89, P<0.001). The diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for UFR to identify FFR≤0.80 was 92% (95% CI, 87-96), 91% (95% CI, 82-96), 96% (95% CI, 90-99), 96% (95% CI, 89-99), 91% (95% CI, 93-96), 25.0 (95% CI, 8.2-76.2), and 0.10 (95% CI, 0.05-0.20), respectively. The agreement between UFR and FFR was independent of lesion locations (P=0.48), prior myocardial infarction (P=0.29), and imaging catheters (P=0.22). Intraobserver and interobserver variability of UFR analysis was 0.00±0.03 and 0.01±0.03, respectively. Median UFR analysis time was 102 (interquartile range, 87-122) seconds. CONCLUSIONS: UFR had a strong correlation and good agreement with FFR. The fast computational time and excellent analysis reproducibility of UFR bears the potential of a wider adoption of integration of coronary imaging and physiology in the catheterization laboratory.

Determination of the Optimal Measurement Point for Fractional Flow Reserve Derived From CTA Using Pressure Wire Assessment as Reference.

BACKGROUND. For clinical decision making, it was recently recommended that values of fractional flow reserve (FFR) derived from coronary CTA (FFRCT) be measured 1-2 cm distal to the stenosis, given the potential for overestimation of ischemia when FFRCT values at far distal segments are used. Supporting data are, however, lacking. OBJECTIVE. The purpose of the present study was to evaluate the diagnostic performance of FFRCT values measured 1-2 cm distal to the stenosis and at more distal locations relative to invasive FFR values. METHODS. FFRCT and invasive FFR values for 365 vessels in 253 patients identified from the Assessing Diagnostic Value of Noninvasive FFRCT in Coronary Care (ADVANCE) registry were prospectively assessed. FFRCT values were measured 1-2 cm distal to the stenosis and at the pressure wire position and far distal segments. The diagnostic accuracy of FFRCT was assessed on the basis of the ROC AUC. The AUC of FFRCT was calculated using FFRCT as an explanatory variable and an invasive FFR of 0.80 or less as the dichotomous dependent variable. RESULTS. The AUC of FFRCT values measured 1-2 cm distal to the stenosis (0.85; 95% CI, 0.80-0.88) was higher (p = .002) than that of FFRCT values measured at far distal segments (0.80; 95% CI, 0.76-0.84) and similar (p = .16) to that of FFRCT values measured at the pressure wire position (0.86; 95% CI, 0.81-0.89). FFRCT values measured 1-2 cm distal to the stenosis and at far distal segments had sensitivity of 87% versus 92% (p = .003), specificity of 73% versus 42% (p < .001), PPV of 75% versus 59% (p < .001), and NPV of 86% versus 85% (p = .72), respectively. Subgroup analyses of lesions of the left anterior descending coronary artery, left circumflex coronary artery, and right coronary artery all showed improved specificity and PPV (all p < .005) for FFRCT values measured 1-2 cm distal to the stenosis compared with values measured at the pressure wire position. However, the AUC was higher for measurements obtained 1-2 cm distal to the stenosis versus those obtained at far distal segments, for left anterior descending coronary artery lesions (p < .001) but not for left circumflex coronary artery lesions (p = .27) or right coronary artery lesions (p = .91). CONCLUSION. The diagnostic performance of FFRCT values measured 1-2 cm distal to the stenosis was higher than that of FFRCT values measured at far distal segments and was similar to that of FFRCT values measured at the pressure wire position in evaluating ischemic status, particularly for left anterior descending coronary artery lesions. CLINICAL IMPACT. The present study supports recent recommendations from experts to use FFRCT measured 1-2 cm distal to the stenosis, rather than measurements obtained at far distal segments, in clinical decision making.

In vivo validation of resting full-cycle ratio and diastolic pressure ratio: simultaneous measurement with instantaneous wave-free ratio.

The diastolic pressure ratio (dPR) and resting full-cycle ratio (RFR) are considered to be almost identical to the instantaneous wave-free ratio (iFR) in the retrospective analysis of pooled data. The aim of this study was to investigate the direct comparison of iFR and these new resting indexes in real world practice. Two pressure wires were inserted and placed in the distal part of the same coronary artery. The measurement of the iFR and the other resting indexes was performed simultaneously. A total of 54 lesions from 23 patients were subject to physiological study. In 49 lesions, iFR and other resting indexes were also measured in hyperemic conditions. The general correlation between iFR and other resting indexes was excellent in both resting and hyperemic conditions (r2 = 0.99; mean difference - 0.001 ± 0.021; p < 0.001; and r2 = 0.99; mean difference - 0.012 ± 0.025; p < 0.001, respectively). This correlation was maintained in various subgroup analyses. A diagnostic change between iFR and other resting indexes occurred in three cases (3%) when a fixed cut-off point (≤ 0.89) was applied. There was no diagnostic change when a hybrid zone (0.86 ≤ iFR ≤ 0.93) was considered. The new resting indexes and iFR showed very high correlation in real world practice. A diagnostic change only occurred in three cases (3%) when a fixed cut-off point (≤ 0.89) was applied.

Comparisons of Nonhyperemic Pressure Ratios: Predicting Functional Results of Coronary Revascularization Using Longitudinal Vessel Interrogation.

OBJECTIVES: The aim of this study was to investigate the accuracy of pre-percutaneous coronary intervention (PCI) predicted nonhyperemic pressure ratios (NHPRs) with actual post-PCI NHPRs and to assess the efficacy of PCI strategy using pre-PCI NHPR pullback. BACKGROUND: Predicting the functional results of PCI is feasible using pre-PCI longitudinal vessel interrogation with the instantaneous wave-free ratio (iFR), a pressure-based, adenosine-free NHPR. However, the reliability of novel NHPRs (resting full-cycle ratio [RFR] and diastolic pressure ratio [dPR]) for this purpose remains uncertain. METHODS: In this prospective, multicenter, randomized controlled trial, vessels were randomly assigned to receive pre-PCI iFR, RFR, or dPR pullback (50 vessels each). The pre-PCI predicted NHPRs were compared with actual NHPRs after contemporary PCI using intravascular imaging. The number and the total length of treated lesions were compared between NHPR pullback-guided and angiography-guided strategies. RESULTS: The predicted NHPRs were strongly correlated with actual NHPRs: iFR, r = 0.83 (95% confidence interval: 0.72 to 0.90; p < 0.001); RFR, r = 0.84 (95% confidence interval: 0.73 to 0.91; p < 0.001), and dPR, r = 0.84 (95% confidence interval: 0.73 to 0.91; p < 0.001). The number and the total length of treated lesions were lower with the NHPR pullback strategy than with the angiography-guided strategy, leading to physiological improvement. CONCLUSIONS: Predicting functional PCI results on the basis of pre-procedural RFR and dPR pullbacks yields similar results to iFR. Compared with an angiography-guided strategy, a pullback-guided PCI strategy with any of the 3 NHPRs reduced the number and the total length of treated lesions. (Study to Examine Correlation Between Predictive Value and Post PCI Value of iFR, RFR and dPR; UMIN000033534).

Prediction of post-intervention fractional flow reserve in diffuse or sequential coronary stenosis considering the residual trans-stent pressure gradient: Post-intervention FFR in diffuse/sequential lesions.

AIMS: Prediction of post-intervention fractional flow reserve (FFR) in a diffuse or sequential coronary lesion is difficult due to complex haemodynamic interactions between individual stenoses. Furthermore, the existence of a residual intra-stent pressure gradient makes the prediction difficult. We developed an equation predicting the post-intervention FFR in a diffuse/sequential lesion by considering intra-stent FFR gradient. The present study aims to validate the equation in an in vitro model and in clinical data. METHODS AND RESULTS: In the in vitro experiment, three sequential coronary stenoses were made with a collateral flow. The correlation coefficient of the predicted FFR and the actual post-intervention FFR was 0.99, and the absolute difference was 0.008±0.006 (n=50). In the clinical data analysis, the correlation coefficient was 0.41, and the absolute difference was 0.06±0.05 (n=67). We applied a fixed value of intra-stent FFR gradient and a collateral flow index so that the equation can be used in clinical practice. The correlation coefficient became 0.28 and the absolute difference became 0.06±0.06. CONCLUSIONS: In clinical practice, prediction of post-intervention FFR in a diffuse/sequential lesion is difficult even when residual intra-stent pressure gradient is considered.

On-site evaluation of CT-based fractional flow reserve using simple boundary conditions for computational fluid dynamics.

Fractional flow reserve (FFR) is an established method for diagnosing physiological coronary artery stenosis. A method for computing FFR using coronary computed tomography (CT) images was recently developed. However, its calculation requires off-site supercomputer analysis. Here, we report the preliminary result of a method using simple estimation of boundary conditions. The lumen boundaries of the coronary arteries were semi-automatically delineated using full width at half maximum of CT number profiles. The computational fluid dynamics (CFD) of the blood flow was performed using the boundary conditions of a fixed pressure at the coronary ostium and flow rates at each outlet. The total inflow at the coronary ostium was estimated based on the uniform wall shear stress hypothesis and corrected using a hyperemic multiplier to gain a hyperemic flow rate. The flow distribution from a parent vessel to the downstream daughter vessels was determined according to Murray's law. FFR estimated by CFD was calculated as FFRCFD = Pd/Pa. We collected patients who underwent coronary CT and coronary angiography followed by invasively measured FFR and compared FFRCFD with FFR. Sensitivity, specificity, and correlations were assessed. A total of 48 patients and 72 arteries were assessed. The correlation coefficient of FFRCFD with FFR was 0.56. The cut-off value was ≤ 0.80, sensitivity was 59.1%, and specificity was 94.0%. CFD-based FFR using simple boundary conditions for on-site clinical computation provided FFRCFD values that were moderately correlated with invasively measured FFR.

Efficacy of plaque debulking for bifurcated or ostial lesions by directional coronary atherectomy prior to second-generation drug eluting stenting.

OBJECTIVES: We sought to evaluate the efficacy of plaque debulking by directional coronary atherectomy (DCA) prior to second-generation drug-eluting stent (DES) implantation for bifurcated coronary lesions. BACKGROUND: Percutaneous coronary intervention (PCI) for bifurcated lesions still remains complex and challenging in terms of restenosis or stent thrombosis regardless of whether simple or complex stenting is used. METHODS: Patients with bifurcated lesions were enrolled in this prospective multicenter registry. Pre-second-generation DES plaque debulking with a novel DCA catheter (ATHEROCUT®, Nipro Co., Osaka, Japan) was conducted. All patients were scheduled to perform a follow up angiography (9-12 month coronary angiography or coronary computed tomography). The primary end point was target vessel failure (TVF) at follow up. Secondary end points were procedure-related events and major adverse cardiac events at 1 year. RESULTS: A total of 77 patients with bifurcated lesions were enrolled. PCI with DCA was performed successfully in all cases without any major procedure-related event and only one case required complex stenting. The TVF rate at 9-12 month follow up was 3.9% (3 of 77) and those were all associated with revascularization of the target vessel. Restenosis was only observed at the ostium of the main-branch in three cases. No death, coronary artery bypass grafting, or myocardial infarction were reported for any patients within the first year. CONCLUSION: DCA before second-generation DES implantation can possibly avoid complex stenting and provide a good mid-term outcome in patients with bifurcated lesions.

QFR Versus FFR Derived From Computed Tomography for Functional Assessment of Coronary Artery Stenosis.

OBJECTIVES: The aim of this study was to compare diagnostic performance between quantitative flow ratio (QFR) derived from coronary angiography and fractional flow reserve derived from computed tomography (FFRCT) using fractional flow reserve (FFR) as the reference standard. BACKGROUND: QFR and FFRCT are recently developed, less invasive techniques for functional assessment of coronary artery disease. METHODS: QFR, FFRCT, and FFR were measured in 152 patients (233 vessels) with stable coronary artery disease. RESULTS: QFR was highly correlated with FFR (r = 0.78; p < 0.001), whereas FFRCT was moderately correlated with FFR (r = 0.63; p < 0.001). Both QFR and FFRCT showed moderately good agreement with FFR, presenting small values of mean difference but large values of root mean squared deviation (FFR-QFR, 0.02 ± 0.09; FFR-FFRCT, 0.03 ± 0.11). The sensitivity, specificity, positive predictive value, and negative predictive value of QFR ≤0.80 for predicting FFR ≤0.80 were 90%, 82%, 81%, and 90%, respectively. Those of FFRCT ≤0.80 for predicting FFR ≤0.80 were 82%, 70%, 70%, and 82%, respectively. The diagnostic accuracy of QFR ≤0.80 for predicting FFR ≤0.80 was 85% (95% confidence interval [CI]: 81% to 89%), whereas that of FFRCT ≤0.80 for predicting FFR ≤0.80 was 76% (95% CI: 70% to 80%). CONCLUSIONS: QFR and FFRCT showed significant correlation with FFR. Mismatches between QFR and FFR and between FFRCT and FFR were frequent.