Association of Lower Fractional Flow Reserve Values With Higher Risk of Adverse Cardiac Events for Lesions Deferred Revascularization Among Patients With Acute Coronary Syndrome

Patient-Specific Numerical Simulations of Coronary Artery Hemodynamics and Biomechanics: A Pathway to Clinical Use

PURPOSE

Numerical models that simulate the behaviors of the coronary arteries have been greatly improved by the addition of fluid-structure interaction (FSI) methods. Although computationally demanding, FSI models account for the movement of the arterial wall and more adequately describe the biomechanical conditions at and within the arterial wall. This offers greater physiological relevance over Computational Fluid Dynamics (CFD) models, which assume the walls do not move or deform. Numerical simulations of patient-specific cases have been greatly bolstered by the use of imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Imaging (MRI), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS) to reconstruct accurate 2D and 3D representations of artery geometries. The goal of this study was to conduct a comprehensive review on CFD and FSI models on coronary arteries, and evaluate their translational potential.

METHODS

This paper reviewed recent work on patient-specific numerical simulations of coronary arteries that describe the biomechanical conditions associated with atherosclerosis using CFD and FSI models. Imaging modality for geometry collection and clinical applications were also discussed.

RESULTS

Numerical models using CFD and FSI approaches are commonly used to study biomechanics within the vasculature. At high temporal and spatial resolution (compared to most cardiac imaging modalities), these numerical models can generate large amount of biomechanics data.

CONCLUSIONS

Physiologically relevant FSI models can more accurately describe atherosclerosis pathogenesis, and help to translate biomechanical assessment to clinical evaluation.

Contemporary Use of Coronary Physiology in Cardiology

Coronary angiography has a limited ability to predict the functional significance of intermediate coronary lesions. Hence, physiological assessment of coronary lesions, via fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), has been introduced to determine their functional significance. An accumulating body of evidence has consolidated the role of physiology-guided revascularization, particularly among patients with stable ischemic heart disease. The use of FFR or iFR to guide decision-making in patients with stable ischemic heart disease and intermediate coronary lesions received a class I recommendation from major societal guidelines. Nevertheless, the role of coronary physiology testing is less clear among certain patients' groups, including patients with serial coronary lesions, acute coronary syndromes, aortic stenosis, heart failure, as well as post-percutaneous coronary interventions. In this review, we aimed to discuss the utility and clinical evidence of coronary physiology (mainly FFR and iFR), with emphasis on those specific patient groups.

Acute Coronary Syndrome with Non-Obstructive Plaque on Angiography and Features of Vulnerable Plaque on Intracoronary Optical Coherence Tomography

Optical coherence tomography (OCT) has a high spatial resolution and is useful in identifying coronary lesions with high-risk features (vulnerable plaques). These plaques are strongly associated with acute coronary syndrome (ACS). In this report, we present the case of a 43-year-old male patient presenting with typical chest pain that began three hours prior to admission. The patient exhibited an elevation of the ST segments of the anterior and lateral walls. Invasive stratification revealed a 40% lesion in the middle segment of the left anterior descending (LAD) artery. The patient was given optimized clinical treatment as he had a nonobstructive lesion in the LAD at the time of angiography. During the treatment, the patient continued to complain of angina on exertion. A follow-up coronary angiography, along with OCT analysis of the middle-to-moderate lesion in the LAD, revealed a plaque predominantly rich in lipids with signs of vulnerability. A percutaneous coronary intervention was performed. The patient's recovery was uneventful, and he was discharged the day after the procedure. This case illustrates the evolution of intravascular imaging, particularly OCT, in the detection of vulnerable plaques.

Clinical Outcome of Revascularization Deferral With Instantaneous Wave-Free Ratio and Fractional Flow Reserve: A 5-Year Follow-Up Substudy From the iFR-SWEDEHEART Trial

Background Although physiology-based assessment of coronary artery stenosis using instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) are established methods of guiding coronary revascularization, its clinical outcome in long-term deferral needs further evaluation, especially with acute coronary syndrome as a clinical presentation. The aim was to evaluate the long-term clinical outcome of deferral of revascularization based on iFR or FFR. Methods and Results This is a substudy of the iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trial, where patients deferred from revascularization from each study arm were selected. Nine hundred eight patients deferred from coronary revascularization with iFR (n=473) and FFR (n=435) were followed for 5 years. The national quality registry, SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies), was used for patient data collection and clinical follow-up. The end point was major adverse cardiac events and their individual components all-cause death, cardiovascular death, noncardiovascular death, nonfatal myocardial infarction, and unplanned revascularization. No significant difference was found in major adverse cardiac events (iFR 18.6% versus FFR 16.8%; adjusted hazard ratio, 1.08 [95% CI, 0.79-1.48]; P=0.63) or their individual components. Conclusions No differences in clinical outcomes after 5-year follow-up were noted when comparing iFR versus FFR as methods for deferral of coronary revascularization in patients presenting with stable angina pectoris and acute coronary syndrome. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02166736.

Compared Outcomes of ST-Elevation Myocardial Infarction Patients with Multivessel Disease Treated with Primary Percutaneous Coronary Intervention and Preserved Fractional Flow Reserve of Non-Culprit Lesions Treated Conservatively and of Those with Low Fractional Flow Reserve Managed Invasively: Insights from the FLOWER MI trial

Background: In patients with ST-elevation myocardial infarction (STEMI) and multivessel disease, percutaneous coronary intervention (PCI) for non-culprit lesions guided by FFR is superior to treatment of the culprit lesion alone. Whether deferring non-culprit PCI is safe in this specific context is questionable. We aimed to assess clinical outcomes at one-year in STEMI patients with multivessel coronary artery disease and an FFR-guided strategy for non-culprit lesions, according to whether or not ≥1 PCI was performed. Methods: Outcomes were analyzed in patients of the randomized FLOWER MI (Flow Evaluation to Guide Revascularization in Multivessel ST-Elevation Myocardial Infarction) trial in whom, after successful primary PCI, non-culprit lesions were assessed using FFR. The primary outcome was a composite of all-cause death, non-fatal MI, and unplanned hospitalization with urgent revascularization at one year. Results: Among 1,171 patients enrolled in this study, 586 were assigned to the FFR-guided group: 388 (66%) of them had ≥1 PCI and 198 (34%) had no PCI. Mean FFR before decision (i.e., PCI or not) of non-culprit lesions were 0.75±0.10 and 0.88±0.06, respectively. During follow-up, a primary outcome event occurred in 16 of 388 patients (4.1%) in patients with PCI and in 16 of 198 patients (8.1%) in patients without PCI (adjusted hazard ratio, 0.42; 95% confidence interval, 0.20 to 0.88; P = 0.02). Conclusions: In patients with STEMI undergoing complete revascularization guided by FFR measurement, those with ≥1 PCI had lower event rates at 1 year, compared with patients with deferred PCI, suggesting that deferring lesions judged relevant by visual estimation but with FFR >0.80 may not be optimal in this context. Future randomized studies are needed to confirm this data.

Identification of anatomic risk factors for acute coronary events by optical coherence tomography in patients with myocardial infarction and residual nonflow limiting lesions: rationale and design of the PECTUS-obs study

INTRODUCTION

In patients with myocardial infarction, the decision to treat a nonculprit lesion is generally based on its physiological significance. However, deferral of revascularisation based on nonischaemic fractional flow reserve (FFR) values in these patients results in less favourable outcomes compared with patients with stable coronary artery disease, potentially caused by vulnerable nonculprit lesions. Intravascular optical coherence tomography (OCT) imaging allows for in vivo morphological assessment of plaque 'vulnerability' and might aid in the detection of FFR-negative lesions at high risk for recurrent events.

METHODS AND ANALYSIS

The PECTUS-obs study is an international multicentre prospective observational study that aims to relate OCT-derived vulnerable plaque characteristics of nonflow limiting, nonculprit lesions to clinical outcome in patients with myocardial infarction. A total of 438 patients presenting with myocardial infarction (ST-elevation myocardial infarction and non-ST-elevation myocardial infarction) will undergo OCT-imaging of any FFR-negative nonculprit lesion for detection of plaque vulnerability. The primary study endpoint is a composite of major adverse cardiovascular events (all-cause mortality, nonfatal myocardial infarction or unplanned revascularisation) at 2-year follow-up. Secondary endpoints will be the same composite at 1-year and 5-year follow-up, target vessel failure, target vessel revascularisation, target lesion failure and target lesion revascularisation.

ETHICS AND DISSEMINATION

This study has been approved by the Medical Ethics Committee of the region Arnhem-Nijmegen. The results of this study will be disseminated in a main paper and additional papers with subgroup analyses.

TRIAL REGISTRATION NUMBER

NCT03857971.

Completeness of revascularisation in acute coronary syndrome patients with multivessel disease

A significant proportion of patients presenting with acute coronary syndromes (ACS) have multivessel disease (MVD). Despite the abundance of clinical trials in this area, several questions regarding the procedure of complete coronary revascularisation remain unanswered. This state-of-the-art review summarises the latest evidence on complete revascularisation (CR) in this subset of patients and critically appraises clinical decision making based on non-culprit lesion (NCL) assessment. Future areas of research are put into perspective.

Wall shear stress estimated by 3D-QCA can predict cardiovascular events in lesions with borderline negative fractional flow reserve

BACKGROUND AND AIMS

There is some evidence of the implications of wall shear stress (WSS) derived from three-dimensional quantitative coronary angiography (3D-QCA) models in predicting adverse cardiovascular events. This study investigates the efficacy of 3D-QCA-derived WSS in detecting lesions with a borderline negative fractional flow reserve (FFR: 0.81-0.85) that progressed and caused events.

METHODS

In this retrospective cohort study, we identified 548 patients who had at least one lesion with an FFR 0.81-0.85 and complete follow-up data; 293 lesions (286 patients) with suitable angiographic characteristics were reconstructed using a dedicated 3D-QCA software and included in the analysis. In the reconstructed models blood flow simulation was performed and the value of 3D-QCA variables and WSS distribution in predicting events was examined. The primary endpoint of the study was the composite of cardiac death, target lesion related myocardial infarction or clinically indicated target lesion revascularization.

RESULTS

During a median follow-up of 49.4 months, 37 events were reported. Culprit lesions had a greater area stenosis [(AS), 66.1% (59.5-72.3) vs 54.8% (46.5-63.2), p<0.001], smaller minimum lumen area [(MLA), 1.66 mm² (1.45-2.30) vs 2.10 mm² (1.69-2.70), p=0.011] and higher maximum WSS [9.0 Pa (5.10-12.46) vs 5.0 Pa (3.37-7.54), p < 0.001] than those that remained quiescent. In multivariable analysis, AS [hazard ratio (HR): 1.06, 95% confidence interval (CI): 1.03-1.10, p=0.001] and maximum WSS (HR: 1.08, 95% CI: 1.02-1.14, p=0.012) were the only independent predictors of the primary endpoint. Lesions with an increased AS (≥58.6%) that were exposed to high WSS (≥7.69Pa) were more likely to progress and cause events (27.8%) than those with a low AS exposed to high WSS (7.4%) or those exposed to low WSS that had increased (12.8%) or low AS (2.7%, p<0.001).

CONCLUSIONS

This study for the first time highlights the potential value of 3D-QCA-derived WSS in detecting, among lesions with a borderline negative FFR, those that cause cardiovascular events.

Pre-Emptive OCT-Guided Angioplasty of Vulnerable Intermediate Coronary Lesions: Results from the Prematurely Halted PECTUS-Trial

Objectives

To assess the safety and efficacy of pre-emptive treatment of optical coherence tomography- (OCT-) derived vulnerable, non-flow-limiting, non-culprit lesions in patients with myocardial infarction (MI).

Background

Intracoronary imaging with OCT can aid in the decision to treat non-flow-limiting lesions by identifying vulnerable plaques. Pre-emptive treatment of these lesions might improve patient outcome by “sealing” these plaques. Bioresorbable vascular scaffolds (BVS) have theoretical benefit for this treatment because they dissolve completely over time.

Methods

In patients presenting with MI, non-culprit lesions with a fractional flow reserve ≥0.8 were imaged with OCT. Vulnerable plaques were randomised to either percutaneous coronary intervention (PCI) with bioresorbable vascular scaffold (BVS) placement or optimal medicinal therapy (OMT). The primary outcome was a composite of all-cause mortality, non-fatal MI, and unplanned revascularisation at 1-year follow-up.

Results

The trial was stopped prematurely after retraction from the market of the Absorb BVS. At that time, a total of 34 patients were randomised. At two years, the composite endpoint occurred 3 times (18.8%) in the BVS group and 1 time (6.3%) in the OMT group. Apart from one elective PCI for stable angina in the OMT group, no target lesions in any group were revascularised.

Conclusions

Pre-emptive stenting of vulnerable plaques had no evident benefit compared to conservative treatment. However, due to the low number of included patients, no definite conclusions could be drawn. Identifying and potentially treating vulnerable plaques remains an important target for future research. This trial is registered under https://www.trialregister.nl/trial/NL4177 on 08-12-2015.

Impact of malondialdehyde-modified low-density lipoprotein on clinical outcomes after fractional flow reserve-guided deferral of revascularization

Cardiovascular events can occur after deferred revascularization, and malondialdehyde-modified low-density lipoprotein (MDA-LDL) has been suggested to be an atherogenic marker. We investigated the relationship between serum MDA-LDL levels and clinical outcomes in patients with fractional flow reserve (FFR)-guided deferral of revascularization. Among 3084 patients undergoing coronary angiography, we retrospectively analyzed 127 patients with intermediate stenosis and deferred revascularization based on FFR > 0.80. Median follow-up interval was 30.4 months, and serum MDA-LDL was measured prior to the measurement of FFR. We evaluated the composite of major adverse cardiac events (MACEs), including cardiac death, myocardial infarction, ischemia-driven deferred lesion revascularization, and any revascularization. MACEs occurred in 18 (14.2%) patients. The MACE group presented with significantly higher MDA-LDL levels than the non-MACE group (134.9 ± 33.3 U/L vs. 95.6 ± 32.2 U/L, P < 0.001). In analysis of the receiver operating characteristics curve for the prediction of MACEs, MDA-LDL presented a significantly larger area under the curve than low-density lipoprotein-cholesterol (LDL-C; 0.810 vs. 0.687, P = 0.042). Univariate Cox regression analysis indicated a significant relationship between MACEs and MDA-LDL (per 10 U/L, HR 1.20; P = 0.004), as did the multivariate model (per 10 U/L, HR 1.17; P = 0.019). When compared according to the median LDL-C (98 mg/dL), the MACE group had significantly higher MDA-LDL in both the high (147.2 ± 27.3 U/L vs. 113.9 ± 31.2 U/L, P = 0.001) and low (103.2 ± 27.3 U/L vs. 80.2 ± 24.0 U/L, P = 0.045) LDL-C groups. Serum MDA-LDL levels were associated with cardiac events in patients with deferral of revascularization based on FFR.

Long-term outcome after deferred revascularization due to negative fractional flow reserve in intermediate coronary lesions

Objectives

The aim was to assess long‐term outcome after deferring intervention of coronary lesions with a fractional flow reserve (FFR) value of >0.80 in a real‐world patient population and then to identify factors associated with deferred target lesion failure (DTLF).

Background

Deferring coronary interventions of intermediate lesions based on FFR measurement is safe, irrespective of the extent of coronary artery disease. However, FFR values near the cut‐off of >0.80 may have less favorable outcome.

Methods

A retrospective analysis was performed in patients with deferred coronary intervention based on FFR value >0.80. The primary endpoint was DTLF, a composite of acute coronary syndrome (ACS) and any coronary revascularization, related to the initially deferred stenosis.

Results

A total of 600 patients, mean age of 66 ± 10 years, and 751 coronary lesions with negative FFR values (mean 0.88 ± 0.04) were included. The mean follow‐up was 27 ± 15 months. DTLF occurred in 44 patients (7.3%), revascularization in 42 (7%), and ACS without revascularization in 2 patients (0.3%). Patients with DTLF more often had diabetes mellitus, previous coronary artery bypass grafting, multivessel disease (MVD), and lower FFR at inclusion. Multivariable regression analysis showed that lower deferred FFR values [FFR 0.81–0.85: hazard ratio (HR) 2.79 (95% CI [confidence interval]; 1.46–5.32), p .002], MVD [HR 1.98 (95% CI; 1.05–3.75), p .036], distal lesions [HR 2.43 (95% CI; 1.29–4.57), p .006], and lesions located in a saphenous vein graft (SVG) [HR 6.35 (95% CI; 1.81–22.28), p .004] were independent predictors for DTLF.

Conclusions

The long‐term rate of DTLF of initially deferred coronary lesions was 7.3%. Independent predictors for DTLF are lower deferred FFR value, the presence of MVD, distal lesions, and lesions in SVG.

Safety of the Deferral of Coronary Revascularization on the Basis of Instantaneous Wave-Free Ratio and Fractional Flow Reserve Measurements in Stable Coronary Artery Disease and Acute Coronary Syndromes

OBJECTIVES

The aim of this study was to investigate the clinical outcomes of patients deferred from coronary revascularization on the basis of instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements in stable angina pectoris (SAP) and acute coronary syndromes (ACS).

BACKGROUND

Assessment of coronary stenosis severity with pressure guidewires is recommended to determine the need for myocardial revascularization.

METHODS

The safety of deferral of coronary revascularization in the pooled per-protocol population (n = 4,486) of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) and iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trials was investigated. Patients were stratified according to revascularization decision making on the basis of iFR or FFR and to clinical presentation (SAP or ACS). The primary endpoint was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year.

RESULTS

Coronary revascularization was deferred in 2,130 patients. Deferral was performed in 1,117 patients (50%) in the iFR group and 1,013 patients (45%) in the FFR group (p < 0.01). At 1 year, the MACE rate in the deferred population was similar between the iFR and FFR groups (4.12% vs. 4.05%; fully adjusted hazard ratio: 1.13; 95% confidence interval: 0.72 to 1.79; p = 0.60). A clinical presentation with ACS was associated with a higher MACE rate compared with SAP in deferred patients (5.91% vs. 3.64% in ACS and SAP, respectively; fully adjusted hazard ratio: 0.61 in favor of SAP; 95% confidence interval: 0.38 to 0.99; p = 0.04).

CONCLUSIONS

Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year.

Functional disorders in non-culprit coronary arteries and their implications in patients with acute myocardial infarction

Approximately 30-50% of patients with ST-segment elevation acute myocardial infarction have multivessel disease. The physiology of the non-culprit artery (NCA) is complex and represents a challenge to physicians as, while these plaques are presumably stable, clinical data show that they frequently lead to major adverse cardiovascular events. In addition the presence of microvascular and endothelial dysfunction may have prognostic implications and interfere with current physiological indices for stenosis severity assessment. In this review we aim to summarize current methods to study the microcirculation, discuss the evidence available regarding the endothelium and the microvascular compartment of the NCA; the best strategies to perform a complete revascularization based on proven ischemia; real limitations associated to hyperemic stenosis indices; and the potential role of novel resting-indices in this specific acute context.

Fractional flow reserve in acute coronary syndrome: a meta-analysis and systematic review

Background

The utility of fractional flow reserve (FFR) to guide revascularisation in the management of acute coronary syndrome (ACS) remains unclear.

Objective

This study aims to compare the clinical outcomes of patients following FFR-guided revascularisation for either ACS or stable angina (SA) and in particular focuses on the outcome of those with deferred revascularisation after FFR.

Methods

A meta-analysis of existing literature was performed. Outcomes including the rate of major adverse cardiovascular events (MACE), recurrent myocardial infarction (MI), mortality and unplanned revascularisation were analysed.

Results

A review of 937 records yielded 9 studies comparing 5457 patients, which were included in the analyses. Patients with ACS had a higher rate of recurrent MI (OR 1.81, p=0.02) and a strong trend towards more MACE and all-cause mortality compared with patients with SA when treated by an FFR-guided revascularisation strategy. Deferral of invasive therapy on the basis of FFR led to a higher rate of MACE (17.6% vs 7.3 %; p=0.004), recurrent MI (5.3% vs 1.5%, p=0.001) and target vessel revascularisation (16.4% vs 5.6 %; p=0.02) in patients with ACS, and a strong trend towards a higher cardiovascular mortality at follow-up when compared with patients with SA.

Conclusion

The event rate in patients with ACS is much higher than SA despite following an FFR-guided revascularisation strategy. Deferring revascularisation does not appear to be as safe for ACS as it is for SA using contemporary FFR cut-offs validated in SA. Refinement of the therapeutic strategy for patients with ACS with multivessel disease is needed to redress the balance.

Fractional Flow Reserve-Guided Strategy in Acute Coronary Syndrome. A Systematic Review and Meta-Analysis

Background

There are limited data on the prognosis of deferral of lesion treatment in patients with acute coronary syndrome (ACS) based on fractional flow reserve (FFR).

Objectives

To provide a systematic review of the current evidence on the prognosis of deferred lesions in ACS patients compared with deferred lesions in non-ACS patients, on the basis of FFR.

Methods

We searched Medline, EMBASE, and the Cochrane Library for studies published between January 2000 and September 2017 that compared prognosis of deferred revascularization of lesions on the basis of FFR in ACS patients compared with non-ACS patients. We conducted a pooled relative risk meta-analysis of four primary outcomes: mortality, cardiovascular (CV) mortality, myocardial infarction (MI) and target-vessel revascularization (TVR).

Results

We identified 7 studies that included a total of 5,107 patients. A pooled meta-analysis showed no significant difference in mortality (relative risk [RR] = 1.44; 95% CI, 0.9-2.4), CV mortality (RR = 1.29; 95% CI = 0.4-4.3) and TVR (RR = 1.46; 95% CI = 0.9-2.3) after deferral of revascularization based on FFR between ACS and non-ACS patients. Such deferral was associated with significant additional risk of MI (RR = 1.83; 95% CI = 1.4-2.4) in ACS patients.

Conclusion

The prognostic value of FFR in ACS setting is not as good as in stable patients. The results demonstrate an increased risk of MI but not of mortality, CV mortality, and TVR in ACS patients.

Role of fractional flow reserve in the evaluation and management of patients with acute coronary syndrome

PURPOSE OF REVIEW

The aim of this review is to appraise the clinical and prognostic value and pitfalls of FFR across different spectra of ACS presentations and lesion subsets.

RECENT FINDINGS

Preponderance of evidence on this subject is from observational nonrandomized studies with conflicting results and short-term outcomes. Multiple recent studies evaluating the role of FFR-based deferral in non-STE ACS from a potentially culprit lesion have demonstrated poor long-term prognosis as related to future risk of target vessel failure (myocardial infarction/revascularization). The prognostic power of nonischemic FFR seems favorable in clear nonculprit ACS lesions.

SUMMARY

Fractional flow reserve evaluation can be helpful in clinical decision-making for certain subsets of ACS patients and lesions. Definite ACS-producing lesions should not be evaluated using FFR due to altered pathophysiology and distinct mechanisms underlying the disease process. In uncertain culprit lesions, FFR may be useful with complementary intracoronary imaging.

Impact of Routine Fractional Flow Reserve on Management Decision and 1-Year Clinical Outcome of Patients With Acute Coronary Syndromes: PRIME-FFR (Insights From the POST-IT [Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease] and R3F [French FFR Registry] Integrated Multicenter Registries - Implementation of FFR [Fractional Flow Reserve] in Routine Practice)

BACKGROUND

Fractional flow reserve (FFR) is not firmly established as a guide to treatment in patients with acute coronary syndromes (ACS). Primary goals were to evaluate the impact of integrating FFR on management decisions and on clinical outcome of patients with ACS undergoing coronary angiography, as compared with patients with stable coronary artery disease.

METHODS AND RESULTS

R3F (French FFR Registry) and POST-IT (Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease), sharing a common design, were pooled as PRIME-FFR (Insights From the POST-IT and R3F Integrated Multicenter Registries - Implementation of FFR in Routine Practice). Investigators prospectively defined management strategy based on angiography before performing FFR. Final decision after FFR and 1-year clinical outcome were recorded. From 1983 patients, in whom FFR was prospectively used to guide treatment, 533 sustained ACS (excluding acute ST-segment-elevation myocardial infarction). In ACS, FFR was performed in 1.4 lesions per patient, mostly in left anterior descending (58%), with a mean percent stenosis of 58±12% and a mean FFR of 0.82±0.09. In patients with ACS, reclassification by FFR was high and similar to those with non-ACS (38% versus 39%; P=NS). The pattern of reclassification was different, however, with less patients with ACS reclassified from revascularization to medical treatment compared with those with non-ACS (P=0.01). In ACS, 1-year outcome of patients reclassified based on FFR (FFR against angiography) was as good as that of nonreclassified patients (FFR concordant with angiography), with no difference in major cardiovascular event (8.0% versus 11.6%; P=0.20) or symptoms (92.3% versus 94.8% angina free; P=0.25). Moreover, FFR-based deferral to medical treatment was as safe in patients with ACS as in patients with non-ACS (major cardiovascular event, 8.0% versus 8.5%; P=0.83; revascularization, 3.8% versus 5.9%; P=0.24; and freedom from angina, 93.6% versus 90.2%; P=0.35). These findings were confirmed in ACS explored at the culprit lesion. In patients (6%) in whom the information derived from FFR was disregarded, a dire outcome was observed.

CONCLUSIONS

Routine integration of FFR into the decision-making process of ACS patients with obstructive coronary artery disease is associated with a high reclassification rate of treatment (38%). A management strategy guided by FFR, divergent from that suggested by angiography, including revascularization deferral, is safe in ACS.

Improving myocardial fractional flow reserve in coronary atherosclerosis via CX37 gene silence: a preclinical validation study in pigs

OBJECTIVES

The purpose of this study was to evaluate the effect of CX37 gene silence on myocardial fractional flow reserve (FFR).

METHODS

A total of 90 male pigs were randomly divided into saline, mock and 3 different doses (5, 10 and 20 µl) of CX37 viral suspension groups that could induce coronary plaque formation with high-fat diet. After performing myocardial FFR by intravascular ultrasound, different doses of CX37 viral suspension, saline and mock small interfering RNA (siRNA) were transfected into the related coronary. The FFR, the myocardial enzymes and the cardiac structures and functions of the pigs were detected at baseline, 4th, 8th and 12th week after transfection, respectively.

RESULTS

Repeated measures analysis of variance comparison showed that the difference in the FFR among the 5 groups was statistically significant (F = 27.0, P < 0.01). Post hoc analysis showed that FFR were highest in the siRNA CX37 group (20 µl), followed by the siRNA CX37 group (10 µl) and the siRNA CX37 group (5 µl), and lowest in the mock and saline groups. Left ventricular end-diastolic diameter was significantly smaller and ejection fraction was obviously higher in the 3 siRNA CX37 groups compared with the untreated groups.

CONCLUSIONS

Our study showed that FFR levels increased along with decreased doses of siRNA CX37 lentivirus, indicating that siRNA CX37 lentivirus may reduce the risk of coronary atherosclerosis and provide a potential approach to treat coronary heart disease.

Should fraction flow reserve be considered an important decision-making tool to stratify patients with stable coronary artery disease for percutaneous coronary intervention?: A meta-analysis

BACKGROUND

Nowadays, fraction flow reserve (FFR) is being discussed in every percutaneous coronary intervention (PCI) capable hospitals. Owing to recent development in the medical field, FFR-guided PCI should be able to find a place in Interventional Cardiology. At present, the importance of FFR to stratify patients who require PCI has seldom systematically been investigated. In this analysis, we aimed to compare the major adverse cardiac events (MACEs) mainly in patients with stable coronary artery disease (CAD) to whom PCI was recommended and deferred respectively based on the FFR value.

METHODS

Electronic databases were searched for studies comparing FFR-recommended versus FFR-deferred coronary stenting. Long-term MACEs, mortality, and myocardial infarction (MI) were considered as the clinical endpoints in this analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated and the analyses were carried out by the latest version of the RevMan software.

RESULTS

A total number of 1753 patients (670 patients were revascularized, whereas 1083 patients were deferred from revascularization based on the FFR value) were analyzed. Current results showed MACEs and MI were significantly higher in the FFR-recommended PCI group with OR 1.34 (95% CI: 1.05-1.72; P = .02) and OR 1.73 (95% CI: 1.19-2.51; P = .004, I = 0%), respectively. However, mortality was similarly manifested with OR 1.23 (95% CI: 0.92-1.63; P = .16, I = 0%).

CONCLUSION

Significantly higher MACEs were observed in patients to whom PCI was recommended compared to those patients who were deferred from undergoing PCI based on the FFR values. Therefore, FFR might indeed be an important decision-making procedural tool, which should be used to stratify stable CAD patients with an advanced disease and who are qualified candidates for PCI. Further research should confirm this hypothesis.

Fractional Flow Reserve and Cardiac Events in Coronary Artery Disease: Data From a Prospective IRIS-FFR Registry (Interventional Cardiology Research Incooperation Society Fractional Flow Reserve)

BACKGROUND

We evaluated the prognosis of deferred and revascularized coronary stenoses after fractional flow reserve (FFR) measurement to assess its revascularization threshold in clinical practice.

METHODS

The IRIS-FFR registry (Interventional Cardiology Research In-cooperation Society Fractional Flow Reserve) prospectively enrolled 5846 patients with ≥1coronary lesion with FFR measurement. Revascularization was deferred in 6468 lesions and performed in 2165 lesions after FFR assessment. The primary end point was major adverse cardiac events (cardiac death, myocardial infarction, and repeat revascularization) at a median follow-up of 1.9 years and analyzed on a per-lesion basis. A marginal Cox model accounted for correlated data in patients with multiple lesions, and a model to predict per-lesion outcomes was adjusted for confounding factors.

RESULTS

For deferred lesions, the risk of major adverse cardiac events demonstrated a significant, inverse relationship with FFR (adjusted hazard ratio, 1.06; 95% confidence interval, 1.05-1.08; P<0.001). However, this relationship was not observed in revascularized lesions (adjusted hazard ratio, 1.00; 95% confidence interval, 0.98-1.02; P=0.70). For lesions with FFR ≥0.76, the risk of major adverse cardiac events was not significantly different between deferred and revascularized lesions. Conversely, in lesions with FFR ≤0.75, the risk of major adverse cardiac events was significantly lower in revascularized lesions than in deferred lesions (for FFR 0.71-0.75, adjusted hazard ratio, 0.47; 95% confidence interval, 0.24-0.89; P=0.021; for FFR ≤0.70, adjusted hazard ratio 0.47; 95% confidence interval, 0.26-0.84; P=0.012).

CONCLUSIONS

This large, prospective registry showed that the FFR value was linearly associated with the risk of cardiac events in deferred lesions. In addition, revascularization for coronary artery stenosis with a low FFR (≤0.75) was associated with better outcomes than the deferral, whereas for a stenosis with a high FFR (≥0.76), medical treatment would be a reasonable and safe treatment strategy.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01366404.

Factors associated with deferred lesion failure following fractional flow reserve assessment in patients with diabetes mellitus

OBJECTIVE

To explore the predictors of deferred lesion failure (DLF) in patients with diabetes mellitus (DM) and lesions with a fractional flow reserve (FFR) >0.80 and to examine whether a predictive relationship between negative FFR values (>0.80-1.00) and DLF exists.

BACKGROUND

DM is associated with rapidly progressive atherosclerosis and predictors of DLF in FFR negative lesions in this high-risk group are unknown.

METHODS

All DM patients who underwent FFR-assessment between 1/01/2010 and 31/12/2013 were included, and followed until 1/7/2015. Patients carrying ≥1 FFR negative lesion(s) were assessed for DLF, and multivariate models used to identify independent factors associated with DLF.

RESULTS

A total of 205 patients with 252 FFR >0.80 lesions were identified. At a mean follow-up of 3.1 ± 1.4 years, DLF occurred in 29/205 (14.1%) patients, 31/252 (12.3%) lesions. Using marginal Cox regression multivariate analysis, insulin requiring DM [HR 2.24 (95%CI; 1.01-4.95), P = 0.046] and prior revascularization [HR 2.70 (95%CI 1.21-6.01), P = 0.015] were identified as being associated with a higher incidence of DLF. Absolute FFR values in FFR negative lesions in DM patients are not predictive of DLF (receiver operating characteristics curve analysis: area under the curve: 0.57 ± 0.06, 95%CI 0.46-0.69).

CONCLUSIONS

In DM patients with FFR negative lesions, insulin requiring DM and prior revascularization are predictors for DLF. In contrast to non-DM patients, no predictive relationship between absolute negative FFR values (ranging >0.80-1.00) and the risk of DLF exists in DM patients. © 2017 Wiley Periodicals, Inc.

Prevalence and Clinical Significance of Discordant Changes in Fractional and Coronary Flow Reserve After Elective Percutaneous Coronary Intervention

BACKGROUND

Fractional flow reserve (FFR) and coronary flow reserve (CFR) are well-validated physiological indices; however, changes in FFR and CFR after percutaneous coronary intervention (PCI) remain elusive. We sought to evaluate these changes and to investigate whether physiological indices predict cardiac event-free survival after PCI.

METHODS AND RESULTS

Physiological assessment of 220 stenoses from 220 patients was performed before and after PCI. The changes in FFR and CFR were studied, and factors associated with CFR change were investigated. Follow-up data were collected to determine the predictor of cardiac events. CFR increase was found in 158 (71.8%) territories, and 62 (28.2%) presented a decrease, whereas FFR increased in all 220 (100%) territories. Pre- and post-PCI percentage diameter stenoses were 57.7±11.2% and 7.48±4.79%, respectively. Post-PCI CFR increase was associated with pre-PCI indices including low FFR, low CFR and high microvascular resistance, and post-PCI hyperemic coronary flow increase. Post-PCI CFR decrease was not associated with significant post-PCI hyperemic coronary flow increase. At a median follow-up of 24.3 months, adverse event-free survival was significantly worse in patients with lower pre-PCI CFR (log-rank test λ2=7.26; P=0.007). Cox proportional hazards analysis showed that lower pre-PCI CFR (hazard ratio 0.73; 95% CI 0.55-0.97; P=0.028) was an independent predictor of adverse cardiovascular events after PCI.

CONCLUSIONS

CFR decrease after PCI was not uncommon, and discordant change in FFR and CFR was associated with high pre-PCI CFR, low pre-PCI microvascular resistance, and no significant post-PCI hyperemic coronary flow increase. Pre-PCI CFR, not post-PCI physiological indices, may help identify patients who require adjunctive management strategy after successful PCI.

Fractional Flow Reserve-Guided Deferred Versus Complete Revascularization in Patients With Diabetes Mellitus

To assess the safety and efficacy of deferred versus complete revascularization using a fractional flow reserve (FFR)-guided strategy in patients with diabetes mellitus (DM), we analyzed all DM patients who underwent FFR-guided revascularization from January 1, 2010, to December 12, 2013. Patients were divided into 2 groups: those with ≥1 remaining FFR-negative (>0.80) medically treated lesions [FFR(-)MT] and those with only FFR-positive lesions (≤0.80) who underwent complete revascularization [FFR(+)CR] and were followed until July 1, 2015. The primary end point was the incidence of major adverse cardiovascular events (MACE), a composite of death, myocardial infarction (MI), target lesion (FFR assessed) revascularization, and rehospitalization for acute coronary syndrome. A total of 294 patients, 205 (69.7%) versus 89 (30.3%) in FFR(-)MT and FFR(+)CR, respectively, were analyzed. At a mean follow-up of 32.6 ± 18.1 months, FFR(-)MT was associated with higher MACE rate 44.0% versus 26.6% (log-rank p = 0.02, Cox regression-adjusted hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.21 to 3.33, p <0.01), and driven by both safety and efficacy end points: death/MI (HR 2.02, 95% CI 1.06 to 3.86, p = 0.03), rehospitalization for acute coronary syndrome (HR 2.06, 95% CI 1.03 to 4.10, p = 0.04), and target lesion revascularization (HR 3.38, 95% CI 1.19 to 9.64, p = 0.02). Previous MI was a strong effect modifier within the FFR(-)MT group (HR 1.98, 95% CI 1.26 to 3.13, p <0.01), whereas this was not the case in the FFR(+)CR group (HR 0.66, 95% CI 0.27 to 1.62, p = 0.37). Significant interaction for MACE was present between FFR groups and previous MI (p = 0.03). In conclusion, in patients with DM, particularly those with previous MI, deferred revascularization is associated with poor medium-term outcomes. Combining FFR with imaging techniques may be required to guide our treatment strategy in these patients with high-risk, fast-progressing atherosclerosis.