Comparison of medical treatment and coronary revascularization in patients with moderate coronary lesions and borderline fractional flow reserve measurements

Prognostic differences between physiology-guided percutaneous coronary intervention and optimal medical therapy in coronary artery disease: A systematic review and meta-analysis

Background

Intracoronary physiology, particularly fractional flow reserve (FFR), has been used as a guide for revascularization for patients with coronary artery disease (CAD). The optimal treatment in the physiological grey-zone area has been unclear and remains subject to ongoing debate.

Methods

We conducted a systematic review of randomized controlled trials and observational studies comparing the prognostic effect of percutaneous coronary revascularization (PCI) and optimal medical therapy (OMT) in patients with CAD. Studies were identified by medical literature databases. The outcomes of interest were major adverse cardiac events (MACE) and its components, death, myocardial infarction (MI), and repeat revascularization.

Results

A total of 16 studies with 27,451 patients were included. The pooled analysis demonstrated that PCI was associated with a prognostic advantage over OMT in patients with FFR value ≤0.80 (RR: 0.64, 95 % CI: 0.45-0.90, p < 0.01). Patients with an FFR value >0.80 were shown to benefit more from OMT (RR 1.38, 95 % CI 1.24-1.53, p < 0.01). The analysis also showed that there was no significant difference in MACE in the grey-zone area (FFR 0.75-0.80) (RR 0.64, 95 % CI: 0.35-1.16, p = 0.14), but a significant reduction in repeat revascularization (RR 0.54, 95 % CI, 0.31-0.91, p < 0.01) when patients were treated with PCI.

Conclusions

Among patients with CAD and FFR values >0.80, OMT was associated with favorable outcomes over PCI in reducing the risk of MACE. However, among patients with FFR values ≤0.80, revascularization was superior in terms of reducing MACE. The available evidence supports the guideline-recommended use of an FFR cut-off of ≤0.80.

Relationship between adenosine A2a receptor polymorphism rs5751876 and fractional flow reserve during percutaneous coronary intervention

Fractional flow reserve (FFR) assessed during adenosine-induced maximal hyperemia has emerged as a useful tool for the guidance of percutaneous coronary interventions (PCI). However, interindividual variability in the response to adenosine has been claimed as a major limitation to the use of adenosine for the measurement of FFR, carrying the risk of underestimating the severity of coronary stenoses, with potential negative prognostic consequences. Genetic variants of the adenosine receptor A2a (ADORA2A gene), located in the coronary circulation, have been involved in the modulation of the hyperemic response to adenosine. However, no study has so far evaluated the impact of the single nucleotide polymorphism rs5751876 of ADORA2A on the measurement of FFR in patients undergoing percutaneous coronary intervention that was, therefore, the aim of our study. We included patients undergoing coronary angiography and FFR assessment for intermediate (40-70%) coronary lesions. FFR measurement was performed by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440 μg, with dose doubling at each step). Restriction fragment length polymorphism (RFLP) analysis was performed to assess the presence of rs5751876 C>T polymorphism of ADORA2a receptor. We included 204 patients undergoing FFR measurement of 231 coronary lesions. A total of 134 patients carried the polymorphism (T allele), of whom 41 (30.6%) in homozygosis (T/T).Main clinical and angiographic features did not differ according to ADORA2A genotype. The rs5751876 C>T polymorphism did not affect mean FFR values (p = 0.91), the percentage of positive FFR (p = 0.54) and the duration of maximal hyperemia. However, the time to recovery to baseline FFR values was more prolonged among the T-allele carriers as compared to wild-type patients (p = 0.04). Based on these results, in patients with intermediate coronary stenoses undergoing FFR assessment with adenosine, the polymorphism rs5751876 of ADORA2A does not affect the peak hyperemic response to adenosine and the results of FFR. However, a more prolonged effect of adenosine was observed in T-carriers.

Percutaneous coronary intervention versus medical therapy in patients with angina and grey-zone fractional flow reserve values: a randomised clinical trial

INTRODUCTION

There is conflicting evidence regarding the benefits of percutaneous coronary intervention (PCI) in patients with grey zone fractional flow reserve (^GZFFR artery) values (0.75-0.80). The prevalence of ischaemia is unknown. We wished to define the prevalence of ischaemia in ^GZFFR artery and assess whether PCI is superior to optimal medical therapy (OMT) for angina control.

METHODS

We enrolled 104 patients with angina with 1:1 randomisation to PCI or OMT. The artery was interrogated with a Doppler flow/pressure wire. Patients underwent Magnetic Resonance Imaging (MRI) with follow-up at 3 and 12 months. The primary outcome was angina status at 3 months using the Seattle Angina Questionnaire (SAQ).

RESULTS

104 patients (age 60±9 years), 79 (76%) males and 79 (76%) Left Anterior Descending (LAD) stenoses were randomised. Coronary physiology and SAQ were similar. Of 98 patients with stress perfusion MRI data, 17 (17%) had abnormal perfusion (≥2 segments with ≥25% ischaemia or ≥1 segment with ≥50% ischaemia) in the target ^GZFFR artery. Of 89 patients with invasive physiology data, 26 (28%) had coronary flow velocity reserve <2.0 in the target ^GZFFR artery. After 3 months of follow-up, compared with patients treated with OMT only, patients treated by PCI and OMT had greater improvements in SAQ angina frequency (21 (28) vs 10 (23); p=0.026) and quality of life (24 (26) vs 11 (24); p=0.008) though these differences were no longer significant at 12 months.

CONCLUSIONS

Non-invasive evidence of major ischaemia is uncommon in patients with ^GZFFR artery. Compared with OMT alone, patients randomised to undergo PCI reported improved symptoms after 3 months but these differences were no longer significant after 12 months.

TRIAL REGISTRATION NUMBER

NCT02425969.

Deferred vs. performed revascularization for coronary stenosis with grey-zone fractional flow reserve values: data from the IRIS-FFR registry

Aims

The optimal fractional flow reserve (FFR) cut-off value for revascularization is debated. We evaluated the prognosis for deferred and performed revascularization in coronary stenosis with FFR values in the grey zone (0.75-0.80).

Methods and results

This study included 1334 native coronary stenosis with grey-zone FFR values in 1334 patients from the prospective multicentre Interventional Cardiology Research In-cooperation Society Fractional Flow Reserve registry. Revascularization was deferred for 683 patients (deferred group) and performed for 651 (performed group). The primary outcome, a composite of death, target-vessel myocardial infarction (MI), and target vessel revascularization (TVR) occurred in 55 (8.1%) patients in the deferred group and 55 (8.4%) in the performed group [adjusted hazard ratio (aHR) 1.05, 95% confidence interval (CI) 0.67-1.66; P = 0.79] during a median follow-up of 2.9 years (interquartile range 1.5-4.1 years). Overall mortality and spontaneous MI did not differ between the groups (mortality 2.5% vs. 2.0%; aHR 0.82, 95% CI 0.34-2.00; P = 0.66; spontaneous MI 0.7% vs. 0.5%; aHR 1.85, 95% CI 0.35-9.75; P = 0.47). Myocardial infarction was significantly higher in the performed group (0.7% vs. 3.2%; aHR 0.27, 95% CI 0.09-0.80; P = 0.02) mainly because of a higher risk of periprocedural MI. Target vessel revascularization was significantly higher in the deferred group (5.7% vs. 3.7%; aHR 2.17, 95% CI 1.17-4.02; P = 0.01).

Conclusion

For coronary stenosis with grey-zone FFR, revascularization was not associated with better clinical outcomes. The higher likelihood of periprocedural MI with revascularization was offset by the higher likelihood of TVR with deferral.

Trial registration

Clinicaltrials.gov identifier: NCT01366404.

Outcomes With Deferred Versus Performed Revascularization of Coronary Lesions With Gray-Zone Fractional Flow Reserve Values

BACKGROUND

Management of coronary lesions with fractional flow reserve values in the gray zone (0.75-0.80) remains controversial due to conflicting data on the performance versus deferral of revascularization.

METHODS

We performed a systematic review and meta-analysis of 7 observational studies including 2683 patients that compared the outcomes of deferred versus performed revascularization of coronary lesions with gray-zone fractional flow reserve values.

RESULTS

During a mean follow-up of 31±9 months, the incidence of major adverse cardiovascular events (12.54 % versus 11.25%; odds ratio [OR], 1.64 [95% CI, 0.78-3.44]; P=0.19, I2=84%), cardiac mortality (1.25% versus 0.72%; OR, 1.78 [95% CI, 0.58-5.46]; P=0.31, I2=18%), and myocardial infarction (1.28% versus 2.66%; OR, 0.79 [95% CI, 0.22-2.79]; P=0.71, I2=65%) was similar with deferral versus performance of revascularization in coronary lesions with gray-zone fractional flow reserve. Deferral of revascularization was associated with a higher incidence of target vessel revascularization (9.12% versus 5.78%; OR, 1.85 [95% CI, 1.03-3.33]; P=0.04, I2=62%). When the analysis was limited only to studies that used percutaneous coronary intervention for revascularization, deferred revascularization remained associated with a higher risk of target vessel revascularization (18% versus 7.3%; OR, 3.04 [95% CI, 1.53-6.02]; P<0.001) and was associated with a higher risk of major adverse cardiovascular event (23.2% versus 13.4%; OR, 3.38 [95% CI, 1.92-5.95]; P<0.001).

CONCLUSIONS

In lesions with gray-zone fractional flow reserve, revascularization was associated with a similar incidence of major adverse cardiovascular event but a lower incidence of target vessel revascularization over a mean follow-up of approximately 2.5 years.

CLINICAL TRIAL REGISTRATION

URL: https://www.crd.york.ac.uk/prospero/. Unique identifier: CRD42019128076.

Prospective Randomized Comparison of Fractional Flow Reserve Versus Optical Coherence Tomography to Guide Revascularization of Intermediate Coronary Stenoses: One-Month Results

Background Fractional flow reserve (FFR) and optical coherence tomography (OCT) may help both in assessment and in percutaneous coronary intervention optimization of angiographically intermediate coronary lesions. We designed a prospective trial comparing the clinical and economic outcomes associated with FFR or OCT in angiographically intermediate coronary lesions. Methods and Results Three hundred fifty patients with angiographically intermediate coronary lesions (n=446) were randomized to FFR or OCT guidance. In the FFR arm, percutaneous coronary intervention was performed if FFR was ≤0.80 aiming for a postprocedure FFR >0.90. In the OCT arm, percutaneous coronary intervention was performed if percentage of area stenosis was ≥75% or 50% to 75% with minimal lumen area <2.5 mm2 or plaque ulceration. Costs, angina frequency, and major adverse cardiac events were assessed at 1 month and at 13 months. We present early data at 1 month consistent with a prespecified analysis of secondary end points. Patients randomized to FFR, as compared with OCT, were significantly more commonly managed with medical therapy alone (67.7% versus 41.1%; P<0.001), required less contrast media (245±137 versus 280±129 mL; P=0.004), and exhibited a lower occurrence of contrast-induced acute kidney injury (1.7% versus 8.6%; P=0.034). At 1 month, in comparison to FFR, OCT was associated with increased total costs (2831±1288 versus 4292±3844 euros/patient; P<0.001) whereas occurrence of major adverse cardiac events or significant angina was similar. Conclusions In patients with angiographically intermediate coronary lesions, a functional guidance by FFR, as compared with OCT, increased the rate of patients treated with medical therapy alone. This translated into a significant reduction in administered contrast, contrast-induced acute kidney injury, and total costs at 1 month with FFR. Clinical Trial Registration URL: http://www.clinicaltrialsgov. Unique identifier: NCT01824030.

Deferral Versus Performance of Revascularization for Coronary Stenosis With Grey Zone Fractional Flow Reserve Values: A Systematic Review and Meta-Analysis

We searched PubMed, EMBASE, Cochrane Library, and Web of Science for studies using fractional flow reserve (FFR) to determine whether revascularization should be performed or deferred for patients with coronary stenosis and grey zone FFR. Meta-analysis was performed using the generic inverse variance method, and hazard ratios (HR) were synthesized with a random-effects model. Of 2766 records, 7 nonrandomized studies including 2683 patients were selected. The pooled results demonstrated, during a median follow-up of 32 months, that revascularization significantly reduced the risk of major adverse cardiac events (MACE; 7 studies: HR [95% confidence interval, CI]: 0.65 [0.45-0.93], P = .02) and target vessel revascularization (TVR; 4 studies: HR [95% CI]: 0.52 [0.36-0.76], P < .01). Whereas revascularization was not significantly superior in terms of all-cause death (3 studies: HR [95% CI]: 0.56 [0.26-1.22], P = .14), cardiac death (2 studies: HR [95% CI]: 0.57 [0.16-2.01], P = .38), myocardial infarction (MI; 4 studies: HR [95% CI]: 1.03 [0.26-4.03]), and all-cause death or MI (3 studies: HR [95% CI]: 0.66 [0.20-2.19], P = .50). Therefore, revascularization appeared to be superior to deferral for patients with grey zone FFR in MACE and TVR, while hard end points did not show such significance. This work was registered in PROSPERO (CRD42019118432).

Optimal Treatment Strategy for Coronary Artery Stenoses with Grey Zone Fractional Flow Reserve Values. A Systematic Review and Meta-Analysis

OBJECTIVES

We conducted a review and meta-analysis of published data to compare revascularization to deferral strategy for coronary lesions with grey zone fractional flow reserve (FFR).

BACKGROUND

Optimal treatment for coronary stenoses with FFR values between 0.75 and 0.80, the so-called grey zone, remains a matter of debate.

METHODS

We included all studies evaluating revascularization versus deferral for lesions with grey zone FFR. The primary outcome was study-defined major adverse cardiac events (MACE). Secondary outcomes were the composite of death or MI and target vessel revascularization (TVR). A total of 2362 patients were included, of whom 1181 underwent revascularization (revascularization group) and 1181 received medical treatment only (deferral group).

RESULTS

After a mean follow-up period of 2.4 years, no difference was found for the primary outcome of the study-defined MACE between the two groups [RR = 1.33 (0.73-2.44), p = 0.35]. In addition, there was no difference for the secondary outcomes of death or MI and TVR between the two groups [RR = 1.39 (0.56-3.47), p = 0.48 and RR = 1.49 (0.89-2.51), p = 0.13, respectively].

CONCLUSIONS

In this meta-analysis revascularization of coronary stenoses with grey zone FFR showed no advantage over a deferral strategy in terms of study-defined MACE. Case by case judgment should be implemented to guide treatment in this special subset of patients.

Comparison of clinical outcomes following percutaneous coronary intervention versus optimal medical therapy based on gray-zone fractional flow reserve in stable angina patients with intermediate coronary artery stenosis (COMFORTABLE prospective study): Study protocol for a multicenter randomized controlled trial

Background

Even in the current drug-eluting stent era, revascularization for coronary stenosis with fractional flow reserve (FFR) between 0.75 and 0.80, the so-called “gray zone,” is a matter of debate. Previous studies have reported conflicting results regarding outcomes of revascularization versus deferral for coronary stenosis when FFR values are in the gray zone, but these studies have had differing designs and populations. We therefore will investigate whether medical therapy plus percutaneous coronary intervention (PCI) is superior to medical therapy alone in reducing major cardiovascular events in patients presenting with coronary stenosis with gray zone FFR values.

Methods/design

This is a prospective, multicenter, open-label, parallel group, randomized, controlled, superiority study. A total of 410 eligible participants will be recruited and randomized to either the medical therapy plus PCI group or the medical therapy alone group. The primary endpoint is 1-year major adverse cardiac events (MACEs), defined as a combined endpoint of all-cause death, nonfatal myocardial infarction (MI), or unplanned target vessel revascularization (TVR). Secondary endpoints include MACE at 2 and 5 years. Moreover, each individual component of the primary endpoint, cardiovascular death, target vessel-related and non-target vessel-related MI, all MI, clinically driven TVR or non-TVR, all revascularization, stent thrombosis, and angina symptom status will be evaluated at 1, 2, and 5 years.

Discussion

This is the first prospective, multicenter, randomized, controlled study to investigate the superiority of medical therapy plus PCI over medical therapy by itself in reducing major cardiovascular events in patients presenting with coronary stenosis with “gray zone” FFR values. The results will help interventional cardiologists in making revascularization decisions regarding coronary stenosis with gray zone FFR values.

Trial registration

University Hospital Medical Information Network Clinical Trials Registry, UMIN000031526. Registered on 1 March 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3182-1) contains supplementary material, which is available to authorized users.

Intravascular ultrasound characteristics in patients with intermediate coronary lesions and borderline fractional flow reserve measurements

Revascularization of borderline fractional flow reserve (FFR) is controversial and the morphologic characteristics of borderline FFR lesions are not well known. The objective of this study was to determine the intravascular ultrasound (IVUS) characteristics in intermediate coronary lesions with borderline FFR in patients with intermediate coronary artery stenosis (40%-70% diameter stenosis).Both IVUS and FFR were performed in a total of 228 left anterior descending arteries. We divided them into 3 groups by FFR value: ischemic (n = 46, FFR < 0.75), borderline (n = 71, FFR 0.75 to ≤0.80), and non-ischemic (n = 111, FFR > 0.80). We compared the IVUS parameters, including minimum lumen area, lesion length, plaque burden, and volumetric analysis among the 3 groups.In the IVUS analysis, the minimum lumen area was smaller (2.5 ± 0.6 vs. 2.7 ± 0.7 vs. 3.4 ± 1.2 mm, P < .001); lesion length was longer (23.6 ± 8.4 vs. 23.6 ± 7.4 vs. 17.4 ± 6.8 mm, P < .001); plaque burden was larger (76.1 ± 9.6 vs. 73.9 ± 7.5 vs. 69.8 ± 9.5%, P < .001); plaque volume was larger (173.0 ± 78.3 vs. 167.7 ± 75.0 vs. 129.5 ± 79.1 mm, P < .01); and percent atheroma volume was larger (57.9 ± 7.5 vs. 57.6 ± 6.6 vs. 53.9 ± 8.0%, P < .01) in the ischemic and borderline groups compared with the non-ischemic group, respectively. However, post-hoc analyses showed there were no significant differences between the ischemic and borderline group for all IVUS parameters.There were no differences in IVUS characteristics between borderline and functionally significant FFR, but the amount of atheromatous plaque was more severe in these 2 groups than in the non-ischemic group.

Past, Present and Future of Coronary Physiology

It is well known that the apparent significant coronary stenosis on angiography sometimes does not cause significant ischemia, and vice versa. For this reason, decision-making based on coronary physiology is becoming more and more important. Fractional flow reserve (FFR), which has emerged as a useful tool to determine which lesions need revascularization in the catheterization laboratory, now has a class IA indication in the European Society of Cardiology guidelines. More recently, the instantaneous wave-free ratio, which is considered easier to use than FFR, has been graded as equivalent to FFR. This review discusses the concepts of FFR and instantaneous wave-free ratio, current evidence supporting their use, and future directions in coronary physiology.

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.

Clinical Relevance of Coronary Fractional Flow Reserve: Art-of-state

Objective:

The objective was to delineate the current knowledge of fractional flow reserve (FFR) in terms of definition, features, clinical applications, and pitfalls of measurement of FFR.

Data Sources:

We searched database for primary studies published in English. The database of National Library of Medicine (NLM), MEDLINE, and PubMed up to July 2014 was used to conduct a search using the keyword term “FFR”.

Study Selection:

The articles about the definition, features, clinical application, and pitfalls of measurement of FFR were identified, retrieved, and reviewed.

Results:

Coronary pressure-derived FFR rapidly assesses the hemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterization laboratory. The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.

Conclusions:

FFR is a valuable tool to determine the functional significance of coronary stenosis. It combines physiological and anatomical information, and can be followed immediately by percutaneous coronary intervention (PCI) if necessary. The technique of FFR measurement can be performed easily, rapidly, and safely in the catheterization laboratory. By systematic use of FFR in dubious stenosis and multi-vessel disease, PCI can be made an even more effective and better treatment than it is currently. The current clinical evidence for FFR should encourage cardiologists to use this tool in the catheterization laboratory.

Long-term outcome of intravascular ultrasound application in patients with moderate coronary lesions and grey-zone fractional flow reserve

OBJECTIVE

This study aimed to assess the long-term outcome of intravascular ultrasound (IVUS) application in patients with a fractional flow reserve (FFR) of 0.75-0.80.

BACKGROUND

Scientifically evaluating anatomical structures is vital because structure influences both physiological function and decision-making in moderate coronary lesions, especially for those with an FFR of 0.75-0.80.

MATERIALS AND METHODS

Patients (n=128) were divided into three groups based on treatment: the drug control group (n=40), the IVUS-percutaneous coronary intervention (PCI) group (n=40) and the IVUS-drug group (n=48). A PCI was performed when a patient had a minimum lumen area less than 4 mm(2) and a plaque burden of 70% or greater. Major adverse clinical events were defined as cardiac death, nonfatal myocardial infarction, target vessel revascularization, including PCI or coronary artery bypass grafting, and unstable angina, all of which were also evaluated during follow-up.

RESULTS

Kaplan-Meier curves indicated that the incidence of major adverse clinical events did not differ between the IVUS-PCI and IVUS-drug groups (5 vs. 6.3%, P=0.810), but the levels in both of these groups significantly decreased compared with the drug control group (5 vs. 22.5%, P=0.024, and 6.5 vs. 22.5%, P=0.026, respectively).

CONCLUSION

The long-term outcome of the application of IVUS in patients with a grey-zone FFR of 0.75-0.80 was superior to that of patients who were treated only with drugs without IVUS measurement. Patients with a grey-zone FFR should receive an individualized treatment strategy according to their IVUS parameters. Patients with the same FFR values may require different treatment strategies.

The Impact of Fractional Flow Reserve on Revascularization

Introduction

Fractional flow reserve (FFR) is recommended by society guidelines for assessment of the hemodynamic significance of intermediate coronary lesions when non-invasive evidence of myocardial ischemia is unavailable. However, the prevalence of FFR usage in current practice and how FFR values impact revascularization decisions are not well known.

Methods

At a single-center Veterans Administration Hospital, all subjects referred for coronary angiography for any indication from the period from May 2012 until January 2014 were prospectively entered into a database. FFR was measured in all intermediate coronary lesions (30–70% stenosis). Based on the FFR results, the lesions were categorized into 3 different groups: FFR > 0.80 (non-ischemic), FFR 0.75–0.80 (gray zone), and FFR < 0.75 (ischemic).

Results

A total of 1482 cardiac catheterizations were performed during the study period. FFR was performed in 347 (23%) of these procedures. The total numbers of intermediate coronary lesions evaluated with FFR were 429. The mean FFR value was 0.79 (median = 0.80; interquartile range 0.64–0.96). Among 211 non-ischemic lesions, revascularization was deferred in 201 (95%). In the gray-zone group (73 lesions), 35 (48%) lesions were treated with percutaneous coronary intervention (PCI), 11 (15%) lesions were referred for coronary artery bypass grafting surgery (CABG), and 27 (37%) lesions were treated medically. In the ischemic group (145 lesions), 82 (57%) lesions were treated with PCI, 41 (28%) lesions were referred for CABG, and 22 (15%) lesions were treated medically.

Conclusion

At a Veterans Administration Hospital, FFR was performed in approximately one out of four total catheterizations. FFR documented lack of ischemia in about half of the intermediate coronary lesions, and thus reduced the need for many revascularization procedures.

Electronic supplementary material

The online version of this article (doi:10.1007/s40119-015-0051-1) contains supplementary material, which is available to authorized users.

Advances in coronary physiology

Pressure-wire technology, most typically fractional flow reserve (FFR), has provided interventional cardiologists with a means of determining the physiological importance of a stenosis during angiography. There has been renewed interest in coronary physiology in the light of guideline recognition, ongoing clinical research and new technologies changing the paradigm of how assessment is performed in the catheter laboratory. We reflect on FFR, with regards the potential effects of changing hemodynamics on FFR and the latest evidence with regards to outcomes. We also review the instantaneous wave-free ratio (iFR), a new pressure-only index, measured at rest, that is under active evaluation in several international randomized controlled trials. We review the accumulated evidence and discuss the important physiological concepts between pressure and flow that underlie the approach to using resting indices. Finally we investigate future developments, including physiological mapping with iFR-Pullback and the potential to predict the hemodynamic effect of stenting.

Long-term outcome after deferral of revascularization in patients with intermediate coronary stenosis and gray-zone fractional flow reserve

BACKGROUND

A strategy of deferred percutaneous coronary intervention for coronary stenosis with fractional flow reserve (FFR) 0.75-0.80, termed the gray zone, remains a matter of debate. The aim of this study was to assess the safety of deferring revascularization for patients with FFR 0.75-0.80 compared with those with FFR >0.80.

METHODS AND RESULTS

We assessed 3-year clinical outcome in 150 patients with angiographically intermediate stenosis who had revascularization deferred on the basis of FFR ≥ 0.75 (FFR 0.75-0.80, n=56; FFR >0.80, n=94). Target vessel failure (TVF), defined as a composite of cardiac death, target vessel-related myocardial infarction (MI), and ischemia-driven target vessel revascularization (TVR) was evaluated during follow-up. Cardiac death was observed in 1 patient with FFR 0.75-0.80. There was no target vessel-related MI in either group. The incidence of ischemia-driven TVR was higher in patients with FFR 0.75-0.80 than in those with FFR >0.80 (14% vs. 3%, P=0.020). TVF-free survival was significantly worse for the patients with FFR 0.75-0.80 than those with FFR >0.80 (hazard ratio, 5.2; 95% confidence intervals: 1.4-19.5; P=0.015).

CONCLUSIONS

Patients with FFR 0.75-0.80 were at higher risk of TVF mainly due to TVR than those with FFR >0.80.

Outcomes of coronary stenoses deferred revascularization for borderline versus nonborderline fractional flow reserve values

Current evidence supports deferral of revascularization for lesions with fractional flow reserve (FFR) values >0.80. The natural history after deferral of revascularization of lesions with borderline FFR values is unknown. This study evaluated the outcomes of patients after deferred revascularization of coronary stenoses based on a borderline FFR value. We retrospectively studied 720 patients with 881 intermediate-severity coronary stenoses who underwent FFR assessment from October 2002 to July 2010 and were deferred revascularization. Patients were divided into gray zone (0.75 to 0.80), borderline (0.81 to 0.85), and nonborderline (>0.85) FFR groups. Any subsequent percutaneous coronary intervention or coronary artery bypass grafting of a deferred stenosis during follow-up was classified as a deferred lesion intervention (DLI). Patient and/or lesion characteristics and clinical outcomes were compared between the FFR groups using univariate and propensity score-adjusted inverse probability of weighting Cox proportional hazards analyses. During a mean follow-up of 4.5 ± 2.1 years, 157 deferred lesions (18%) underwent DLI by percutaneous coronary intervention (n = 117) or coronary artery bypass grafting (n = 40). No statistically significant differences were observed in clinical outcomes between the gray zone and borderline FFR groups. Lesions with a borderline FFR were associated with a significantly higher risk of DLI compared with lesions with nonborderline FFR values (hazard ratio 1.63, 95% confidence interval 1.14 to 2.33, p = 0.007). Lesions deferred revascularization because of a borderline FFR (0.81 to 0.85) were associated with a higher risk of DLI compared with lesions with a nonborderline FFR (>0.85). Further study is needed to determine the optimal management of coronary stenoses with a borderline FFR value.

Fractional flow reserve or optical coherence tomography guidance to revascularize intermediate coronary stenosis using angioplasty (FORZA) trial: study protocol for a randomized controlled trial

BACKGROUND

The management of patients with angiographically intermediate coronary lesions is a major clinical issue. Fractional flow reserve provides validated functional insights while optical coherence tomography provides high resolution anatomic imaging. Both techniques may be applied to guide management in case of angiographically intermediate coronary lesions. Moreover, these techniques may be used to optimize the result of percutaneous coronary intervention. We aim to compare the clinical and economic impact of fractional flow reserve versus optical coherence tomography guidance in patients with angiographically intermediate coronary lesions.

METHODS/DESIGN

Patients with at least one angiographically intermediate coronary lesion will be randomized (ratio 1:1) to fractional flow reserve or optical coherence tomography guidance. In the fractional flow reserve arm, percutaneous coronary intervention will be performed if fractional flow reserve value is ≤0.80, and will be conducted with the aim of achieving a post-percutaneous coronary intervention fractional flow reserve target value of ≥0.90. In the optical coherence tomography arm, percutaneous coronary intervention will be performed if percentage of area stenosis (AS%) is ≥75% or 50 to 75% with minimal lumen area <2.5 mm2, or if a major plaque ulceration is detected. In case of percutaneous coronary intervention, optical coherence tomography will guide the procedure in order to minimize under-expansion, malapposition, and edge dissections.Cost load and clinical outcome will be prospectively assessed at one and thirteen months. The assessed clinical outcome measures will be: major cardiovascular events and occurrence of significant angina defined as a Seattle Angina Questionnaire score <90 in the angina frequency scale.

DISCUSSION

The FORZA trial will provide useful guidance for the management of patients with coronary artery disease by prospectively assessing the use of two techniques representing the gold standard for functional and anatomical definition of coronary plaques.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01824030.

Fractional flow reserve: an updated review

Revascularization of ischemia-producing coronary lesions is widely used in the management of coronary artery disease. However, some coronary lesions appear significant on the conventional angiogram when they are truly non-flow limiting. For this reason, it is becoming increasingly important to determine the coronary physiology. Fractional flow reserve (FFR) has emerged as a useful tool to determine the lesions that require revascularization. Measurement of FFR during invasive coronary angiography now has a class IA indication from the European Society of Cardiology for identifying hemodynamically significant coronary lesions when noninvasive evidence of myocardial ischemia is unavailable. Current data on FFR can be broadly classified into studies that compare the diagnostic accuracy of FFR measurement compared with other noninvasive modalities and studies that test treatment strategies of patients with intermediate coronary stenoses using a threshold value for FFR and that have clinical outcomes as endpoints. In this review, we will discuss the concept of FFR, current evidence supporting its usage, and future perspectives.

Translesional pressure ratio predicts technical outcome and patency in angioplasty on outflow stenosis of hemodialysis graft

PURPOSE

Translesional pressure ratio (TLPR) indicating fractional flow reserve has been applied to physiological assessment of moderate coronary stenosis. The role of TLPR in hemodialysis (HD) patients with arteriovenous graft (AVG) outflow stenosis undergoing percutaneous transluminal angioplasty (PTA) is unclear. The purpose of the study was to assess the validation of TLPR in such patients undergoing PTA.

METHODS

Patients with pure AVG outflow stenosis confirmed by angiography were prospectively enrolled. A TLPR defined as a ratio of the mean pressure downstream to the lesion(s) to the vein-sided intragraft pressure was measured using a catheter pullback method. Relationship among TLPR, angiographic result and clinical outcome within 6 months was detected.

RESULTS

Of 65 PTAs, the post-PTA TLPR significantly increased (from 0.28±0.10 to 0.50±0.11; p<0.0001). A significantly greater pre-PTA TLPR was observed in the simple lesions at baseline compared with the complex lesions (0.32±0.09 vs. 0.20±0.06; p<0.0001). Post-PTA TLPR ≥0.5 was powerfully related to angiographic success (p<0.0001). The group with angiographic success plus post-PTA TLPR ≥0.5 had a longer PTA-free patency (208.7±188.7 vs. 109.8±67.7 days; p=0.013) compared with that with angiographic nonsuccess plus post-PTA TLPR <0.5.

CONCLUSIONS

Our data show that TLPR correlates well with lesion properties and angiographic results, and helps predict following unassisted patency. The study suggests TLPR as a hemodynamic indicator during PTA.

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

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

Long-term clinical outcomes after deferral of percutaneous coronary intervention of intermediate coronary stenoses based on coronary pressure-derived fractional flow reserve

Coronary pressure-derived fractional flow reserve (FFR) has been used to evaluate functional severity of coronary artery stenoses. The cut-off point of 0.75 was considered to be the indication for percutaneous coronary intervention (PCI). In this study, we examined the prognosis of patients in whom PCI was deferred because the lesion was not significant by FFR (≥0.75). We measured FFR of 44 patients (50 lesions with angiographically intermediate stenoses by pressure wire between 2002 and 2009. Out of 44 patients (50 lesions), functionally non-significant stenoses with FFR≥0.75 were 29 patients (33 lesions) and PCI was deferred. In the remaining 15 patients (17 lesions), FFR was <0.75 and PCI was performed. Patients were followed up for an average period of 53 months with endpoints of major adverse cardiac events (MACE; cardiac death, acute coronary syndrome, PCI, and coronary artery bypass grafting). The rate of MACE was 2/29 (6.9%) in patients with FFR≥0.75 and 2/15 (13.3%) in those with FFR<0.75, and it was not statistically different between the two groups. Since long-term clinical outcomes after deferral of PCI of intermediate coronary stenoses based on FFR were excellent (annual event rate 1.6%/year), FFR is a useful index to judge the indication of PCI and risk-stratify patients for MACE.

Patients with coronary stenosis and a fractional flow reserve of ≥0.75 measured in daily practice at the VU University Medical Center

Objectives. The aim of this study was to analyse the rate of major adverse clinical events in patients with coronary artery disease and a fractional flow reserve (FFR) of ≥0.75 and deferred for coronary intervention in daily practice. Methods. From 1 January to 31 December 2006, FFR measurement was initiated in 122 patients (5%) out of 2444 patients referred for coronary angiography. In two patients FFR measurement failed and in one patient the FFR value could no longer be traced in the documents. Thus, 119 patients (84 men, 64 years, range 41-85) were included in the evaluation (145 lesions). Major adverse clinical events (death, myocardial infarction, percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG)) and the presence of angina were evaluated at follow-up. Furthermore a cost-effectiveness analysis was performed.Results. In 93 patients (76%) the FFR value was ≥0.75. Seventy of these 93 patients (76%) were treated with medication alone or underwent PCI for a different lesion (medical treatment group). Average duration of follow-up of all 119 patients was 22 months (range 4 days to 30 months). In the medical treatment group seven patients (10%) experienced a major adverse clinical event related to the FFR-evaluated lesion during follow-up. In this study population, the use of FFR measurement is cost-reducing provided that at least 65% of the patients in the medical treatment group has had a PCI with stent implantation when the use of FFR measurement is impossible. In this case, the decision to use PCI with stent implantation is purely based on the angiogram. Conclusions. In patients with a coronary stenosis based on visual assessment and an FFR of ≥0.75 deferral of PCI or CABG is safe in daily clinical practice and saves money. (Neth Heart J 2010;18:402-7.).

Clinical outcome following conservative vs revascularization therapy in patients with stable coronary artery disease and borderline fractional flow reserve measurements

BACKGROUND

Fractional flow reserve (FFR) measurements in the so-called gray-zone range of > or = 0.75 and < or =0.80 are associated with uncertainty concerning the guidance of patient therapy. It is unclear whether any difference in clinical outcome exists when revascularization treatment of FFR-evaluated lesions in this borderline range is deferred or performed. The objective of this study is to compare the clinical outcome of these patients with respect to their recommended treatment strategy.

METHODS

Out of a single center database of 900 consecutive patients with stable coronary artery disease, 97 patients with borderline FFR measurements were identified and included in the study. The rate of major adverse cardiac events (MACE; cardiac death, myocardial infarction (MI), coronary revascularization) and the presence of angina were evaluated at follow-up.

RESULTS

A total of 48 patients were deferred from revascularization and 49 patients underwent revascularization. There was no difference in risk profile between these groups. At a mean follow-up of 24+/-16 months, event-free survival in the deferred group was significantly better regarding overall MACE, combined rate of cardiac death, and MI, as well as MACE related to the FFR-evaluated vessel. No difference with regard to the presence of angina was observed.

CONCLUSIONS

Patients with coronary lesions in the borderline FFR range can be deferred from revascularization without putting them at increased risk for major adverse events. Revascularization may be considered in the course of therapy on an individual basis if typical angina persists or worsens despite maximal medical treatment.

Usefulness of coronary fractional flow reserve measurements in guiding clinical decisions in intermediate or equivocal left main coronary stenoses

The objectives of this study were to evaluate the usefulness of fractional flow reserve (FFR) measurements to guide the clinical decision in patients with intermediate left main coronary artery (LMCA) stenosis and to determine the predictors of major adverse cardiac events (MACE) -- cardiac death, myocardial infarction, coronary revascularization -- in such cases; 142 consecutive patients with intermediate LMCA stenosis (mean percent diameter stenosis 42 +/- 13%) were included. All patients underwent FFR measurement after intracoronary administration of adenosine at a dose > or =30 microg. The clinical decisions were based on FFR as follows: coronary revascularization was recommended if FFR was <0.75, medical treatment if FFR was >0.80, and individualized decision based on additional clinical data if FFR was between 0.75 and 0.80. Mean FFR was 0.81 +/- 0.09 after the administration of 176 +/- 99 microg of adenosine. Based on FFR results, 60 patients (42%) underwent coronary revascularization, and 82 patients (58%) received medical treatment. At 14 +/- 11 months follow-up, the incidence of MACE related to the LMCA stenosis was 13% in the medical treatment group and 7% in the revascularization group (p = 0.27). The incidence of cardiac death or myocardial infarction was 6% in the medical treatment group and 7% in the revascularization group (p = 0.70). In the medical treatment group, with MACE had received a lower dose of intracoronary adenosine (86 +/- 57 vs 167 +/- 102 microg; odds ratio 1.39 for each decrease of 30 microg of intracoronary adenosine, 95% confidence interval 1.02 to 1.89) and more frequently had diabetes (55% vs 21%; odds ratio 4.40, 95% confidence interval 1.17 to 16.42). In conclusion, FFR measurement is helpful in guiding the decision whether to revascularize patients with intermediate LMCA stenosis. However, patients with diabetes remain at higher risk, and higher doses than previously recommended of intracoronary adenosine might have to be used in the evaluation of LMCA stenosis.

[Update on interventional cardiology]

Percutaneous intervention, whether coronary or noncoronary, continues to be a highly active area of medicine. This article contains an overview of the most notable developments reported in recent months. Drug-eluting stents (DESs) have provided one of the major advances in interventional cardiology as they have very effectively reduced the restenosis rate. Both randomized clinical trials and large observational studies have confirmed their safety, and their use has been extended to include highly complex conditions. Although thrombosis is one complication that can affect both conventional stents and DESs, the rate of late stent thrombosis is slightly, though significantly, higher with DESs. Primary angioplasty is the treatment of choice for patients with acute myocardial infarction if carried out under appropriate conditions, within a reasonable time period in a specialized center by experienced personnel. Use of thrombectomy devices can improve procedural outcomes and it appears that DES implantation is safe and effective, though more data are still needed. In patients with non-ST-elevation acute coronary syndrome, early treatment using an invasive approach coupled to the administration of various combinations of antiplatelet and antithrombotic drugs continues to be fundamental. Although left main coronary artery lesions are generally treated surgically, advances in percutaneous techniques and the use of DESs mean that an increasing number of patients are being treated using percutaneous coronary interventions. A number of studies have shown good results in other lesions and in high-risk patients with, for example, bifurcation lesions, chronic occlusions or diabetes. Intracoronary ultrasound is the predominant intracoronary diagnostic technique and it can be used to assist in optimizing DES implantation. In addition, measurement of the fractional flow reserve is helpful in evaluating the severity of moderate lesions whereas the high-resolution images provided by optical coherence tomography are particularly informative. Multislice computed tomography enables the presence of coronary artery disease to be ruled out and the technique is also useful as a complementary tool for interventional cardiologists. Research into regenerative techniques is promising but remains experimental at present. With regard to noncoronary interventions, new data have become available that support the use of a percutaneous approach in patients with patent foramen ovale. In addition, clinical experience with percutaneous aortic valve replacement, via either the transfemoral or transapical route, is increasing.