Physiologic Assessment after Coronary 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.

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.

Physiology- or Imaging-Guided Strategies for Intermediate Coronary Stenosis

Importance

Treatment strategies for intermediate coronary lesions guided by fractional flow reserve (FFR) and intravascular ultrasonography (IVUS) have shown comparable outcomes. Identifying low-risk deferred vessels to ensure the safe deferral of percutaneous coronary intervention (PCI) and high-risk revascularized vessels that necessitate thorough follow-up can help determine optimal treatment strategies.

Objectives

To investigate outcomes according to treatment types and FFR and IVUS parameters after FFR- or IVUS-guided treatment.

Design, Setting, and Participants

This cohort study included patients with intermediate coronary stenosis from the Fractional Flow Reserve and Intravascular Ultrasound-Guided Intervention Strategy for Clinical Outcomes in Patients With Intermediate Stenosis (FLAVOUR) trial, an investigator-initiated, prospective, open-label, multicenter randomized clinical trial that assigned patients into an IVUS-guided strategy (which recommended PCI for minimum lumen area [MLA] ≤3 mm2 or 3 mm2 to 4 mm2 with plaque burden [PB] ≥70%) or an FFR-guided strategy (which recommended PCI for FFR ≤0.80). Data were analyzed from November to December 2022.

Exposures

FFR or IVUS parameters within the deferred and revascularized vessels.

Main Outcomes and Measures

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

Results

A total of 1619 patients (mean [SD] age, 65.1 [9.6] years; 1137 [70.2%] male) with 1753 vessels were included in analysis. In 950 vessels for which revascularization was deferred, incidence of TVF was comparable between IVUS and FFR groups (3.8% vs 4.1%; P = .72). Vessels with FFR greater than 0.92 in the FFR group and MLA greater than 4.5 mm2 or PB of 58% or less in the IVUS group were identified as low-risk deferred vessels, with a decreased risk of TVF (hazard ratio [HR], 0.25 [95% CI, 0.09-0.71]; P = .009). In 803 revascularized vessels, the incidence of TVF was comparable between IVUS and FFR groups (3.6% vs 3.7%; P = .95), which was similar in the revascularized vessels undergoing PCI optimization (4.2% vs 2.5%; P = .31). Vessels with post-PCI FFR of 0.80 or less in the FFR group or minimum stent area of 6.0 mm2 or less or with PB at stent edge greater than 58% in the IVUS group had an increased risk for TVF (HR, 7.20 [95% CI, 3.20-16.21]; P < .001).

Conclusions and Relevance

In this cohort study of patients with intermediate coronary stenosis, FFR- and IVUS-guided strategies showed comparable outcomes in both deferred and revascularized vessels. Binary FFR and IVUS parameters could further define low-risk deferred vessels and high-risk revascularized vessels.

Practical Application of Coronary Physiologic Assessment: Asia-Pacific Expert Consensus Document: Part 1

Coronary physiologic assessment is performed to measure coronary pressure, flow, and resistance or their surrogates to enable the selection of appropriate management strategy and its optimization for patients with coronary artery disease. The value of physiologic assessment is supported by a large body of evidence that has led to major recommendations in clinical practice guidelines. This expert consensus document aims to convey practical and balanced recommendations and future perspectives for coronary physiologic assessment for physicians and patients in the Asia-Pacific region based on updated information in the field that including both wire- and image-based physiologic assessment. This is Part 1 of the whole consensus document, which describes the general concept of coronary physiology, as well as practical information on the clinical application of physiologic indices and novel image-based physiologic assessment.

Clinical and Vessel Characteristics Associated With Hard Outcomes After PCI and Their Combined Prognostic Implications

Background Cardiac death or myocardial infarction still occurs in patients undergoing contemporary percutaneous coronary intervention (PCI). We aimed to identify adverse clinical and vessel characteristics related to hard outcomes after PCI and to investigate their individual and combined prognostic implications. Methods and Results From an individual patient data meta-analysis of 17 cohorts of patients who underwent post-PCI fractional flow reserve measurement after drug-eluting stent implantation, 2081 patients with available clinical and vessel characteristics were analyzed. The primary outcome was cardiac death or target-vessel myocardial infarction at 2 years. The mean age of patients was 64.2±10.2 years, and the mean angiographic percent diameter stenosis was 63.9%±14.3%. Among 11 clinical and 8 vessel features, 4 adverse clinical characteristics (age ≥65 years, diabetes, chronic kidney disease, and left ventricular ejection fraction <50%) and 2 adverse vessel characteristics (post-PCI fractional flow reserve ≤0.80 and total stent length ≥54 mm) were identified to independently predict the primary outcome (all P<0.05). The number of adverse vessel characteristics had additive predictability for the primary end point to that of adverse clinical characteristics (area under the curve 0.72 versus 0.78; P=0.03) and vice versa (area under the curve 0.68 versus 0.78; P=0.03). The cumulative event rate increased in the order of none, either, and both of adverse clinical characteristics ≥2 and adverse vessel characteristics ≥1 (0.3%, 2.4%, and 5.3%; P for trend <0.01). Conclusions In patients undergoing drug-eluting stent implantation, adverse clinical and vessel characteristics were associated with the risk of cardiac death or target-vessel myocardial infarction. Because these characteristics showed independent and additive prognostic value, their integrative assessment can optimize post-PCI risk stratification. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04684043. www.crd.york.ac.uk/prospero/. Unique Identifier: CRD42021234748.

Coronary Physiology-Based Approaches for Plaque Vulnerability: Implications for Risk Prediction and Treatment Strategies

In the catheterization laboratory, the measurement of physiological indexes can help identify functionally significant lesions and has become one of the standard methods to guide treatment decision-making. Plaque vulnerability refers to a coronary plaque susceptible to rupture, enabling risk prediction before coronary events, and it can be detected by defining a certain type of plaque morphology on coronary imaging modalities. Although coronary physiology and plaque vulnerability have been considered different attributes of coronary artery disease, the underlying pathophysiological basis and clinical data indicate a strong correlation between coronary hemodynamic properties and vulnerable plaque. In prediction of coronary events, emerging data have suggested independent and additional implications of a physiology-based approach to a plaque-based approach. This review covers the fundamental interplay between coronary physiology and plaque morphology during disease progression with clinical data supporting this relationship and examines the clinical relevance of physiological indexes in prediction of clinical outcomes and therapeutic decision-making along with plaque vulnerability.

[Modern methods of assessment of physiological significance of coronary lesions: A review]

The article describes the main methods of assessment of physiological significance of coronary artery stenoses, their use in clinical practice and future perspectives. New diagnostic methods that are currently under research are discussed.

Prognostic Value of Measuring Fractional Flow Reserve After Percutaneous Coronary Intervention in Patients With Complex Coronary Artery Disease: Insights From the FAME 3 Trial

BACKGROUND

We evaluate the prognostic value of measuring fractional flow reserve (FFR) after percutaneous coronary intervention (post-PCI FFR) and intravascular imaging in patients undergoing PCI for 3-vessel coronary artery disease in the FAME 3 trial (Fractional Flow Reserve versus Angiography for Multivessel Evaluation).

METHODS

The FAME 3 trial is a multicenter, international, randomized study comparing FFR-guided PCI with coronary artery bypass grafting in patients with multivessel coronary artery disease. PCI was not noninferior with respect to the primary end point of death, myocardial infarction, stroke, or repeat revascularization at 1 year. Post-PCI FFR data were acquired on a patient and vessel-related basis. Intravascular imaging guidance was tracked. The primary end point is a comparison of target vessel failure (TVF) defined as a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization at 1 year based on post-PCI FFR values. Cox regression with robust SEs was used for analysis.

RESULTS

Of the 757 patients randomized to PCI, 461 (61%) had post-PCI FFR measurement and 11.1% had intravascular imaging performed. The median post-PCI FFR was 0.89 [IQR' 0.85-0.94]. On a vessel-level, post-PCI FFR was found to be a significant predictor of TVF univariately (hazard ratio=0.67 [95% CI' 0.48-0.93] for 0.1 unit increase, P=0.0165). On a patient-level, the single lowest post-PCI FFR value was also found to be a significant predictor of TVF univariately (hazard ratio=0.65 [95% CI' 0.48-0.89] for 0.1 unit increase, P=0.0074). Post-PCI FFR was an independent predictor of TVF in multivariable analysis adjusted for key clinical parameters. Outcomes were similar between patients who had intravascular imaging guidance and those who did not.

CONCLUSIONS

Post-PCI FFR measurement was a significant predictor of TVF on a vessel and patient level and an independent predictor of outcomes in a population with complex 3-vessel coronary artery disease eligible for coronary artery bypass grafting. The limited use of intravascular imaging did not affect outcomes.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT02100722.

Prognostic Implications of Fractional Flow Reserve After Coronary Stenting: A Systematic Review and Meta-analysis

IMPORTANCE

Fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) is generally considered to reflect residual disease. Yet the clinical relevance of post-PCI FFR after drug-eluting stent (DES) implantation remains unclear.

OBJECTIVE

To evaluate the clinical relevance of post-PCI FFR measurement after DES implantation.

DATA SOURCES

MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant published articles from inception to June 18, 2022.

STUDY SELECTION

Published articles that reported post-PCI FFR after DES implantation and its association with clinical outcomes were included.

DATA EXTRACTION AND SYNTHESIS

Patient-level data were collected from the corresponding authors of 17 cohorts using a standardized spreadsheet. Meta-estimates for primary and secondary outcomes were analyzed per patient and using mixed-effects Cox proportional hazard regression with registry identifiers included as a random effect. All processes followed the Preferred Reporting Items for Systematic Review and Meta-analysis of Individual Participant Data.

MAIN OUTCOMES AND MEASURES

The primary outcome was target vessel failure (TVF) at 2 years, a composite of cardiac death, target vessel myocardial infarction (TVMI), and target vessel revascularization (TVR). The secondary outcome was a composite of cardiac death or TVMI at 2 years.

RESULTS

Of 2268 articles identified, 29 studies met selection criteria. Of these, 28 articles from 17 cohorts provided data, including a total of 5277 patients with 5869 vessels who underwent FFR measurement after DES implantation. Mean (SD) age was 64.4 (10.1) years and 4141 patients (78.5%) were men. Median (IQR) post-PCI FFR was 0.89 (0.84-0.94) and 690 vessels (11.8%) had a post-PCI FFR of 0.80 or below. The cumulative incidence of TVF was 340 patients (7.2%), with cardiac death or TVMI occurring in 111 patients (2.4%) at 2 years. Lower post-PCI FFR significantly increased the risk of TVF (adjusted hazard ratio [HR] per 0.01 FFR decrease, 1.04; 95% CI, 1.02-1.05; P < .001). The risk of cardiac death or MI also increased inversely with post-PCI FFR (adjusted HR, 1.03; 95% CI, 1.00-1.07, P = .049). These associations were consistent regardless of age, sex, the presence of hypertension or diabetes, and clinical diagnosis.

CONCLUSIONS AND RELEVANCE

Reduced FFR after DES implantation was common and associated with the risks of TVF and of cardiac death or TVMI. These results indicate the prognostic value of post-PCI physiologic assessment after DES implantation.

Finite Element Analysis of Fluid–Structure Interaction in a Model of an L-Type Mg Alloy Stent-Stenosed Coronary Artery System

The coronary stent deployment and subsequent service process is a complex geometric/physical nonlinear and fluid–structure coupling system. Analyzing the distribution of stress–strain on the stent is of great significance in studying the deformation and failure behavior. A coupled system dynamics model comprising stenotic coronary artery vessels and L-type Mg alloy stents was established by applying the polynomial hyperelastic constitutive theory. The nonlinear, significant deformation behavior of the stent was systematically studied. The stress–strain distribution of the coupling system during stent deployment was analyzed. The simulation results show that the edges of the supporting body fixed without a bridge are the weakest zone. The stress changes on the inside of the wave of the supporting body are very large, and the residual stress accumulated in this area is the highest. The peak stress of the plaque and the arterial wall was lower than the damage threshold. The velocity of the blood between the wave crest of the supporting body is large and the streamline distribution is concentrated. In addition, the inner surface pressure on the stent is evenly distributed along its axial dimension. The maximum arterial wall shear stress always appears on the inside of the wave crest of the supporting body fixed with a bridge, and, as such, the largest obstacle to the blood flow is in this zone.

Physiological Approach for Coronary Artery Bifurcation Disease: Position Statement by Korean, Japanese, and European Bifurcation Clubs

Coronary artery bifurcation lesions are frequently encountered in cardiac catheterization laboratories and are associated with more complex procedures and worse clinical outcomes than nonbifurcation lesions. Therefore, anatomical and physiological assessment of bifurcation lesions before, during, and after percutaneous coronary intervention is of paramount clinical importance. Physiological assessment can help interventionalists appreciate the hemodynamic significance of coronary artery disease and guide ischemia-directed revascularization. However, it is important to understand that the physiological approach for bifurcation disease is more important than simply using physiological indexes for its assessment. This joint consensus document by the Korean, Japanese, and European bifurcation clubs presents the concept of a physiological approach for coronary bifurcation lesions, as well as current knowledge, practical tips, pitfalls, and future directions of applying physiological indexes in bifurcation percutaneous coronary intervention. This document aims to guide interventionalists in performing appropriate physiology-based assessments and treatment decisions for coronary bifurcation lesions.

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

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.

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.

High-Risk Morphological and Physiological Coronary Disease Attributes as Outcome Markers After Medical Treatment and Revascularization

OBJECTIVES

This study sought to evaluate the prognostic impact of plaque morphology and coronary physiology on outcomes after medical treatment or percutaneous coronary intervention (PCI).

BACKGROUND

Although fractional flow reserve (FFR) is currently best practice, morphological characteristics of coronary artery disease also contribute to outcomes.

METHODS

A total of 872 vessels in 538 patients were evaluated by invasive FFR and coronary computed tomography angiography. High-risk attributes (HRA) were defined as high-risk physiological attribute (invasive FFR ≤0.8) and high-risk morphological attributes including: 1) local plaque burden (minimum lumen area <4 mm² and plaque burden ≥70%); 2) adverse plaque characteristics ≥2; and 3) global plaque burden (total plaque volume ≥306.5 mm³ and percent atheroma volume ≥32.2%). The primary outcome was the composite of revascularization, myocardial infarction, or cardiac death at 5 years.

RESULTS

The mean FFR was 0.88 ± 0.08, and PCI was performed in 239 vessels. The primary outcome occurred in 54 vessels (6.2%). All high-risk morphological attributes were associated with the increased risk of adverse outcomes after adjustment for FFR ≤0.8 and demonstrated direct prognostic effect not mediated by FFR ≤0.8. The 5-year event risk proportionally increased as the number of HRA increased (p for trend <0.001) with lower risk in the PCI group than the medical treatment group in vessels with 1 or 2 HRA (9.7% vs. 14.7%), but not in vessels with either 0 or ≥3 HRA. Of the vessels with pre-procedural FFR ≤0.8, ischemia relief by PCI (pre-PCI FFR ≤0.8 and post-PCI FFR >0.8) significantly reduced vessel-oriented composite outcome risk compared with medical treatment alone in vessels with 0 or 1 high-risk morphological attributes (hazard ratio: 0.33; 95% confidence interval: 0.12 to 0.93; p = 0.035), but the risk reduction was attenuated in vessels with ≥2 high-risk morphological attributes.

CONCLUSIONS

High-risk morphological attributes offered additive prognostic value to coronary physiology and may optimize selection of treatment strategies by adding to FFR-based risk predictions (CCTA-FFR Registry for Development of Comprehensive Risk Prediction Model; NCT04037163).