Fractional flow reserve for the prediction of cardiac events after coronary stent implantation: results of a multivariate analysis

Angiography-based Fractional Flow Reserve for the Prediction of Clinical Outcomes After Drug-coated Balloon or Plain Old Balloon Angioplasty

BACKGROUND

AccuFFRangio is a novel method for fast computation of fractional flow reserve (FFR) based on coronary angiography and computational fluid dynamics. The association between the AccuFFRangio and clinical outcomes after drug-coated balloon (DCB) or plain old balloon angioplasty (POBA) remains to be investigated.

METHODS

This study included consecutive patients who underwent balloon angioplasty from December 2016 to October 2020. AccuFFRangio was calculated retrospectively based on the post-procedural angiography obtained immediately after angioplasty. The primary endpoint was major adverse cardiac events (MACE), defined as a composite of all-cause death, vessel-related myocardial infarction, and repeat target vessel revascularization.

RESULTS

A total of 169 patients were retrospectively analyzed in this study. Post-procedural AccuFFRangio (hazard ratio [HR] per 0.1 increase 0.33, 95% confidence interval [CI] 0.22-0.48, p < 0.001) was an independent predictor for MACE at 2-year follow-up. Post-procedural AccuFFRangio ≤ 0.87 was determined as the optimal cutoff value to predict MACE with an area under the curve (AUC) of 0.872 (95% CI 0.813-0.919, p < 0.001).

CONCLUSIONS

AccuFFRangio measured immediately after balloon angioplasty is a promising predictor of unfavorable clinical outcomes.

Physiologic Assessment After Percutaneous Coronary Interventions and Functionally Optimized Revascularization

Coronary physiologic assessment has become a standard of care for patients with coronary atherosclerotic disease. While most attention has focused on pre-interventional physiologic assessment to aid in revascularization decision-making, post-interventional physiologic assessment has not been as widely used, despite evidence supporting its role in assessment and optimization of the revascularization procedure. A thorough understanding of such evidence and ongoing studies would be crucial to incorporate post-interventional physiologic assessment into daily practice. Thus, this review provides a comprehensive overview of current evidence regarding the evolving role of physiologic assessment as a functional optimization tool for the entire revascularization process.

Coronary Physiology as Part of a State-of-the-Art Percutaneous Coronary Intervention Strategy: Lessons from SYNTAX II and Beyond

The use of coronary physiology allows for rational decision making at the time of PCI, contributing to better patient outcomes. Yet, coronary physiology is only one aspect of optimal revascularization. State-of-the-art PCI must also consider other important aspects such as intracoronary imaging guidance and specific procedural expertise, as tested in the SYNTAX II study. In this review, we highlight the technical aspects pertaining to the use of physiology as used in that trial and offer a glimpse into the future with emerging physiologic metrics, including functional coronary angiography, which have already established themselves as useful indices to guide decision making.

Intravascular Ultrasound-Based Fractional Flow Reserve for Predicting Prognosis after Percutaneous Coronary Intervention

AccuFFRivus is an alternative to fractional flow reserve (FFR) based on intravascular ultrasound (IVUS) images for functional assessment of coronary stenosis. However, its prognostic impact in patients undergoing percutaneous coronary intervention (PCI) is still unclear. This retrospective study aimed to investigate the capability of AccuFFRivus in predicting prognosis. AccuFFRivus was calculated based on postoperative angiographic and IVUS images. Vessel-oriented clinical events (VOCE) at 2 years were recorded and analyzed. A total of 131 participants with 131 vessels were included in the study. VOCE occurred in 15 patients during 2-year follow-up. AccuFFRivus after PCI (post-AccuFFRivus) was significantly higher in the non-VOCE group than in the VOCE group (0.95 ± 0.03 vs. 0.91 ± 0.02, p < 0.001). Multivariate Cox regression showed that AccuFFRivus ≤ 0.94 was a strong independent predictor of VOCE during 2-year follow-up (hazard ratio 23.76, 95% confidence interval: 3.04-185.81, p < 0.001). The left panel displays the Receiver operating characteristics (ROC) curves of postoperative parameters (post-AccuFFRivus and post-MLA) versus vessel-oriented clinical events (VOCE) occurrence within 2-year follow-up. The right panel demonstrates Kaplan-Meier curves of VOCE stratified by the optimal cut-off of post-AccuFFRivus.

Applied coronary physiology for planning and guidance of percutaneous coronary interventions. A clinical consensus statement from the European Association of Percutaneous Cardiovascular Interventions (EAPCI) of the European Society of Cardiology

The clinical value of fractional flow reserve and non-hyperaemic pressure ratios are well established in determining an indication for percutaneous coronary intervention (PCI) in patients with coronary artery disease (CAD). In addition, over the last 5 years we have witnessed a shift towards the use of physiology to enhance procedural planning, assess post-PCI functional results, and guide PCI optimisation. In this regard, clinical studies have reported compelling data supporting the use of longitudinal vessel analysis, obtained with pressure guidewire pullbacks, to better understand how obstructive CAD contributes to myocardial ischaemia, to establish the likelihood of functionally successful PCI, to identify the presence and location of residual flow-limiting stenoses and to predict long-term outcomes. The introduction of new functional coronary angiography tools, which merge angiographic information with fluid dynamic equations to deliver information equivalent to intracoronary pressure measurements, are now available and potentially also applicable to these endeavours. Furthermore, the ability of longitudinal vessel analysis to predict the functional results of stenting has played an integral role in the evolving field of simulated PCI. Nevertheless, it is important to have an awareness of the value and challenges of physiology-guided PCI in specific clinical and anatomical contexts. The main aim of this European Association of Percutaneous Cardiovascular Interventions clinical consensus statement is to offer up-to-date evidence and expert opinion on the use of applied coronary physiology for procedural PCI planning, disease pattern recognition and post-PCI optimisation.

Physiologic Assessment After Percutaneous Coronary Interventions and Functionally Optimized Revascularization

Coronary physiologic assessment has become a standard of care for patients with coronary atherosclerotic disease. While most attention has focused on pre-interventional physiologic assessment to aid in revascularization decision-making, post-interventional physiologic assessment has not been as widely used, despite evidence supporting its role in assessment and optimization of the revascularization procedure. A thorough understanding of such evidence and ongoing studies would be crucial to incorporate post-interventional physiologic assessment into daily practice. Thus, this review provides a comprehensive overview of current evidence regarding the evolving role of physiologic assessment as a functional optimization tool for the entire revascularization process.

Coronary Physiology as Part of a State-of-the-Art Percutaneous Coronary Intervention Strategy: Lessons from SYNTAX II and Beyond

The use of coronary physiology allows for rational decision making at the time of PCI, contributing to better patient outcomes. Yet, coronary physiology is only one aspect of optimal revascularization. State-of-the-art PCI must also consider other important aspects such as intracoronary imaging guidance and specific procedural expertise, as tested in the SYNTAX II study. In this review, we highlight the technical aspects pertaining to the use of physiology as used in that trial and offer a glimpse into the future with emerging physiologic metrics, including functional coronary angiography, which have already established themselves as useful indices to guide decision making.

Intravascular Ultrasound Guidance Is Associated with a Favorable One-Year Target Vessel Failure Rate and No Residual Myocardial Ischemia after the Percutaneous Treatment of Very Long Coronary Artery Lesions

Background: Studies have shown that percutaneous coronary intervention (PCI) in long coronary artery lesions (≥30 mm) is associated with more frequent target vessel failure (TVF), and a significant proportion of patients have lesions that continue to induce ischemia after PCI (FFR ≤ 0.8). We investigated the impact of intravascular ultrasound (IVUS) on the functional PCI result and one-year TVF rate after the percutaneous treatment of long coronary artery lesions. Methods: A total of 80 patients underwent IVUS-guided PCI in long coronary artery lesions. The PCI results were validated with IVUS and FFR. Procedural outcomes were the proportion of patients with: (1) optimal physiology result (post PCI FFR value ≥ 0.9); (2) optimal anatomy result (all IVUS PCI optimization criteria met); and (3) optimal physiology and anatomy result. The clinical outcome was TVF during a one-year follow-up (target vessel (TV)-related death, TV myocardial infarction, ischemia-driven TV revascularization). Results: The mean stented segment length was 62 mm. The target vessel (TV) was the left anterior descending artery in 82.5% of cases. There were no patients with residual ischemia (FFR ≤ 0.8) after PCI. Optimal coronary flow (FFR ≥ 0.9) was achieved in 37.5%; optimal anatomy, as assessed by IVUS, was achieved in 68.4%; and both optimal flow and anatomy were achieved in 25% of patients. Target vessel failure during the 12-month follow-up was 2.5%. Conclusions: In the percutaneous treatment of very long coronary artery lesions, the use of IVUS guidance is associated with a low TVF rate during a one-year follow-up and no residual myocardial ischemia, as assessed by FFR.

Immediate post-procedural functional assessment of percutaneous coronary intervention: current evidence and future directions

Percutaneous coronary intervention (PCI) guided by coronary physiology provides symptomatic benefit and improves patient outcomes. Nevertheless, over one-fourth of patients still experience recurrent angina or major adverse cardiac events following the index procedure. Coronary angiography, the current workhorse for evaluating PCI efficacy, has limited ability to identify suboptimal PCI results. Accumulating evidence supports the usefulness of immediate post-procedural functional assessment. This review discusses the incidence and possible mechanisms behind a suboptimal physiology immediately after PCI. Furthermore, we summarize the current evidence base supporting the usefulness of immediate post-PCI functional assessment for evaluating PCI effectiveness, guiding PCI optimization, and predicting clinical outcomes. Multiple observational studies and post hoc analyses of datasets from randomized trials demonstrated that higher post-PCI functional results are associated with better clinical outcomes as well as a reduced rate of residual angina and repeat revascularization. As such, post-PCI functional assessment is anticipated to impact patient management, secondary prevention, and resource utilization. Pre-PCI physiological guidance has been shown to improve clinical outcomes and reduce health care costs. Whether similar benefits can be achieved using post-PCI physiological assessment requires evaluation in randomized clinical outcome trials.

Physiology-Based Revascularization: A New Approach to Plan and Optimize Percutaneous Coronary Intervention

Coronary physiological assessment using fractional flow reserve or nonhyperemic pressure ratios has become a standard of care for patients with coronary atherosclerotic disease. However, most evidence has focused on the pre-interventional use of physiological assessment to aid revascularization decision-making, whereas post-interventional physiological assessment has not been well established. Although evidence for supporting the role of post-interventional physiological assessment to optimize immediate revascularization results and long-term prognosis has been reported, a more thorough understanding of these data is crucial in incorporating post-interventional physiological assessment into daily practice. Recent scientific efforts have also focused on the potential role of pre-interventional fractional flow reserve or nonhyperemic pressure ratio pullback tracings to characterize patterns of coronary atherosclerotic disease to better predict post-interventional physiological outcomes, and thereby identify the appropriate revascularization target. Pre-interventional pullback tracings with dedicated post-processing methods can provide characterization of focal versus diffuse disease or major gradient versus minor gradient stenosis, which would result in different post-interventional physiological results. This review provides a comprehensive look at the current evidence regarding the evolving role of physiological assessment as a functional optimization tool for the entire process of revascularization, and not merely as a pre-interventional tool for revascularization decision-making.

Fractional Flow Reserve following Percutaneous Coronary Intervention

Fractional flow reserve (FFR) is routinely used to determine lesion severity prior to percutaneous coronary intervention (PCI). However, there is an increasing recognition that FFR may also be useful following PCI to identify mechanisms leading to restenosis and the need for repeat revascularization. Post-PCI FFR is associated with the presence and severity of stent under-expansion and may help identify peri-stent-related complications. FFR pullback may also unmask other functionally significant lesions within the target vessel that were not appreciable on angiography. Recent studies have confirmed the prognostic utility of performing routine post-PCI FFR and suggest possible interventional targets that would improve stent durability. In this review, we detail the theoretical basis underlying post-PCI FFR, provide practical tips to facilitate measurement, and discuss the growing evidence supporting its use.

A randomized controlled trial of a physiology-guided percutaneous coronary intervention optimization strategy: Rationale and design of the TARGET FFR study

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) ≥0.90 confers an improved cardiac prognosis. There are currently limited data available to determine how often it is possible to improve an angiographically acceptable but physiologically suboptimal result. A physiology-guided optimization strategy can achieve a clinically meaningful increase in the proportion of patients achieving a final post-PCI FFR ≥0.90 compared to standard care. Following angiographically successful PCI procedures, 260 patients will be randomized (1:1) to receive either a physiology-guided incremental optimization strategy (intervention group) or blinded post-PCI coronary physiology measurements (control group). Patients undergoing successful, standard-of-care PCI for either stable angina or non-ST-segment-elevation myocardial infarction who meet the study's inclusion and exclusion criteria will be eligible for randomization. The primary endpoint is defined as the proportion of patients with a final post-PCI FFR result ≥0.90. Secondary endpoints include change from baseline in Seattle Angina Questionnaire and EQ-5D-5L scores at 3 months and the rate of target vessel failure and its components (cardiac death, myocardial infarction, stent thrombosis, unplanned rehospitalization with target vessel revascularization) at 3 months and 1 year. 260 individual patients were successfully randomized between March 2018 and November 2019. Key baseline demographics of the study population are reported within. TARGET FFR is an investigator-initiated, prospective, single-center, randomized controlled trial of an FFR-guided PCI optimization strategy. The study has completed recruitment and is now in clinical follow-up. It is anticipated that primary results will be presented in Autumn 2020. ClinicalTrials.gov Identifier: NCT03259815. [Correction added on Apr 3 2020, after first online publication: Clinical Trials identifier added.].

Personalised fractional flow reserve: a novel concept to optimise myocardial revascularisation

AIMS

Fractional flow reserve (FFR) represents the percentage reduction in coronary flow relative to a hypothetically normal artery; however, percutaneous coronary intervention (PCI) seldom achieves physiological normality (FFR 1.00), particularly in the context of diffuse disease. In this study we describe a method for calculating the vessel-specific maximal achievable FFR (FFRmax) providing a personalised assessment of what PCI can achieve.

METHODS AND RESULTS

FFR measurements were obtained from 71 patients (100 arteries) undergoing angiography. Three-dimensional (3D) coronary anatomy was reconstructed from angiographic images. An ideal intervention, in which all stenoses are removed, was modelled, and the FFRmax calculated. The "personalised" FFR (FFRpers) was calculated as measured FFR/FFRmax. PCI was performed in 52 vessels and post-PCI FFR measured in 50. FFRmax was compared to post-PCI measured FFRs. The mean FFRmax was 0.92 (±0.04). This was on average 0.04 (±0.05) higher than the corresponding post-PCI measured FFR (p<0.001). FFRpers was significantly higher (0.06±0.04) than measured FFR (p<0.001), indicating that FFR overestimates flow restoration achievable with PCI.

CONCLUSIONS

A patient's maximal achievable FFR can now be determined prior to PCI. This approach provides a more realistic assessment of the physiological benefit of PCI than is implied by baseline FFR and may prevent unnecessary intervention.

Paclitaxel-Coated Balloon Angioplasty Versus Drug-Eluting Stent in Acute Myocardial Infarction: The REVELATION Randomized Trial

OBJECTIVES

This study sought to assess the efficacy and safety of a drug-coated balloon (DCB) strategy versus drug-eluting stent (DES) in primary percutaneous coronary intervention for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

In primary percutaneous coronary intervention for STEMI, stenting has proved to be beneficial with regard to repeat revascularization, but not recurrent myocardial infarction or death, compared with balloon angioplasty alone. A strategy of DCB angioplasty without stenting might abolish the potential disadvantages of stent implantation while reducing the probability of restenosis observed in plain old balloon angioplasty.

METHODS

In the prospective, randomized, single-center REVELATION trial, we compared DCB with DES in patients presenting with STEMI. Patients with a new, nonseverely calcified culprit lesion in a native coronary artery and a residual stenosis of <50% after pre-dilatation were randomized to treatment with a DCB or DES. The primary endpoint was fractional flow reserve at 9 months, allowing for a functional measurement of the infarct-related lesion.

RESULTS

A total of 120 patients were included. At 9 months after enrolment, the mean fractional flow reserve value was 0.92 ± 0.05 in the DCB group (n = 35) and 0.91 ± 0.06 in the DES group (n = 38) (p = 0.27). One abrupt vessel closure requiring treatment occurred after treatment with DCB. Up to 9-months follow-up, 2 patients required nonurgent target lesion revascularization (1 in each group).

CONCLUSIONS

In the setting of STEMI, the DCB strategy was noninferior to DES in terms of fractional flow reserve assessed at 9 months. Furthermore, it seemed to be a safe and feasible strategy. (Revascularization With Paclitaxel-Coated Balloon Angioplasty Versus Drug-Eluting Stenting in Acute Myocardial Infarction [REVELATION]; NCT02219802).

Novel predictor of target vessel revascularization after coronary stent implantation: Intraluminal intensity of blood speckle on intravascular ultrasound

BACKGROUND

The difference in intraluminal intensity of blood speckle (IBS) on integrated backscatter-intravascular ultrasound (IB-IVUS) across the coronary artery stenosis (i.e., ΔIBS) has been reported to negatively correlate with fractional flow reserve. Fractional flow reserve after coronary stenting is known as a predictor of target vessel revascularization (TVR). However, the relation between ΔIBS and TVR is unclear.

METHODS

Seven hundred and three vessels which underwent percutaneous coronary intervention with stents were screened. Vessels without IVUS-guidance and follow-up information were excluded. Intraluminal IBS values were measured using IB-IVUS in cross-sections at the ostium of the target vessel and at the distal reference of implanted stent. ΔIBS was calculated as (distal IBS) - (ostium IBS).

RESULTS

A total of 393 vessels were included. Mean ΔIBS at postprocedure was 6.22 ± 5.65. During the follow-up period (11.2 ± 3.1 months), 24 cases (6.1%) had TVR. ΔIBS was significantly greater in the vessels with TVR than in those without (11.10 ± 5.93 vs. 5.90 ± 5.49, P <0.001). In receiver operating characteristic curve analysis, ΔIBS significantly predicted TVR (AUC 0.74, best cut-off value 8.24, P < 0.001). Multiple logistic regression analysis showed use of drug eluting stent and ΔIBS ≥ 8.24 as independent predictors of TVR.

CONCLUSIONS

ΔIBS at postprocedure was significantly associated with TVR. IVUS may be able to predict TVR by physiological assessment with measurement of ΔIBS.

Clinical and angiographic predictors of persistently ischemic fractional flow reserve after percutaneous revascularization

AIMS

Despite optimal angiographic results after percutaneous coronary intervention (PCI), some lesions may continue to produce ischemia under maximal hyperemia. We evaluated the factors associated with persistently ischemic fractional flow reserve (FFR) after angiographically successful PCI.

METHODS AND RESULTS

A total of 574 consecutive patients with 664 lesions undergoing PCI who had FFR pre- and post-PCI were analyzed. Percutaneous coronary intervention led to effective ischemia reduction from pre-FFR (0.65±0.14) to post-FFR (0.87±0.08; ∆FFR 0.22±0.16, P<.001). There were 63 (9.5%) lesions with a persistently ischemic FFR of ≤0.80 despite optimal angiographic PCI results. Multivariate analysis revealed the presence of diffuse disease (odds ratio [OR] 3.54, 95% CI 1.80-6.94, P<.01), left anterior descending artery PCI (OR 8.35, 95% CI 3.82-18.27, P<.01), use of intravenous adenosine for inducing hyperemia (OR 3.95, 95% CI 2.0-7.84, P<.01), and pre-PCI FFR (OR 0.03, 95% CI 0.004-0.23, P<.01) as independent predictors of persistently ischemic FFR (≤0.80) after PCI. The predictive accuracy of this model was robust, with an area under the curve of 0.85 (95% CI 0.82-0.88).

CONCLUSION

Multiple factors are associated with persistently ischemic FFR after angiographically optimal PCI. It is recommended that in lesions with the above-identified factors, FFR should be remeasured after PCI, and if abnormal, further measures should be undertaken for functional optimization.

Visualization of the improvement of myocardial perfusion after coronary intervention using motorized fractional flow reserve pullback curve

This study aimed to evaluate the feasibility and utility of using motorized pullback of the pressure guidewire to provide a graphic assessment and prediction of the benefits of coronary intervention. Fractional flow reserve (FFR) measurements were performed with motorized pullback imaging in 20 patients who underwent successful percutaneous coronary intervention (PCI) of the left anterior descending artery. Physiological lesion length (PLL) was calculated using frame counts to determine stent length. FFR area was calculated by integrating the FFR values recorded during pullback tracing (FFRarea). The percentage increase in FFR area (%FFRarea) was defined as the ratio of the difference between the pre- and post-intervention FFRarea to the total frame count. The average FFR values were enhanced following PCI, from 0.64 to 0.82, and the median value of the difference between pre- and post-interventional FFR values (D-FFR) and %FFRarea were 0.13 and 10.6%, respectively. The %FFRarea demonstrated a significant positive correlation with D-FFR (R², 0.61; p < 0.01). PLL tended to be longer and the %FFRarea was smaller in lesions with a gradual pressure-drop pattern than those with an abrupt pressure-drop pattern (35.37 vs. 20.40 mm, p = 0.07; 5.78 vs. 16.21%, p < 0.05, respectively). Motorized pullback tracing was able to identify the extent and location of stenosis and help in appropriate stent implantation, in addition to visualizing and quantifying the improvement in FFR following PCI.

Impact of lesion characteristics on the prediction of optimal poststent fractional flow reserve

BACKGROUND

Poststent fractional flow reserve (FFR) is a useful indicator of optimal percutaneous coronary intervention, and higher poststent FFR is associated with favorable long-term clinical outcome. However, little is known about the factors influencing poststent FFR. The purpose of this study was to determine the impact of lesion characteristics on poststent FFR.

METHODS

For patients who had scheduled stent implantation for stable angina, FFR measurements at maximum hyperemia were performed before and after coronary stent implantation. As one of lesion characteristics, the FFR pressure drop pattern was evaluated and classified as either an abrupt or a gradual pattern according to the pullback curve of FFR.

RESULTS

A total of 205 lesions with physiological significant stenosis were evaluated. Fractional flow reserve value increased from 0.67±0.10 to 0.87±0.07 after stent implantation. Optimal poststent FFR was achieved in 75 lesions (36.6%). Logistic regression analysis demonstrated that optimal poststent FFR was positively correlated with an abrupt pressure drop pattern (hazard ratio [HR] 2.11, 95% CI 1.06-4.15, P=.03) and prestent FFR (HR 1.04, 95% CI 1.03-2.04, P=.03; per 0.1 increase), and negatively correlated with lesion localization to the left anterior descending artery (HR 0.18, 95% CI 0.09-0.36, P<.0001). The c statistic for predicting optimal poststent FFR was 0.763 (95% CI 0.702-0.819).

CONCLUSION

Abrupt pressure drop patterns, prestent FFR, and lesion localization to the left anterior descending artery were independent predictors of optimal poststent FFR.

Ability of Fractional Flow Reserve to Predict Restenosis After Superficial Femoral Artery Stenting

PURPOSE

To evaluate the clinical efficacy of poststenting fractional flow reserve (FFR) in terms of predicting restenosis in superficial femoral artery (SFA) disease.

METHODS

This prospective, single-center, nonrandomized study enrolled 48 patients (mean age 76±9 years; 38 men) with 51 SFA lesions from July 2013 to June 2014. Mean FFR (distal mean pressure/proximal mean pressure) and systolic FFR (distal systolic pressure/proximal systolic pressure) were calculated, and the relationship between these FFR values and restenosis at 12 months was investigated using receiver operating characteristic (ROC) curve analysis.

RESULTS

Poststenting FFR was significantly lower in the restenosis group (poststenting mean FFR 0.85±0.07 vs 0.93±0.05, p=0.001; poststenting systolic FFR 0.76±0.14 vs 0.87±0.08, p=0.015). The area under the ROC curve for restenosis in poststenting mean FFR was higher, but not statistically significant, than that in poststenting systolic FFR (0.84 vs 0.74, p=0.08). The best poststenting mean FFR cutoff value for predicting restenosis was 0.92 (sensitivity 0.64, specificity 0.91). The 4.5% restenosis rate at 12 months in the high (>0.92) poststenting mean FFR group was significantly lower (35.7%, p=0.008) than in the low (≤0.92) poststenting mean FFR group.

CONCLUSION

Poststenting mean FFR is useful for predicting restenosis in SFA disease.

Invasive and non-invasive fractional flow reserve index in validation of hemodynamic severity of intracoronary lesions

This review discusses visual and functional evaluation of the hemodynamic significance of the degree of stenosis in coronary angiography, with respect to the indications for revascularization. The concept of the coronary flow reserve is defined, and the theoretical assumptions of the invasive measurement of the fractional flow reserve (FFR) are presented. In the following part, the publication describes the basic steps of numerical stimulations in terms of computational fluid dynamics (CFD) in calculating the fractional flow reserve based on computed tomography (CT) coronary angiography (FFRCT). The numerical FFRCT estimation in correlation with invasive measurements, as well as benefits deriving from FFRCT in the diagnosis of coronary artery disease, is presented in the example of the multicentre prospective DISCOVER-FLOW trial and the DeFACTO project. The CDF method enables to obtain hemodynamic significance of stenosis solely from the coronary anatomy vizualized by CT angiography. The calculation of FFRCT increases the diagnostic reliability of coronary flow reserve estimations. It contributes to the improvement in patients' qualification for contrast coronarography. If the accuracy of FFRCT is confirmed in clinical practice, and the time required for computational processing is shortened, it may turn out that the algorithms of coronary heart disease diagnosis will be verified and it will be to a greater extent based on the CT results.

Utility of myocardial fractional flow reserve for prediction of restenosis following sirolimus-eluting stent implantation

Drug-eluting stents reduce restenosis due to neointimal growth suppression. Considering long-term outcomes, it is both difficult and important to predict drug-eluting stent restenosis. Thus, this study was designed to examine the utility of myocardial fractional flow reserve (FFR) as a predictor of sirolimus-eluting stent (SES) restenosis. Thirty-three patients (35 lesions) were enrolled. Upon completion of SES implantation, FFR was obtained under hyperemia. At 8 months of follow-up, coronary angiography revealed that five lesions had restenosis. Percent diameter stenosis (restenosis 68.7 ± 12.8% vs. non-restenosis 68.7 ± 12.4%, p = 0.78) and lesion length (restenosis 15.8 ± 9.4 mm vs. non-restenosis 14.4 ± 9.2 mm, p = 0.60) were similar. At post-intervention, percent diameter stenosis (restenosis 16.4 ± 6.1% vs. non-restenosis 14.0 ± 7.4%, p = 0.48) and minimum stent area (restenosis 6.01 ± 1.08 mm2 vs. non-restenosis 6.27 ± 1.85 mm2, p = 0.92) were also equivalent. However, proximal edge lumen area was smaller (restenosis 4.24 ± 1.40 mm2 vs. non-restenosis 7.73 ± 2.64 mm2, p = 0.004) and FFR was lower in the restenosis group (restenosis 0.81 ± 0.12 vs. non-restenosis 0.92 ± 0.06, p = 0.029). SES patients with restenosis had a lower FFR post stent deployment, suggesting the decreased FFR may be a useful predictor for SES restenosis.

Coronary pressure measurement based decision making for percutaneous coronary intervention

The fractional flow reserve (FFR) is a simple, reliable, and reproducible physiologic index of lesion severity. In patients with intermediate stenosis, FFR≥0.75 can be used to safely defer percutaneous coronary intervention (PCI), and patients with FFR≥0.75 have a very low cardiac event rate. Coronary pressure measurement can determine which lesion should be treated with PCI in patients with tandem lesions, and PCI on the basis of FFR has been demonstrated to result in an acceptably low repeat PCI rate. FFR can identify patients with equivocal left main coronary artery disease who benefit from coronary bypass surgery. Coronary pressure measurement distinguishes patients with an abrupt pressure drop pattern from those with a gradual pressure drop pattern, and the former group of patients benefit from PCI. Coronary pressure measurement is clinically useful in evaluating sufficient recruitable coronary collateral blood flow for prevention of ischemia, which affects future cardiac events. FFR is useful for the prediction of restenosis after PCI. As an end-point of PCI, FFR ≥0.95 and ≥0.90 would be appropriate for coronary stenting and coronary angioplasty, respectively. In summary, if you encounter a coronary stenosis in doubt you should measure pressure rather than dilate it.

The effect of drug eluting stents on cardiovascular events in patients with intermediate lesions and borderline fractional flow reserve

OBJECTIVE

To assess the role of fractional flow reserve (FFR) in guiding therapy in the drug eluting stent (DES) era.

BACKGROUND

FFR is a useful index for evaluation of the physiological significance of angiographically indeterminate coronary artery lesions. However, its role in the DES era is unknown.

METHODS

Long term outcome of 281 patients with angiographically indeterminate coronary lesions and borderline FFR (0.75 </= FFR < 0.9) was obtained. The outcome of patients who had a DES placed (n = 58), was compared with that of consecutive patients with borderline FFR that were treated by PCI with bare metal stents (BMS, n = 58), or were deferred from revascularization (n = 165).

RESULTS

FFR was significantly higher in the deferred group (median and IQR); 0.85 (0.82 to 0.88) compared with the BMS (0.78; 0.76 to 0.82) and the DES (0.79; 0.77 to 0.82), P < 0.001. Pretreatment FFR was a significant determinant of long term event rates in the deferred patients (P = 0.002) but had no effect in patients treated by PCI. In the deferred group, there were fewer events (death, myocardial infarction, target vessel revascularization) compared with the BMS group; but no significant difference was observed between the DES and the deferred groups.

CONCLUSIONS

In borderline FFR, long term outcome after PCI with BMS is inferior to conservative therapy or PCI with DES. While conservative management is preferable in these patients, PCI with DES may be considered in specific circumstances.

Influence of a Pressure Gradient Distal to Implanted Bare-Metal Stent on In-Stent Restenosis After Percutaneous Coronary Intervention

Background— Fractional flow reserve predicts cardiac events after coronary stent implantation. The aim of the present study was to assess the 9-month angiographic in-stent restenosis rate in the setting of optimal stenting and a persisting gradient distal to the stent as assessed by a pressure wire pullback recording in the entire length of the artery.

Methods and Results— In 98 patients with angina pectoris, 1 de novo coronary lesion was treated with a bare-metal stent. After stent implantation, pressure wire measurements (P d =mean hyperemic coronary pressure and P a =mean aortic pressure) were performed in the target vessel: (1) P d /P a as distal to the artery as possible (fractional flow reserve per definition); (2) P d /P a just distal to the stent; (3) P d /P a just proximal to the stent; and (4) P d /P a at the ostium. Residual abnormal P d /P a was defined as a pressure drop between P d /P a measured at points 1 and 2. Fractional flow reserve distal to the artery after stenting was significantly lower (0.88±0.21 versus 0.97±0.05; P <0.001), and angiographic in-stent binary restenosis rate was significantly higher (44.0% versus 8.1%; P <0.001) in vessels with a residual abnormal P d /P a . Residual abnormal P d /P a (odds ratio, 4.39; 95% confidence interval, 1.10 to 18.16; P =0.034), reference vessel size (odds ratio, 0.17; 95% confidence interval, 0.04 to 0.69; P =0.013), and stent length (odds ratio, 1.11; 95% confidence interval, 1.03 to 1.21; P =0.009) were predictors of angiographic in-stent restenosis after 9 months.

Conclusions— A residual abnormal P d /P a distal to a bare-metal stent was an independent predictor of in-stent restenosis after implantation of a coronary bare-metal stent.