Pre-PCI CT-FFR Predicts Target Vessel Failure After Stent Implantation

OBJECTIVES

To investigate the predictive value of coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) before percutaneous coronary intervention (PCI) to predict target vessel failure (TVF) after stent implantation.

METHODS

This retrospective study included 429 patients (429 vessels) who underwent PCI and stent implantation after CCTA within 3 months. All patients underwent coronary stent implantation between January 2012 and December 2019. A dedicated workstation (Syngo Via, Siemens) was used to analyze and measure the CT-FFR value. The cut-off values of pre-PCI CT-FFR for predicting TVF were defined as 0.80 and the value using the log-rank maximization method, respectively. The primary outcome was TVF, defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target vessel revascularization (TVR), which was a secondary outcome.

RESULTS

During a median 64.0 months follow-up, the cumulative incidence of TVF was 7.9% (34/429). The cutoff value of pre-PCI CT-FFR based on the log-rank maximization method was 0.74, which was the independent predictor for TVF [hazard ratio (HR): 2.61 (95% CI: 1.13, 6.02); P =0.024] and TVR [HR: 3.63 (95%CI: 1.25, 10.51); P =0.018]. Compared with the clinical risk factor model, pre-PCI CT-FFR significantly improved the reclassification ability for TVF [net reclassification improvement (NRI), 0.424, P <0.001; integrative discrimination index (IDI), 0.011, P =0.022]. Adding stent information to the prediction model resulted in an improvement in reclassification for the TVF (C statistics: 0.711, P =0.001; NRI: 0.494, P <0.001; IDI: 0.020, P =0.028).

CONCLUSIONS

Pre-PCI CT-FFR ≤0.74 was an independent predictor for TVF or TVR, and integration of clinical, pre-PCI CT-FFR, and stent information models can provide a better risk stratification model in patients with stent implantation.

Angiographic Findings and Post-Percutaneous Coronary Intervention Fractional Flow Reserve

Importance

The associations between angiographic findings and post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) and their clinical relevance according to residual functional disease burden have not been thoroughly investigated.

Objectives

To evaluate the association of angiographic and physiologic parameters according to residual functional disease burden after drug-eluting stent implantation.

Design, Setting, and Participants

This cohort study population was from the International Post-PCI FFR registry, which incorporated 4 registries from Korea, China, and Japan. Patients who underwent angiographically successful second-generation drug-eluting stent implantation and post-PCI FFR measurement were included in the analysis. The patients were divided into 3 groups according to the residual disease burden (post-PCI FFR ≤0.80 [residual ischemia], 0.81-0.86 [suboptimal], and >0.86 [optimal]). The data were collected from August 23, 2018, to June 11, 2019, and the current analysis was performed from January 11, 2022, to October 7, 2023.

Exposures

Angiographic parameters and post-PCI FFR.

Main Outcomes and Measures

The primary outcome was target vessel failure (TVF), defined as a composite of cardiac death, target vessel-related myocardial infarction, and target vessel revascularization (TVR) at 2 years.

Results

In this cohort of 2147 patients, the mean (SD) age was 64.3 (10.0) years, and 1644 patients (76.6%) were men. Based on the post-PCI physiologic status, 269 patients (12.5%) had residual ischemia, 551 (25.7%) had suboptimal results, and 1327 (61.8%) had optimal results. Angiographic parameters had poor correlations with post-PCI FFR (r < 0.20). Post-PCI FFR was isolated from all angiographic parameters in the unsupervised hierarchical cluster analysis. Post-PCI FFR was associated with the occurrence of TVF (adjusted hazard ratio [AHR] per post-PCI FFR 0.01 increase, 0.94 [95% CI, 0.92-0.97]; P < .001), but angiographic parameters were not. The residual ischemia group had a significantly higher rate of TVF than the suboptimal group (AHR, 1.75 [95% CI, 1.08-2.83]; P = .02) and the optimal group (AHR, 2.94 [95% CI, 1.82-4.73]; P < .001). The TVR in the residual ischemia group was predominantly associated with TVR in the nonstented segment (14 [53.8%]), unlike the other 2 groups (3 [10.0%] in the suboptimal group and 13 [30.2%] in the optimal group).

Conclusions and Relevance

In this cohort study of the International Post-PCI FFR registry, a low degree of associations were observed between angiographic and physiologic parameters after PCI. Post-PCI FFR, unlike angiographic parameters, was associated with clinical events and the distribution of clinical events. The current study supports the use of post-PCI FFR as a procedural quality metric and further prospective study is warranted.

Impact of Relative Improvement in Quantitative Flow Ratio on Clinical Outcomes After Percutaneous Coronary Intervention - A Subanalysis of the PANDA III Trial

BACKGROUND

The clinical impact of relative improvements in coronary physiology in patients receiving percutaneous coronary intervention (PCI) for coronary artery disease (CAD) remains undetermined.Methods and Results: The quantitative flow ratio (QFR) recovery ratio (QRR) was calculated in 1,424 vessels in the PANDA III trial as (post-PCI QFR-pre-PCI QFR)/(1-pre-PCI QFR). The primary endpoint was the 2-year vessel-oriented composite endpoint (VOCE; a composite of vessel-related cardiac death, vessel-related non-procedural myocardial infarction, and ischemia-driven target vessel revascularization). Study vessels were dichotomously stratified according to the optimal QRR cut-off value. During the 2-year follow-up, 41 (2.9%) VOCEs occurred. Low (<0.86) QRR was associated with significantly higher rates of 2-year VOCEs than high (≥0.86) QRR (6.6% vs. 1.4%; adjusted hazard ratio [aHR] 5.05; 95% confidence interval [CI] 2.53-10.08; P<0.001). Notably, among vessels with satisfactory post-procedural physiological results (post-PCI QFR >0.89), low QRR also conferred an increased risk of 2-year VOCEs (3.7% vs. 1.4%; aHR 3.01; 95% CI 1.30-6.94; P=0.010). Significantly better discriminant and reclassification performance was observed after integrating risk stratification by QRR and post-PCI QFR to clinical risk factors (area under the curve 0.80 vs. 0.71 [P=0.010]; integrated discrimination improvement 0.05 [P<0.001]; net reclassification index 0.64 [P<0.001]).

CONCLUSIONS

Relative improvement of coronary physiology assessed by QRR showed applicability in prognostication. Categorical classification of coronary physiology could provide information for risk stratification of CAD patients.

Illusion of revascularization: does anyone achieve optimal revascularization during percutaneous coronary intervention?

This Perspective article is a form of 'pastiche', inspired by the 1993 review by Lincoff and Topol entitled 'Illusion of reperfusion', and explores how their concept continues to apply to percutaneous revascularization in patients with coronary artery disease and ischaemia. Just as Lincoff and Topol argued that reperfusion of acute myocardial infarction was facing unresolved obstacles that hampered clinical success in 1993, we propose that challenging issues are similarly jeopardizing the potential benefits of stent-based angioplasty today. By analysing the appropriateness and efficacy of percutaneous coronary intervention (PCI), we emphasize the limitations of relying solely on visual angiographic guidance, which frequently leads to inappropriate stenting and overtreatment in up to one-third of patients and the associated increased risk of periprocedural myocardial infarction. The lack of optimal revascularization observed in half of patients undergoing PCI confers risks such as suboptimal physiology after PCI, residual angina and long-term stent-related events, leaving an estimated 76% of patients with an 'illusion of revascularization'. These outcomes highlight the need to refine our diagnostic tools by integrating physiological assessments with targeted intracoronary imaging and emerging strategies, such as co-registration systems and angiography-based computational methods enhanced by artificial intelligence, to achieve optimal revascularization outcomes.

Prognostic Value of Poststenting Fractional Flow Reserve After Imaging-Guided Optimal Stenting

BACKGROUND

Prognostic value of poststenting fractional flow reserve (FFR) remains uncertain in patients undergoing an imaging-guided optimal stenting strategy.

OBJECTIVES

The authors evaluated the prognostic value of poststenting FFR according to the intracoronary imaging-guided lesion preparation, stent sizing, and postdilation (iPSP) strategy to optimize stent outcomes.

METHODS

Poststenting FFR assessment was performed in 1,108 lesions in 1,005 patients from the IRIS-FFR registry. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization at 5 years.

RESULTS

At the index procedure, 326 lesions (29.4%) were treated using all 3 parts of the iPSP strategy. In the overall population, poststenting FFR was significantly associated with the risk of TVF at 5 years (per 0.01 increase of FFR, adjusted HR [aHR]: 0.94; 95% CI: 0.90-0.98; P = 0.004). Significant interaction was detected between poststenting FFR and the iPSP strategy on the risk of TVF at 5 years (P = 0.045 for interaction). In the iPSP group, poststenting FFR was not associated with the risk of TVF at 5 years (per 0.01 increase of FFR, aHR: 1.00; 95% CI: 0.96-1.05; P = 0.95), whereas a significant association between poststenting FFR and TVF at 5 years was observed in the no iPSP group (per 0.01 increase of FFR, aHR: 0.94; 95% CI: 0.90-0.99; P = 0.009).

CONCLUSIONS

Poststenting FFR showed a significant association with cardiac events. However, its prognostic value appeared to be limited after the application of an imaging-guided optimal stenting strategy.

Combined Assessment of Fractional Flow Reserve and Coronary Flow Velocity Reserve after Drug-Eluting Stent Implantation

BACKGROUND

Coronary flow velocity reserve (CFVR) can be measured noninvasively using stress transthoracic Doppler echocardiography (S-TDE). The prognostic significance of S-TDE-derived CFVR after percutaneous coronary intervention (PCI) remains unknown. The aim of this study was to investigate the prognostic value of post-PCI CFVR and its additional efficacy to fractional flow reserve (FFR) in patients undergoing elective PCI.

METHODS

A retrospective study was conducted involving 187 consecutive patients with chronic coronary syndrome who underwent elective PCI guided by FFR for the left anterior descending coronary artery. Pre- and post-PCI wire-based FFR and CFVR assessments of the left anterior descending coronary artery using S-TDE were performed in all patients. The association between post-PCI clinical and physiologic parameters and major adverse cardiac events (MACE), defined as a composite of cardiac death, myocardial infarction, heart failure, and unplanned remote target vessel revascularization, was evaluated.

RESULTS

Three-quarters of patients exhibited CFVR increase after PCI, while all patients showed FFR improvement. During a median follow-up period of 1.5 years, MACE occurred in 21 patients (11.2%). Among clinical demographics, patients with MACE had higher levels of N-terminal pro-brain natriuretic peptide compared with those without MACE (median, 615 pg/mL [interquartile range, 245-1,500 pg/mL] vs 180 pg/mL [interquartile range, 70-559 pg/mL]; P = .010). Post-PCI S-TDE-derived CFVR was lower in patients with MACE, while post-PCI FFR showed a nonsignificant tendency to be lower in patients with MACE. In a multivariable analysis, higher NT-proBNP (adjusted hazard ratio, 1.33; 95% CI, 1.02-1.74; P = .038), post-PCI CFVR ≤ 2.0 (adjusted hazard ratio, 2.93; 95% CI, 1.16-7.40; P = .023), and post-PCI FFR ≤ 0.82 (adjusted hazard ratio, 3.93; 95% CI, 1.52-10.18; P = .005) were independently associated with MACE.

CONCLUSIONS

In patients with chronic coronary syndrome who underwent successful elective PCI for left anterior descending coronary artery, the combined assessment of S-TDE-derived post-PCI CFVR and post-PCI FFR provided a significant association with the occurrence of MACE.

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.

Changes in post-PCI physiology based on anatomical vessel location: a DEFINE PCI substudy

BACKGROUND

Anatomical vessel location affects post-percutaneous coronary intervention (PCI) physiology.

AIMS

We aimed to compare the post-PCI instantaneous wave-free ratio (iFR) in left anterior descending (LAD) versus non-LAD vessels and to identify the factors associated with a suboptimal post-PCI iFR.

METHODS

DEFINE PCI was a multicentre, prospective, observational study in which a blinded post-PCI iFR pullback was used to assess residual ischaemia following angiographically successful PCI.

RESULTS

Pre- and post-PCI iFR recordings of 311 LAD and 195 non-LAD vessels were compared. Though pre-PCI iFR in the LAD vessels (median 0.82 [0.63, 0.86]) were higher compared with those in non-LAD vessels (median 0.72 [0.49, 0.84]; p<0.0001), post-PCI iFR were lower in the LAD vessels (median 0.92 [0.88, 0.94] vs 0.98 [0.95, 1.00]; p<0.0001). The prevalence of a suboptimal post-PCI iFR of <0.95 was higher in the LAD vessels (77.8% vs 22.6%; p<0.0001). While the overall frequency of residual physiological diffuse disease (31.4% vs 38.6%; p=0.26) and residual focal disease in the non-stented segment (49.6% vs 50.0%; p=0.99) were similar in both groups, residual focal disease within the stented segment was more common in LAD versus non-LAD vessels (53.7% vs 27.3%; p=0.0009). Improvement in iFR from pre- to post-PCI was associated with angina relief regardless of vessel location.

CONCLUSIONS

After angiographically successful PCI, post-PCI iFR is lower in the LAD compared with non-LAD vessels, resulting in a higher prevalence of suboptimal post-PCI iFR in LAD vessels. This difference is, in part, due to a greater frequency of a residual focal pressure gradient within the stented segment which may be amenable to more aggressive PCI.

Impact of Post-PCI FFR Stratified by Coronary Artery

BACKGROUND

Low fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) has been associated with adverse clinical outcomes. Hitherto, this assessment has been independent of the epicardial vessel interrogated.

OBJECTIVES

This study sought to assess the predictive capacity of post-PCI FFR for target vessel failure (TVF) stratified by coronary artery.

METHODS

We performed a systematic review and individual patient-level data meta-analysis of randomized clinical trials and observational studies with protocol-recommended post-PCI FFR assessment. The difference in post-PCI FFR between left anterior descending (LAD) and non-LAD arteries was assessed using a random-effect models meta-analysis of mean differences. TVF was defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target vessel revascularization.

RESULTS

Overall, 3,336 vessels (n = 2,760 patients) with post-PCI FFR measurements were included in 9 studies. The weighted mean post-PCI FFR was 0.89 (95% CI: 0.87-0.90) and differed significantly between coronary vessels (LAD = 0.86; 95% CI: 0.85 to 0.88 vs non-LAD = 0.93; 95% CI: 0.91-0.94; P < 0.001). Post-PCI FFR was an independent predictor of TVF, with its risk increasing by 52% for every reduction of 0.10 FFR units, and this was mainly driven by TVR. The predictive capacity for TVF was poor for LAD arteries (AUC: 0.52; 95% CI: 0.47-0.58) and moderate for non-LAD arteries (AUC: 0.66; 95% CI: 0.59-0.73; LAD vs non-LAD arteries, P = 0.005).

CONCLUSIONS

The LAD is associated with a lower post-PCI FFR than non-LAD arteries, emphasizing the importance of interpreting post-PCI FFR on a vessel-specific basis. Although a higher post-PCI FFR was associated with improved prognosis, its predictive capacity for events differs between the LAD and non-LAD arteries, being poor in the LAD and moderate in the non-LAD vessels.

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.

Fractional flow reserve and non-hyperemic indices: Essential tools for percutaneous coronary interventions

Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact. Fractional flow reserve (FFR) received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis. FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy, deferring unnecessary procedures for lesions with a FFR > 0.8, improving patients' management and clinical outcome. Post intervention, an optimal FFR > 0.9 post stenting should be reached and > 0.8 post drug eluting balloons. Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89. They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated. FFR remains the gold standard reference for invasive assessment of ischemia. We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio. We conclude introducing a hybrid approach to intermediate lesions (DFR 0.85-0.95) potentially maximizing clinical decision from all measurements.

Clinical Implications of Fractional Flow Reserve Measured Immediately After Percutaneous Coronary Intervention

PURPOSE

The purpose of the present study was to find the independent predictors of Fractional Flow Reserve (FFR) measured immediately after percutaneous coronary intervention with drug-eluting stent implantation (post-PCI FFR) and investigate if applying vessel-specific post-PCI FFR cut-off values to predict target vessel failure (TVF), a composite of cardiac death (CD), non-fatal myocardial infarction (MI) and target vessel revascularization (TVR), or a composite of CD and MI ameliorated its predictive power.

METHODS

Consecutive patients with post-PCI FFR measurement at our center between 2009 and 2021 were included in this analysis.

RESULTS

A total of 434 patients with 500 vessels were included. Median pre-PCI FFR was 0.72 with no difference between LAD and non-LAD vessels. Median post-PCI FFR was 0.87. LAD location, male gender, smaller stent diameter, and lower pre-PCI FFR proved to be significant predictors of a lower post-PCI FFR. On a vessel-level, post-PCI FFR, stent length, and diabetes mellitus proved to be significant predictors of TVF and the composite of CD and MI. The best post-PCI FFR cut-off to predict TVF or a composite of CD and MI was 0.83 in the LAD and 0.91 in non-LAD vessels.

CONCLUSION

LAD location is a predictor of a lower post-PCI FFR. Post-PCI FFR is an independent predictor of TVF as well as of the composite of CD and MI. No uniform target post-PCI FFR value exists; different cut-off values may have to be applied in LAD as opposed to non-LAD vessels.

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.

Prediction of functional results of percutaneous coronary interventions with virtual stenting and quantitative flow ratio

BACKGROUND

The clinical value of residual quantitative flow ratio (rQFR), a novel function of QFR technique, is unknown.

AIM

We investigated the clinical value of rQFR, aimed to predict residual ischemia after virtual percutaneous coronary intervention (vPCI).

METHODS

This is a substudy of the COE-PERSPECTIVE registry, which investigated the prognostic value of post-PCI fractional flow reserve (FFR). From pre-PCI angiograms, QFR and rQFR were analyzed and their diagnostic performance was assessed at blinded fashion using pre-PCI FFR and post-PCI FFR as reference, respectively. The prognostic value of rQFR after vPCI was assessed according to vessel-oriented composite outcome (VOCO) at 2 years.

RESULTS

We analyzed 274 patients (274 vessels) with FFR-based ischemic causing lesions (49%) from 555 screened patients. Pre-PCI QFR and FFR were 0.63 ± 0.10 and 0.66 ± 0.11 (R = 0.756, p < 0.001). rQFR after vPCI and FFR after real PCI were 0.93 ± 0.06 and 0.86 ± 0.07 (R = 0.528, p < 0.001). The mean difference between rQFR and post-PCI FFR was 0.068 (95% limit of agreement: -0.05 to 0.19). Diagnostic performance of rQFR to predict residual ischemia after PCI was good (area under the curve [AUC]: 0.856 [0.804-0.909], p < 0.001). rQFR predicted well the incidence of 2-year VOCO after index PCI (AUC: 0.712 [0.555-0.869], p = 0.041), being similar to that of actual post-PCI FFR (AUC: 0.691 [0.512-0.870], p = 0.061). rQFR ≤0.89 was associated with increased risk of 2-year VOCO (hazard ratio [HR]: 12.9 [2.32-71.3], p = 0.0035). This difference was mainly driven by a higher rate of target vessel revascularization (HR: 16.98 [2.33-123.29], p = 0.0051).

CONCLUSIONS

rQFR estimated from pre-PCI angiography and virtual coronary stenting mildly overestimated functional benefit of PCI. However, it well predicted suboptimal functional result and long-term vessel-related clinical events.

CLINICAL TRIAL REGISTRATION

Influence of fractional flow reserve on the Clinical OutcomEs of PERcutaneouS Coronary Intervention (COE-PESPECTIVE) Registry, NCT01873560.

Diagnostic accuracy of angiography‐based vessel fractional flow reserve after chronic coronary total occlusion recanalization

BACKGROUND

Angiography-based vessel fractional flow reserve (vFFR) demonstrated a strong correlation with invasive fractional flow reserve (FFR) in both a pre- and post-percutaneous coronary intervention (PCI) setting. However, the role of vFFR and its correlation with post-PCI FFR in chronic coronary occlusions (CTO) has not been evaluated yet. We sought to investigate the diagnostic performance of post-PCI vFFR with post-PCI FFR as a reference in patients undergoing successful CTO PCI.

METHODS

Between March 2016 and April 2020, a total of 80 patients from the FFR-SEARCH (prospective registry) and FFR REACT (randomized controlled trial) studies underwent successful CTO recanalization with post-PCI FFR measurements.

RESULTS

A total of 50 patients (median age 66 (interquartile range [IQR]: 56-74) years, 76% were male) were eligible for the analysis. Median post-PCI FFR was 0.89 (IQR: 0.84-0.94), while median post-PCI vFFR was 0.91 (IQR: 0.85-0.94) (p 0.10). Suboptimal physiological results, defined as FFR and vFFR <0.90, were identified in 26 (52%) and in 21 (42%) patients, respectively. A strong correlation (r = 0.82) was found between vFFR and FFR with a mean bias of 0.013 ± 0.051. Receiver-operating characteristics curve analysis revealed an excellent accuracy of vFFR in predicting FFR <0.90 (area under the curve: 0.97; 95% confidence interval: 0.93-1.00).

CONCLUSION

Post-PCI vFFR shows a good correlation with post-PCI FFR and a high diagnostic accuracy for post-PCI FFR ≤0.90 in patients undergoing successful PCI of a CTO lesion.

FFR-Guided PCI Optimization Directed by High-Definition IVUS Versus Standard of Care: The FFR REACT Trial

BACKGROUND

Post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) <0.90 is common and has been related to impaired patient outcome.

OBJECTIVES

The authors sought to evaluate if PCI optimization directed by intravascular ultrasound (IVUS) in patients with post-PCI FFR <0.90 could improve 1-year target vessel failure (TVF) rates.

METHODS

In this single-center, randomized, double-blind trial, patients with a post-PCI FFR <0.90 at the time of angiographically successful PCI were randomized to IVUS-guided optimization or the standard of care (control arm). The primary endpoint was TVF (a composite of cardiac death, spontaneous target vessel myocardial infarction, and clinically driven target vessel revascularization) at 1 year.

RESULTS

A total of 291 patients with post-PCI FFR <0.90 were randomized (IVUS-guided optimization arm: n = 145/152 vessels, control arm: n = 146/157 vessels). The mean post-PCI FFR was 0.84 ± 0.05. A total of 104 (68.4%) vessels in the IVUS-guided optimization arm underwent additional optimization including additional stenting (34.9%) or postdilatation only (33.6%), resulting in a mean increase in post-PCI FFR in these vessels from 0.82 ± 0.06 to 0.85 ± 0.05 (P < 0.001) and a post-PCI FFR ≥0.90 in 20% of the vessels. The 1-year TVF rate was comparable between the 2 study arms (IVUS-guided optimization arm: 4.2%, control arm: 4.8%; P = 0.79). There was a trend toward a lower incidence of clinically driven target vessel revascularization in the IVUS-guided optimization arm (0.7% vs. 4.2%, P = 0.06).

CONCLUSIONS

IVUS-guided post-PCI FFR optimization significantly improved post-PCI FFR. Because of lower-than-expected event rates, post-PCI FFR optimization did not significantly lower TVF at the 1-year follow-up.

Safety and effectiveness of post percutaneous coronary intervention physiological assessment: Retrospective data from the post-revascularization optimization and physiological evaluation of intermediate lesions using fractional flow reserve registry

Background

While the importance of invasive physiological assessment (IPA) to choose coronary lesions to be treated is ascertained, its role after PCI is less established. We evaluated feasibility and efficacy of Physiology-guided PCI in the everyday practice in a retrospective registry performed in a single high-volume and “physiology-believer” center.

Materials and methods

The PROPHET-FFR study (NCT05056662) patients undergoing an IPA in 2015–2020 were retrospectively enrolled in three groups: Control group comprising patients for whom PCI was deferred based on a IPA; Angiography-Guided PCI group comprising patients undergoing PCI based on an IPA but without a post-PCI IPA; Physiology-guided PCI group comprising patients undergoing PCI based on an IPA and an IPA after PCI, followed by a physiology-guided optimization, if indicated. Optimal result was defined by an FFR value ≥ 0.90.

Results

A total of 1,322 patients with 1,591 lesions were available for the analysis. 893 patients (67.5%) in Control Group, 249 patients (18.8%) in Angiography-guided PCI Group and 180 patients (13.6%) in Physiology-guided PCI group. In 89 patients a suboptimal functional result was achieved that was optimized in 22 cases leading to a “Final FFR” value of 0.90 ± 0.04 in Angiography-Guided PCI group. Procedural time, costs, and rate of complications were similar. At follow up the rate of MACEs for the Physiology-guided PCI group was similar to the Control Group (7.2% vs. 8.2%, p = 0.765) and significantly lower than the Angiography-guided PCI Group (14.9%, p < 0.001), mainly driven by a reduction in TVRs.

Conclusion

“Physiology-guided PCI” is a feasible strategy with a favorable impact on mid-term prognosis. Prospective studies using a standardized IPA are warrant to confirm these data.

Angiography-Based Fractional Flow Reserve: State of the Art

Purpose of Review

Three-dimensional quantitative coronary angiography-based methods of fractional flow reserve (FFR) derivation have emerged as an appealing alternative to conventional pressure-wire-based physiological lesion assessment and have the potential to further extend the use of physiology in general. Here, we summarize the current evidence related to angiography-based FFR and perspectives on future developments.

Recent Findings

Growing evidence suggests good diagnostic performance of angiography-based FFR measurements, both in chronic and acute coronary syndromes, as well as in specific lesion subsets, such as long and calcified lesions, left main coronary stenosis, and bifurcations. More recently, promising results on the superiority of angiography-based FFR as compared to angiography-guided PCI have been published.

Summary

Currently available angiography -FFR indices proved to be an excellent alternative to invasive pressure wire-based FFR. Dedicated prospective outcome data comparing these indices to routine guideline recommended PCI including the use of FFR are eagerly awaited.

The prognostic value of angiography-based vessel fractional flow reserve after percutaneous coronary intervention: The FAST Outcome study

BACKGROUND

Vessel Fractional Flow Reserve (vFFR) as assessed by three-dimensional quantitative coronary angiography has high correlation with pressure wire-based fractional flow reserve in both a pre- and post-PCI setting. The present study aims to assess the prognostic value of post-PCI vFFR on the incidence of target vessel failure (TVF), a composite endpoint of cardiac death, target vessel myocardial infarction and target vessel revascularization (TVR) at 5-year follow up.

METHODS

Post-PCI vFFR was calculated after routine PCI in a total of 748 patients (832 vessels) with available orthogonal angiographic projections of the stented segment.

RESULTS

Median age was 65 (IQR 55-74) years, 18.2% were diabetic, and 29.1% presented with stable angina. Median post-PCI vFFR was 0.91 (IQR 0.86-0.95). Vessels were categorized into tertiles based on post-PCI vFFR: low (vFFR <0.88), middle (vFFR 0.88-0.93), and upper (vFFR ≥0.94). Vessels in the lower and middle tertile were more often LADs and had smaller stent diameters (p-value <0.001). Vessels in the lower and middle tertile had a higher risk of TVF as compared to vessels in the upper tertile (24.6% and 21.5% vs. 17.1%; adjusted HR 1.84 (95%CI 1.15-2.95), p = 0.011, and 1.58 (95%CI 1.02-2.45), p = 0.040) at 5-years follow-up. Additionally, vessels in the lower tertile had higher rates of TVR as compared to vessels in the higher tertile (12.6% vs. 6.5%, adjusted HR 1.93 (95%CI 1.06-3.53), p-value = 0.033).

CONCLUSION

Lower post-PCI vFFR values are associated with a significantly increased risk of TVF and TVR at 5-years follow-up.

Diagnostic Accuracy of Coronary Angiography-Based Vessel Fractional Flow Reserve (vFFR) Virtual Stenting

3D coronary angiography-based vessel fractional flow reserve (vFFR) proved to be an accurate diagnostic alternative to invasively measured pressure wire based fractional flow reserve (FFR). The ability to compute post-PCI vFFR using pre-PCI vFFR virtual stent analysis is unknown. We aimed to assess the feasibility and diagnostic accuracy of pre-PCI vFFR virtual stenting analysis (residual vFFR) with post-PCI FFR as a reference. This is an observational, single-center retrospective cohort study including consecutive patients from the FFR-SEARCH registry. We blindly calculated residual vFFR from pre-PCI angiograms and compared them to invasive pressure-wire based post-PCI FFR. Inclusion criteria involved presentation with either stable or unstable angina or non-ST elevation myocardial infarction (NSTEMI), ≥1 significant stenosis in one of the epicardial coronary arteries (percentage diameter stenosis of >70% by QCA or hemodynamically relevant stenosis with FFR ≤0.80) and pre procedural angiograms eligible for vFFR analysis. Exclusion criteria comprised patients with ST elevation myocardial infarction (STEMI), coronary bypass grafts, cardiogenic shock or severe hemodynamic instability. Eighty-one pre-PCI residual vFFR measurements were compared to post-PCI FFR and post-PCI vFFR measurements. Mean residual vFFR was 0.91 ± 0.06, mean post-PCI FFR 0.91 ± 0.06 and mean post-PCI vFFR was 0.92 ± 0.05. Residual vFFR showed a high linear correlation (r = 0.84) and good agreement (mean difference (95% confidence interval): 0.005 (−0.002−0.012)) with post-PCI FFR, as well as with post-PCI-vFFR (r = 0.77, mean difference −0.007 (−0.015−0.0003)). Residual vFFR showed good accuracy in the identification of lesions with post-PCI FFR < 0.90 (sensitivity 94%, specificity 71%, area under the curve (AUC) 0.93 (95% CI: 0.86−0.99), p < 0.001). Virtual stenting using vFFR provided an accurate estimation of post-PCI FFR and post-PCI vFFR. Further studies are needed to prospectively validate a vFFR-guided PCI strategy.

Effect of Coronary Disease Characteristics on Prognostic Relevance of Residual Ischemia After Stent Implantation

Objectives: We investigated the influence of coronary disease characteristics on prognostic implications of residual ischemia after coronary stent implantation.

Methods: This study included 1,476 patients with drug-eluting stent implantation and available pre- and post-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) measurements. Residual ischemia was defined as post-PCI FFR ≤ 0.80. Coronary disease characteristics with significant interaction hazard ratios (HRs) for clinical outcomes with residual ischemia were defined as interaction characteristics with residual ischemia (ICwRI). The primary outcome was target vessel failure (TVF)—a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization—at 2 years.

Results: The mean pre- and post-PCI FFR were 0.68 ± 0.11 and 0.87 ± 0.07, respectively. During the median follow-up duration of 2.0 years, the cumulative incidence of TVF was 6.1%. The 203 vessels (13.8%) with residual ischemia had higher risks of TVF compared to that for post-PCI FFR >0.80 (P < 0.001). ICwRI with a significant interaction HR with residual ischemia included pre-PCI SYNTAX score >17 and pre-PCI FFR ≤ 0.62. Each ICwRI had a direct prognostic effect not mediated by residual ischemia. The association between an increased TVF risk and residual ischemia was significant in patients with 0 or 1 ICwRI [hazard ratio (HR) 3.25, 95% confidence interval (CI) 1.90–5.57, P < 0.001] but not in those with 2 ICwRI (HR 0.47, 95% CI 0.14–1.64, P = 0.24). Among patients with post-PCI FFR >0.80, those with 2 ICwRI showed similar TVF risks to those with residual ischemia (HR 1.55, 95% CI 0.79–3.02, P = 0.20).

Conclusions: Coronary disease characteristics including pre-PCI SYNTAX score and pre-PCI FFR affected the prognostic implications of residual ischemia. The prognostic relevance of residual ischemia was attenuated in patients with multiple interacting characteristics.

Improving PCI Outcomes Using Postprocedural Physiology and Intravascular Imaging

Although clinical outcomes after percutaneous coronary intervention (PCI) are improving, the long-term risk for target vessel failure remains concerning. Although the application of intravascular imaging and physiological indexes significantly improves outcomes, their routine use in practice remains limited. Nevertheless, merely using these modalities is not enough, and to truly improve patient outcomes, optimal intravascular dimensions with minimal vascular injury should be targeted. When assessing post-PCI results using either type of physiological or imaging technology, a broad spectrum of stent- and vessel-related anomalies can be expected. As not all of these issues warrant treatment, a profound knowledge of what to expect and how to recognize and when to treat these intraluminal problems is needed. Additionally, promising new modalities such as angiography-derived coronary physiology and hybrid imaging catheters are becoming available. The authors provide an overview of the currently available tools and techniques to define suboptimal PCI and when to apply these technologies to improve outcomes.

Differential Prognostic Implications of Pre- and Post-Stent Fractional Flow Reserve in Patients Undergoing Percutaneous Coronary Intervention

The current study showed that pre-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) was associated with target vessel failure (TVF) after PCI. When the prognostic value of post-PCI FFR was evaluated according to pre-PCI FFR value, the risk of TVF significantly decreased along with the increase of post-PCI FFR in the low pre-PCI FFR group, but not in the high pre-PCI FFR group. Our study results suggest that patient prognosis can be varied according to the level of physiologic indices, both before and after PCI, and the integration of both information can provide better risk stratification after PCI.

Background and Objectives

The influence of pre-intervention coronary physiologic status on outcomes post percutaneous coronary intervention (PCI) is not well known. We sought to investigate the prognostic implications of pre-PCI fractional flow reserve (FFR) combined with post-PCI FFR.

Methods

A total of 1,479 PCI patients with pre-and post-PCI FFR data were analyzed. The patients were classified according to the median values of pre-PCI FFR (0.71) and post-PCI FFR (0.88). The primary outcome was target vessel failure (TVF) at 2 years.

Results

The risk of TVF was higher in the low pre-PCI FFR group than in the high pre-PCI FFR group (hazard ratio, 1.82; 95% confidence interval, 1.15–2.87; p=0.011). In 4 group comparisons, the cumulative incidences of TVF at 2 years were 3.8%, 4.1%, 4.8%, and 10.2% in the high pre-/high post-, low pre-/high post-, high pre-/low post-, and low pre-/low post-PCI FFR groups, respectively. The risk of TVF was the highest in the low pre-/low post-PCI FFR group among the groups (p values for comparisons <0.05). In addition, the high pre-/low post-PCI FFR group presented a comparable risk of TVF with the high post-PCI FFR groups (p values for comparison >0.05). When the prognostic value of the post-PCI FFR was evaluated according to the pre-PCI FFR, the risk of TVF significantly decreased with an increase in post-PCI FFR in the low pre-PCI FFR group, but not in the high pre-PCI FFR group.

Conclusions

Pre-PCI FFR was associated with clinical outcomes after PCI, and the prognostic value of post-PCI FFR differed according to the pre-PCI FFR.

Trial Registration

ClinicalTrials.gov Identifier: NCT04012281

Clinical and Prognostic Impact From Objective Analysis of Post-Angioplasty Fractional Flow Reserve Pullback

OBJECTIVES

This study sought to evaluate clinical implications of the residual fractional flow reserve (FFR) gradient after angiographically successful percutaneous coronary intervention (PCI).

BACKGROUND

Recent studies have demonstrated FFR measured after PCI is associated with clinical outcome after PCI. Although post-PCI FFR pull back tracings provide clinically relevant information on the residual FFR gradient, there are no objective criteria for assessing post-PCI FFR pull back tracings.

METHODS

A total of 492 patients who underwent angiographically successful PCI and post-PCI FFR measurement with pull back tracings were analyzed. The presence of the major residual FFR gradient after PCI was assessed by both conventional visual interpretation of the pull back tracings and objective analysis using the instantaneous FFR gradient per unit time (dFFR(t)/dt) with a cutoff value of dFFR(t)/dt ≥0.035. Classification agreement between 2 independent operators for the presence of the major residual FFR gradient was compared before and after providing dFFR(t)/dt results. Target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, or clinically driven target vessel revascularization at 2 years, was compared according to the presence of the major residual FFR gradient.

RESULTS

Among the study population, 33.9% had the major residual FFR gradient defined by dFFR(t)/dt. The classification agreement between operators' assessments for the major residual FFR gradient increased with dFFR(t)/dt results compared with conventional visual assessment (Cohen's kappa = 0.633 to 0.819; P < 0.001; intraclass correlation coefficient: 0.776 to 0.901; P < 0.001). Patients with major residual FFR gradient were associated with a higher risk of TVF at 2 years than those without major residual FFR gradient (9.0% vs 2.2%; P < 0.001). Inclusion of the major residual FFR gradient to a clinical prediction model significantly increased discrimination and reclassification ability (C-index = 0.539 vs 0.771; P = 0.006; net reclassification improvement = 0.668; P = 0.007; integrated discrimination improvement = 0.033; P = 0.017) for TVF at 2 years. The presence of the major residual FFR gradient was independently associated with TVF at 2 years, regardless of post-PCI FFR or percent FFR increase (adjusted hazard ratio: 3.930; 95% confidence interval: 1.353-11.420; P = 0.012).

CONCLUSIONS

Objective analysis of post-PCI FFR pull back tracings using dFFR(t)/dt improved classification agreement on the presence of the major residual FFR gradient among operators. Presence of the major residual FFR gradient defined by dFFR(t)/dt after angiographically successful PCI was independently associated with an increased risk of TVF at 2 years. (Automated Algorithm Detecting Physiologic Major Stenosis and Its Relationship with Post-PCI Clinical Outcomes [Algorithm-PCI]; NCT04304677; Influence of FFR on the Clinical Outcome After Percutaneous Coronary Intervention [COE-PERSPECTIVE]; NCT01873560).

Development and Validation of a Risk Nomogram Model for Predicting Revascularization After Percutaneous Coronary Intervention in Patients with Acute Coronary Syndrome

Objective

Percutaneous coronary intervention (PCI) is one of the most effective treatments for acute coronary syndrome (ACS). However, the need for postoperative revascularization remains a major problem in PCI. This study was to develop and validate a nomogram for prediction of revascularization after PCI in patients with ACS.

Methods

A retrospective observational study was conducted using data from 1083 patients who underwent PCI (≥6 months) at a single center from June 2013 to December 2019. They were divided into training (70%; n = 758) and validation (30%; n = 325) sets. Multivariate logistic regression analysis was used to establish a predictive model represented by a nomogram. The nomogram was developed and evaluated based on discrimination, calibration, and clinical efficacy using the concordance statistic (C-statistic), calibration plot and decision curve analysis (DCA), respectively.

Results

The nomogram was comprised of ten variables: follow-up time (odds ratio (OR): 1.01; 95% confidence interval (CI): 1.00-1.03), history of diabetes mellitus (OR: 1.83; 95% CI: 1.25-2.69), serum creatinine level on admission (OR: 0.99; 95% CI: 0.98-1.00), serum uric acid level on admission (OR: 1.005; 95% CI: 1.002-1.007), lipoprotein-a level on admission (OR: 1.0021; 95% CI: 1.0013-1.0029), low density lipoprotein cholesterol level on re-admission (OR: 1.33; 95% CI: 0.10-0.47), the presence of chronic total occlusion (OR: 3.30; 95% CI: 1.93-5.80), the presence of multivessel disease (OR: 4.48; 95% CI: 2.85-7.28), the presence of calcified lesions (OR: 1.63; 95% CI: 1.11-2.39), and the presence of bifurcation lesions (OR: 1.82; 95% CI: 1.20-2.77). The area under the receiver operating characteristic curve values for the training and validation sets were 0.765 (95% CI: 0.732-0.799) and 0.791 (95% CI: 0.742-0.830), respectively. The calibration plots showed good agreement between prediction and observation in both the training and validation sets. DCA also demonstrated that the nomogram was clinically useful.

Conclusion

We developed an easy-to-use nomogram model to predict the risk of revascularization after PCI in patients with ACS. The nomogram may provide useful assessment of risk for subsequent treatment of ACS patients undergoing PCI.

Post-stenting fractional flow reserve vs coronary angiography for optimisation of percutaneous coronary intervention: TARGET-FFR trial

Aims 

A fractional flow reserve (FFR) value ≥0.90 after percutaneous coronary intervention (PCI) is associated with a reduced risk of adverse cardiovascular events. TARGET-FFR is an investigator-initiated, single-centre, randomized controlled trial to determine the feasibility and efficacy of a post-PCI FFR-guided optimization strategy vs. standard coronary angiography in achieving final post-PCI FFR values ≥0.90.

Methods and results 

After angiographically guided PCI, patients were randomized 1:1 to receive a physiology-guided incremental optimization strategy (PIOS) or a blinded coronary physiology assessment (control group). The primary outcome was the proportion of patients with a final post-PCI FFR ≥0.90. Final FFR ≤0.80 was a prioritized secondary outcome. A total of 260 patients were randomized (131 to PIOS, 129 to control) and 68.1% of patients had an initial post-PCI FFR <0.90. In the PIOS group, 30.5% underwent further intervention (stent post-dilation and/or additional stenting). There was no significant difference in the primary endpoint of the proportion of patients with final post-PCI FFR ≥0.90 between groups (PIOS minus control 10%, 95% confidence interval −1.84 to 21.91, P = 0.099). The proportion of patients with a final FFR ≤0.80 was significantly reduced when compared with the angiography-guided control group (−11.2%, 95% confidence interval −21.87 to −0.35], P = 0.045).

Conclusion 

Over two-thirds of patients had a physiologically suboptimal result after angiography-guided PCI. An FFR-guided optimization strategy did not significantly increase the proportion of patients with a final FFR ≥0.90, but did reduce the proportion of patients with a final FFR ≤0.80.

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.

Optimal Prognostication of Patients with Coronary Stenoses in the Pre- and Post-PCI setting: Comments on TARGET FFR and DEFINE-FLOW Trials Presented at TCT Connect 2020

The body of evidence for the use of coronary physiology assessments to guide percutaneous coronary intervention (PCI) has been growing continuously in recent decades. Two studies presented during TCT Connect 2020 added insights into the prognostic value of coronary physiology measurements in pre- and post-PCI settings. The first study, TARGET FFR, assessed whether a post-PCI fractional flow reserve (FFR)-guided incremental optimisation strategy (PIOS) was superior to angiography-guided PCI. The second study, DEFINE-FLOW, assessed the course of stenoses with fractional and coronary flow reserve (FFR+/CFR-) discordance when treated medically. This article summarises the main results from the TARGET FFR and the DEFINE-FLOW trials and puts them into the context of the existing literature.

Role of Post-Stent Physiological Assessment in a Risk Prediction Model After Coronary Stent Implantation

OBJECTIVES

The aim of this study was to develop a risk model incorporating clinical, angiographic, and physiological parameters to predict future clinical events after drug-eluting stent implantation.

BACKGROUND

Prognostic factors after coronary stenting have not been comprehensively investigated.

METHODS

A risk model to predict target vessel failure (TVF) at 2 years was developed from 2,200 patients who underwent second-generation drug-eluting stent implantation and post-stent fractional flow reserve (FFR) measurement. TVF was defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target vessel revascularization. A random survival forest model with automatic feature selection by minimal depth analysis was used for risk model development.

RESULTS

During 2 years of follow-up, the cumulative incidence of TVF was 5.9%. From clinical, angiographic, and physiological parameters, 6 variables were selected for the risk model in order of importance within the model as follows: total stent length, post-stent FFR, age, post-stent percentage diameter stenosis, reference vessel diameter, and diabetes mellitus. Harrell's C index of the random survival forest model was 0.72 (95% confidence interval [CI]: 0.62 to 0.82). This risk model showed better prediction ability than models with clinical risk factors alone (Harrell's C index = 0.55; 95% CI: 0.41 to 0.59; p for comparison = 0.005) and with clinical risk factors and angiographic parameters (Harrell's C index = 0.65; 95% CI: 0.52 to 0.77; p for comparison = 0.045). When the patients were divided into 2 groups according to the median of total stent length (30 mm), post-stent FFR and total stent length showed the highest variable importance in the short- and long-stent groups, respectively.

CONCLUSIONS

A risk model incorporating clinical, angiographic, and physiological predictors can help predict the risk for TVF at 2 years after coronary stenting. Total stent length and post-stent FFR were the most important predictors. (International Post PCI FFR Registry; NCT04012281).

Physiologic Assessment after Coronary Stent Implantation

Post-percutaneous coronary intervention (PCI) physiologic assessment has been featured as an essential tool for evaluation of procedural optimization and prognostication after PCI. The wealth of clinical evidence supports the prognostic role of post-PCI physiologic indices, and interpretation with comprehensive understandings of the complex interaction of post-PCI physiology with atherosclerotic burdens in the stented and non-stented segments provides an insight on the necessity for additional procedure and risk stratification after PCI. With the advancement of technologies in prediction of post-PCI physiologic status in the upfront stage, the clinical utilization of post-PCI physiologic indices will help physicians to attain optimal PCI results.

The presence of myocardial ischemia is a prerequisite for the benefit of coronary revascularization. In the cardiac catheterization laboratory, fractional flow reserve and non-hyperemic pressure ratios are used to define the ischemia-causing coronary stenosis, and several randomized studies showed the benefit of physiology-guided coronary revascularization. However, physiology-guided revascularization does not necessarily guarantee the relief of ischemia. Recent studies reported that residual ischemia might exist in up to 15–20% of cases after angiographically successful percutaneous coronary intervention (PCI). Therefore, post-PCI physiologic assessment is necessary for judging the appropriateness of PCI, detecting the lesions that may benefit from additional PCI, and risk stratification after PCI. This review will focus on the current evidence for post-PCI physiologic assessment, how to interpret these findings, and the future perspectives of physiologic assessment after PCI.

Prognostic Impact of Residual Anatomic Disease Burden After Functionally Complete Revascularization

BACKGROUND

Prognostic impact of residual anatomic disease burden after functionally complete percutaneous coronary intervention (PCI), defined by post-PCI fractional flow reserve (FFR) >0.80 would be a clinically relevant question. The current study evaluated clinical outcomes at 2 years according to residual Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) score (RSS) in patients who underwent functionally complete revascularization.

METHODS

A total of 1910 patients (2095 revascularized vessels) with post-PCI FFR >0.80 were selected from the International Post-PCI FFR Registry. RSS was defined as the SYNTAX score recalculated after PCI, SYNTAX revascularization index was calculated as 100×(1-RSS/pre-PCI SYNTAX score), and post-PCI FFR was measured after completion of PCI. The primary outcome was target vessel failure (TVF; a composite of cardiac death, target vessel-related myocardial infarction, and clinically driven target vessel revascularization) at 2 years, and risk of TVF was compared according to tertile classification of RSS (0, 1-5, and >5) and post-PCI FFR (≥0.94, 0.87-0.93, and ≤0.86).

RESULTS

After PCI, SYNTAX score was changed from 10.0 (Q1-Q3, 7.0-16.0) to 0.0 (Q1-Q3, 0.0-5.0) and FFR changed from 0.70±0.12 to 0.90±0.05. TVF at 2 years occurred in 4.9%, and patients with TVF showed higher pre-PCI SYNTAX score and lower post-PCI FFR than those without. However, there were no significant differences in SYNTAX revascularization index and RSS. The risk of TVF was not different according to tertile of RSS (log-rank P=0.851). Conversely, risk of TVF was different according to tertile of post-PCI FFR (log-rank P=0.009). Multivariable model showed the risk of TVF was significantly associated with post-PCI FFR (hazard ratio, 1.091 [95% CI, 1.032-1.153]; P=0.002) but not with RSS (hazard ratio, 0.969 [95% CI, 0.898-1.045]; P=0.417).

CONCLUSIONS

Among patients who underwent functionally complete revascularization, residual anatomic disease burden assessed by RSS was not related with occurrence of TVF at 2 years. These results support the importance of functionally complete revascularization rather than angiographic complete revascularization. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT04012281.

Prognostic Value of Prerevascularization Fractional Flow Reserve Mediated by the Postrevascularization Level

IMPORTANCE

The prognostic value of pre-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) may be associated with the post-PCI FFR and their interaction. To correctly interpret the prognostic value of pre-PCI FFR, it is essential to understand to what extent the association of pre-PCI FFR with clinical outcomes is explained by post-PCI FFR.

OBJECTIVE

To investigate the extent to which post-PCI FFR mediates the association of pre-PCI FFR with vessel-related outcomes using an international, multicenter collaboration registry.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used pooled patient data from 4 international FFR registries. A total of 1488 patients with pre-PCI FFR of 0.80 or less who underwent elective PCI were included. Data collection was conducted from November 2011 to August 2019, and analysis was conducted from September 2019 to July 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was target vessel failure (TVF) during 2 years of follow-up. The extent to which post-PCI FFR of less than 0.90 mediated the association of pre-PCI FFR less than 0.75 (vs pre-PCI FFR of 0.75 or greater) with TVF was evaluated using a mediation analysis in a counterfactual framework.

RESULTS

Among 1488 patients, the mean (SD) age was 63.5 (9.9) years and 1161 patients (78.0%) were men. The median (interquartile range) pre-PCI and post-PCI FFR were 0.71 (0.62-0.76) and 0.88 (0.83-0.92), respectively. The direct association of low pre-PCI FFR (ie, <0.75) with TVF was significant (odds ratio, 1.81; 95% CI, 1.03-3.17; P = .04), while the mediation by post-PCI FFR level of less than 0.90 was not (indirect association: odds ratio, 1.03; 95% CI, 0.98-1.09; P = .24). In sensitivity analyses using several pre-PCI cutoffs, the mediations by post-PCI FFR were consistently weak.

CONCLUSIONS AND RELEVANCE

In this study, the association of pre-PCI FFR with TVF was not significantly mediated by post-PCI FFR. Poor prognosis due to progressed atherosclerosis, represented as low FFR, may not be reversed by successful PCI that increases FFR. Therefore, the prognostic value of pre-PCI FFR may mainly reflect the global atherosclerotic burden, not the extent of the modifiable epicardial stenosis.

Non-invasive procedural planning using computed tomography-derived fractional flow reserve

Objectives

This study aimed to investigate the performance of computed tomography derived fractional flow reserve based interactive planner (FFR_CT planner) to predict the physiological benefits of percutaneous coronary intervention (PCI) as defined by invasive post‐PCI FFR.

Background

Advances in FFR_CT technology have enabled the simulation of hyperemic pressure changes after virtual removal of stenoses.

Methods

In 56 patients (63 vessels) invasive FFR measurements before and after PCI were obtained and FFR_CT was calculated using pre‐PCI coronary CT angiography. Subsequently, FFR_CT and invasive coronary angiography models were aligned allowing virtual removal of coronary stenoses on pre‐PCI FFR_CT models in the same locations as PCI was performed. Relationships between invasive FFR and FFR_CT, between post‐PCI FFR and FFR_CT planner, and between delta FFR and delta FFR_CT were evaluated.

Results

Pre PCI, invasive FFR was 0.65 ± 0.12 and FFR_CT was 0.64 ± 0.13 (p = .34) with a mean difference of 0.015 (95% CI: −0.23–0.26). Post‐PCI invasive FFR was 0.89 ± 0.07 and FFR_CT planner was 0.85 ± 0.07 (p < .001) with a mean difference of 0.040 (95% CI: −0.10–0.18). Delta invasive FFR and delta FFR_CT were 0.23 ± 0.12 and 0.21 ± 0.12 (p = .09) with a mean difference of 0.025 (95% CI: −0.20–0.25). Significant correlations were found between pre‐PCI FFR and FFR_CT (r = 0.53, p < .001), between post‐PCI FFR and FFR_CT planner (r = 0.41, p = .001), and between delta FFR and delta FFR_CT (r = 0.57, p < .001).

Conclusions

The non‐invasive FFR_CT planner tool demonstrated significant albeit modest agreement with post‐PCI FFR and change in FFR values after PCI. The FFR_CT planner tool may hold promise for PCI procedural planning; however, improvement in technology is warranted before clinical application.

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.].