Long-term outcomes following fractional flow reserve-guided treatment of angiographically ambiguous left main coronary artery disease: A meta-analysis of prospective cohort studies

Diagnostic performance of intravascular ultrasound-based fractional flow reserve in evaluating of intermediate left main stenosis

BACKGROUND

The recently introduced ultrasonic flow ratio (UFR), is a novel fast computational method to derive fractional flow reserve (FFR) from intravascular ultrasound (IVUS) images. In the present study, we evaluate the diagnostic performance of UFR in patients with intermediate left main (LM) stenosis.

METHODS

This is a prospective, single center study enrolling consecutive patients with presence of intermediated LM lesions (diameter stenosis of 30%-80% by visual estimation) underwent IVUS and FFR measurement. An independent core laboratory assessed offline UFR and IVUS-derived minimal lumen area (MLA) in a blinded fashion.

RESULTS

Both UFR and FFR were successfully achieved in 41 LM patients (mean age, 62.0 ± 9.9 years, 46.3% diabetes). An acceptable correlation between UFR and FFR was identified (r = 0.688, P < 0.0001), with an absolute numerical difference of 0.03 (standard difference: 0.01). The area under the curve (AUC) in diagnosis of physiologically significant coronary stenosis for UFR was 0.94 (95% CI: 0.87-1.01), which was significantly higher than angiographic identified stenosis > 50% (AUC = 0.66, P < 0.001) and numerically higher than IVUS-derived MLA (AUC = 0.82; P = 0.09). Patient level diagnostic accuracy, sensitivity and specificity for UFR to identify FFR ≤ 0.80 was 82.9% (95% CI: 70.2-95.7), 93.1% (95% CI: 82.2-100.0), 58.3% (95% CI: 26.3-90.4), respectively.

CONCLUSION

In patients with intermediate LM diseases, UFR was proved to be associated with acceptable correlation and high accuracy with pressure wire-based FFR as standard reference. The present study supports the use of UFR for functional evaluation of intermediate LM stenosis.

Physiology-guided PCI versus CABG for left main coronary artery disease: insights from the DEFINE-LM registry

There have been no studies comparing clinical outcomes of physiology-guided revascularization in patients with unprotected left main coronary disease (ULMD) between percutaneous coronary intervention (PCI) vs. coronary artery bypass grafting (CABG). The aim of this study was to assess the long-term clinical outcomes between PCI and CABG of patients with physiologically significant ULMD. From an international multicenter registry of ULMD patients interrogated with instantaneous wave-free ratio (iFR), we analyzed data from 151 patients (85 PCI vs. 66 CABG) who underwent revascularization according to the cutoff value of iFR ≤ 0.89. Propensity score matching was employed to adjust for baseline clinical characteristics. The primary endpoint was a composite of all-cause death, non-fatal myocardial infarction, and ischemia-driven target lesion revascularization. The secondary endpoints were the individual components of the primary endpoint. Mean age was 66.6 (± 9.2) years, 79.2% male. Mean SYNTAX score was 22.6 (± 8.4) and median iFR was 0.83 (IQR 0.74-0.87). After performing propensity score matching analysis, 48 patients treated with CABG were matched to those who underwent PCI. At a median follow-up period of 2.8 years, the primary endpoint occurred in 8.3% in PCI group and 20.8% in CABG group, respectively (HR 3.80; 95% CI 1.04-13.9; p = 0.043). There was no difference in each component of the primary event (p > 0.05 for all). Within the present study, iFR-guided PCI was associated with lower cardiovascular events rate in patients with ULMD and intermediate SYNTAX score, as compared to CABG. State-of-the-art PCI vs. CABG for ULMD. Study design and primary endpoint in patients with physiologically significant ULMD. MACE was defined as the composite of all-cause death, non-fatal myocardial infarction, and target lesion revascularization. The blue line denotes the PCI arm, and the red line denotes the CABG arm. PCI was associated with significantly lower risk of MACE than CABG. CABG: coronary artery bypass grafting; iFR: instantaneous wave-free ratio; MACE: major adverse cardiovascular events; PCI: percutaneous coronary intervention; ULMD: unprotected left main coronary artery disease.

Contemporary Left Main Percutaneous Coronary Intervention: A State-of-the-art Review

The majority of the left ventricular myocardium is supplied by the left main coronary artery. Atherosclerotic obstruction of the left main coronary artery therefore leads to significant myocardial jeopardy. Coronary artery bypass surgery (CABG) has been the gold standard for left main coronary artery disease in the past. However, advancements in technology have established percutaneous coronary intervention (PCI) as a standard, safe and reasonable alternative to CABG, with comparable outcomes. Contemporary PCI of left main coronary artery disease comprises careful patient selection, accurate technique guided by either intravascular ultrasound or optical coherence tomography and - if necessary - physiological assessment using fractional flow reserve. This review focuses on current evidence from registries and randomised trials comparing PCI with CABG, procedural tips and tricks, adjuvant technologies and the triumph of PCI.

Instantaneous Wave-Free Ratio for the Assessment of Intermediate Left Main Coronary Artery Stenosis: Correlations With Fractional Flow Reserve/Intravascular Ultrasound and Prognostic Implications: The iLITRO-EPIC07 Study

BACKGROUND

There is little information available on agreement between fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) in left main coronary artery (LMCA) intermediate stenosis. Besides, several meta-analyses support the use of FFR to guide LMCA revascularization, but limited information is available on iFR in this setting. Our aims were to establish the concordance between FFR and iFR in intermediate LMCA lesions, to evaluate with intravascular ultrasound (IVUS) in cases of FFR/iFR discordance, and to prospectively validate the safety of deferring revascularization based on a hybrid decision-making strategy combining iFR and IVUS.

METHODS

Prospective, observational, multicenter registry with 300 consecutive patients with intermediate LMCA stenosis who underwent FFR and iFR and, in case of discordance, IVUS and minimal lumen area measurements. Primary clinical end point was a composite of cardiovascular death, LMCA lesion-related nonfatal myocardial infarction, or unplanned LMCA revascularization.

RESULTS

FFR and iFR had an agreement of 80% (both positive in 67 and both negative in 167 patients); in case of disagreement (31 FFR+/iFR- and 29 FFR-/iFR+) minimal lumen area was ≥6 mm² in 8.7% of patients with FFR+ and 14.6% with iFR+. Among the 300 patients, 105 (35%) underwent revascularization and 181 (60%) were deferred according to iFR and IVUS. At a median follow-up of 20 months, major adverse cardiac events incidence was 8.3% in the defer group and 13.3% in the revascularization group (hazard ratio, 0.71 [95% CI 0.30-1.72]; P=0.45).

CONCLUSIONS

In patients with intermediate LMCA stenosis, a physiology-guided treatment decision is feasible either with FFR or iFR with moderate concordance between both indices. In case of disagreement, the use of IVUS may be useful to indicate revascularization. Deferral of revascularization based on iFR appears to be safe in terms of major adverse cardiac events.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03767621.

Coronary CT angiography derived FFR in patients with left main disease

The presence of left main coronary artery disease (LMCAD) is associated with an unfavorable clinical outcome. The clinical utility of FFR_CT testing for non-invasive physiological assessment in LMCAD remains largely unknown. In this single center observational study LMCAD patients were retrospectively identified between November 2015 and December 2017. We evaluated the relationship between LMCAD diameter stenosis and downstream FFR_CT values, and the clinical consequences following FFR_CT testing in patients with LMCAD. The composite endpoint (all-cause death, myocardial infarction, unplanned revascularization) was determined over a median follow-up of 1.1 years. LMCAD was registered in 432 of 3202 (13%) patients having coronary CTA. FFR_CT was prescribed in 213 (49%), while 59 (14%) patients were referred directly to invasive angiography or myocardial perfusion imaging. FFR_CT was performed in 195 (45%) patients. LM stenosis severity was inversely related to downstream FFR_CT values. In patients with simple LMCAD with stenosis ≥ 50%, > 80% had FFR_CT > 0.80 in non-diseased proximal and downstream segments (n = 7). No patients with simple LMCAD and FFR_CT > 0.80 (n = 20) suffered an adverse clinical outcome. FFR_CT testing in patients with LMCAD is feasible. LM stenosis severity is inversely related to FFR_CT value. Patients with LMCAD and FFR_CT > 0.80 have favorable clinical outcomes at short-term follow-up. Large-scale studies assessing the clinical utility and safety of deferring invasive catheterization following FFR_CT testing in patients with LMCAD are warranted.

Physiology-Based Revascularization of Left Main Coronary Artery Disease

It is of critical importance to correctly assess the significance of a left main lesion. Underestimation of significance beholds the risk of inappropriate deferral of revascularization, whereas overestimation may trigger major but unnecessary interventions. This article addresses the invasive physiological assessment of left main disease and its role in deciding upon revascularization. It mainly focuses on the available evidence for fractional flow reserve and instantaneous wave-free ratio, their interpretation, and limitations. We also discuss alternative invasive physiological indices and imaging, as well as the link between physiology, ischemia, and prognosis.

How to select patients requiring coronary revascularisation using coronary physiology

The coronary angiogram is an indicator of flow limiting coronary artery disease but coronary physiology at the time of angiography is vital in assessing the true functional significance of coronary artery disease. With advances in guidewire technology and the greater use of physiology within the catheter laboratory, there is now a slow evolution of physiological indices in being able to reliably assess the functional significance of individual lesions and also the adequacy of revascularization in a growing range of clinical scenarios. As co-registration of physiology with the angiogram and intravascular imaging will become easier, we will find ourselves increasingly in an era of 'Precision PCI'.

Long-Term Clinical Outcomes of Unprotected Left Main Percutaneous Coronary Intervention: A Large Single-Centre Experience

Aims

This study sought to report the 10-year clinical outcomes of patients who underwent unprotected left main (LM) percutaneous coronary intervention (PCI) in a large centre.

Methods and Results

A total of 913 consecutive patients who underwent unprotected LM PCI from January 2004 to December 2008 at Fu Wai Hospital were retrospectively analysed; the mean age was 60.0 ± 10.9 years, females accounted for 22% of patients, diabetes was present in 27.7% of patients, and an LM bifurcation lesion occurred in 82.9% of patients. During the median follow-up of 9.7 years, major adverse cardiac or cerebrovascular events (MACCEs) occurred in 25.6% (234) of patients, and the rates of all-cause death, myocardial infarction, and stroke were 14.9%, 11.0%, and 7.1%, respectively. Cardiac death occurred in only 7.9% of patients. The estimated event rate was 41.9% for death/myocardial infarction/any revascularization and 45.9% for death/MI/stroke/any revascularization. Definite/probable stent thrombosis occurred in 4.3% (39) of patients. According to the subgroup analysis, IVUS-guided PCI was associated with less long-term MACCEs. Further multivariate analysis identified that age and LVEF<40% were the only independent predictors for 10-year death. Age, LVEF<40%, creatinine clearance, and incomplete revascularization were independent predictors for death/MI, while a two-stent strategy, diabetes, a transradial approach, and the use of bare metal stents (BMSs) or first-generation drug-eluting stents (DESs) were not.

Conclusions

Unprotected LM PCI in a large cohort of consecutive patients in a single large centre demonstrated favourable long-term outcomes up to 10 years even with the use of BMSs and first-generation of DESs.

Non-hyperaemic pressure ratios to guide percutaneous coronary intervention

The use of fractional flow reserve (FFR) in guiding revascularisation improves patient outcomes and has been well-established in clinical guidelines. Despite this, the uptake of FFR has been limited, likely attributable to the perceived increase in procedural time and use of hyperaemic agents that can cause patient discomfort. This has led to the development of instantaneous wave-free ratio (iFR), an alternative non-hyperaemic pressure ratio (NHPR). Since its inception, the use of iFR has been supported by an increasing body of evidence and is now guideline recommended. More recently, other commercially available NHPRs including diastolic hyperaemia-free ratio and resting full-cycle ratio have emerged. Studies have demonstrated that these indices, in addition to mean distal coronary artery pressure to mean aortic pressure ratio, are mathematically analogous (with specific nuances) to iFR. Additionally, there is increasing data demonstrating the equivalent diagnostic performance of alternative NHPRs in comparison with iFR and FFR. These NHPRs are now integral within most current pressure wire systems and are commonly available in the catheter laboratory. It is therefore key to understand the fundamental differences and evidence for NHPRs to guide appropriate clinical decision-making.

Impact of unprotected left main percutaneous coronary intervention on long-term clinical outcomes: a large single-center study

BACKGROUND

With the advancements of percutaneous coronary interventions (PCI), it is not clear whether unprotected left main (ULM) coronary artery disease (CAD) remains an independent predictor of adverse outcomes after PCI therapy. We have therefore carried out a large cohort study to investigate the impact of ULM disease on 2-year clinical outcomes in Chinese patients undergoing contemporary PCI treatment.

METHODS AND RESULTS

From January 2013 to December 2013, 10 724 consecutive patients undergoing PCI were prospectively collected. Two-year clinical outcomes were compared for patients undergoing ULM PCI and non-ULM PCI. Among the 10 724 patients, 272 (2.5%) patients underwent ULM PCI. Overall, these patients had higher baseline clinical risks of CAD and more extensive CAD compared with non-ULM PCI patients. During the 2-year follow-up, patients who underwent ULM PCI experienced higher incidence of cardiac death (2.2 vs. 0.7%; log-rank P=0.002), myocardial infarction (7.0 vs. 1.9%; log-rank P<0.001), stroke (2.9 vs. 1.3%; log-rank P=0.02), and definite and probable stent thrombosis (3.3 vs. 0.5%; log-rank P<0.001), than patients who underwent non-ULM PCI. However, the rates of revascularization (7.4 vs. 8.7%; log-rank P=0.48), target vessel revascularization (5.5 vs. 5.0%; log-rank P=0.66), and major adverse cardiac and cerebrovascular events (15.1 vs. 12.0%; log-rank P=0.11) were not significantly different between the groups. When performing adjusted Cox regression after propensity score matching, ULM PCI was not an independent risk factor of any clinical events (all P>0.05).

CONCLUSION

In this large cohort of patients who underwent modern PCI, ULM PCI patients had higher baseline clinical risks and poorer prognosis during 2-year follow-up. However, after multivariate analysis, ULM PCI was not an independent risk factor of any clinical adverse events.

Physiological Assessment of Coronary Lesions in 2020

PURPOSE OF REVIEW

Physiological assessment of coronary artery disease (CAD) is an essential component of the interventional cardiology toolbox. However, despite long-term data demonstrating improved outcomes, physiology-guided percutaneous coronary intervention (PCI) remains underutilized in current practice. This review outlines the indications and technical aspects involved in evaluating coronary stenosis physiology, focusing on the latest developments in the field.

RECENT FINDINGS

Beyond fractional flow reserve (FFR), non-hyperemic pressure ratios (NHPR) that assess coronary physiology at rest without hyperemia now abound. Additional advances in other alternative FFR approaches, including non-invasive coronary CT (FFR_CT), invasive angiography (FFR_angio), and optical coherence tomography (FFR_OCT), are being realized. Artificial intelligence algorithms and robust tools that enable detailed pre-procedure "virtual" intervention are also emerging. The benefits of coronary physiological assessment to determine lesion functional significance are well established. In addition to stable CAD, coronary physiology can be especially helpful in clinical scenarios such as left main and multivessel CAD, serial lesions, non-infarct-related arteries in acute coronary syndromes, and residual ischemia post-PCI. Today, coronary physiological assessment remains an indispensable tool in the catheterization laboratory, with an exciting technological future that will further refine clinical practice and improve patient care.

Two-Year Outcomes After Deferral of Revascularization Based on Fractional Flow Reserve

Background:

The safety of fractional flow reserve (FFR)-based deferral of revascularization remains to be fully established in real-world practice. We sought to assess clinical outcomes after deferral of revascularization based on FFR.

Methods:

The J-CONFIRM registry (Long-Term Outcomes of Japanese Patients With Deferral of Coronary Intervention Based on Fractional Flow Reserve in Multicenter Registry) prospectively enrolled 1263 patients with 1447 lesions in whom revascularization was deferred based on FFR at 28 Japanese centers. The primary study end point was the cumulative 2-year incidence of target vessel failure, including cardiac death, target-vessel related myocardial infarction, and clinically driven target vessel revascularization.

Results:

The mean FFR was 0.86±0.06. At 2 years, the target vessel failure rate was 5.5% in deferred lesions, mainly driven by a high rate of clinically driven target vessel revascularization (5.2%), and significantly increased with decreasing FFR, especially in the proximal location. Cardiac death and target-vessel related myocardial infarction rarely occurred during the 2-year follow-up (0.41% and 0.41%, respectively). Independent predictors of 2-year target vessel failure were FFR value (per 0.01 decrease; hazard ratio [HR] 1.07 [95% CI, 1.04–1.11], P <0.001), left main coronary artery lesion (HR, 5.89 [95% CI, 2.72–12.8], P <0.001), moderately to severely calcified lesion (HR, 2.49 [95% CI, 1.36–4.58]; P =0.003), hemodialysis (HR, 2.90 [95% CI, 1.11–7.58]; P =0.03), and right coronary artery lesion (HR, 1.78 [95% CI, 1.02–3.11], P =0.042).

Conclusions:

The J-CONFIRM registry demonstrated the 2-year target vessel failure rate was 5.5% in deferred lesions, highlighting the safety of FFR-based deferral of revascularization in daily practice.

Clinical Trial Registration:

URL: http://www.umin.ac.jp . Unique identifier: UMIN000014473.

Left main coronary artery disease: pathophysiology, diagnosis, and treatment

The advent of coronary angiography in the 1960s allowed for the risk stratification of patients with stable angina. Patients with unprotected left main coronary artery disease have an increased risk of death related to the large amount of myocardium supplied by this vessel. Although coronary angiography remains the preferred imaging modality for the evaluation of left main coronary artery stenosis, this technique has important limitations. Angiograms of the left main coronary artery segment can be difficult to interpret, and almost one-third of patients can be misclassified when fractional flow reserve is used as the reference. In patients with clinically significant unprotected left main coronary artery disease, surgical revascularization was shown to improve survival compared with medical therapy and has been regarded as the treatment of choice for unprotected left main coronary artery disease. Two large-scale clinical trials published in 2016 support the usefulness of catheter-based revascularization in selected patients with unprotected left main coronary artery disease. In this Review, we describe the pathophysiology of unprotected left main coronary artery disease, discuss diagnostic approaches in light of new noninvasive and invasive imaging techniques, and detail risk stratification models to aid the Heart Team in the decision-making process for determining the best revascularization strategy for these patients.

Validation of a novel non-hyperaemic index of coronary artery stenosis severity: the Resting Full-cycle Ratio (VALIDATE RFR) study

AIMS

Randomised controlled trials have reported instantaneous wave-free ratio (iFR) to be non-inferior to fractional flow reserve (FFR) for major adverse cardiovascular events at one year; however, iFR is limited by sensitive landmarking of the pressure waveform, and the assumption that maximal flow and minimal resistance occur during a fixed period of diastole. We sought to validate the resting full-cycle ratio (RFR), a novel non-hyperaemic index of coronary stenosis severity based on unbiased identification of the lowest distal coronary pressure to aortic pressure ratio (Pd/Pa), independent of the ECG, landmark identification, and timing within the cardiac cycle.

METHODS AND RESULTS

VALIDATE-RFR was a retrospective study designed to derive and validate the RFR. The primary endpoint was the agreement between RFR and iFR. RFR was retrospectively determined in 651 waveforms in which iFR was measured using a proprietary Philips/Volcano wire. RFR was highly correlated to iFR (R2=0.99, p<0.001), with a mean bias of -0.002 (95% limits of agreement -0.023 to 0.020). The diagnostic performance of RFR versus iFR was diagnostic accuracy 97.4%, sensitivity 98.2%, specificity 96.9%, positive predictive value 94.5%, negative predictive value 99.0%, area under the receiver operating characteristic curve of 0.996, and diagnostically equivalent within 1% (mean difference -0.002; 95% CI: -0.009 to 0.006, p=0.03). The RFR was detected outside diastole in 12.2% (341/2,790) of all cardiac cycles and 32.4% (167/516) of cardiac cycles in the right coronary artery where the sensitivity of iFR compared to FFR was lowest (40.6%).

CONCLUSIONS

RFR is diagnostically equivalent to iFR but unbiased in its ability to detect the lowest Pd/Pa during the full cardiac cycle, potentially unmasking physiologically significant coronary stenoses that would be missed by assessment dedicated to specific segments of the cardiac cycle.

Fractional flow reserve guided percutaneous coronary intervention optimization directed by high-definition intravascular ultrasound versus standard of care: Rationale and study design of the prospective randomized FFR-REACT trial

BACKGROUND

Post percutaneous coronary intervention (PCI) fractional flow reserve (FFR) is a significant predictor of major adverse cardiac events (MACE). The rationale for low post procedural FFR values often remains elusive based on angiographic findings alone, warranting further assessment using an FFR pullback or additional intravascular imaging. It is currently unknown if additional interventions intended to improve the PCI, decrease MACE rates.

STUDY DESIGN

The FFR REACT trial is a prospective, single-center randomized controlled trial in which 290 patients with a post PCI FFR <0.90 will be randomized (1:1) to either standard of care (no additional intervention) or intravascular ultrasound (IVUS)-directed optimization of the FFR (treatment arm). Eligible patients are those treated with angiographically successful PCI for (un)stable angina or non-ST elevation myocardial infarction (MI). Assuming 45% of patients will have a post PCI FFR <0.90, approximately 640 patients undergoing PCI will need to be enrolled. Patients with a post PCI FFR ≥ 0.90 will be enrolled in a prospective registry. The primary end point is defined as a composite of cardiac death, target vessel MI and clinically driven target vessel revascularisation (target vessel failure) at 1 year. Secondary end points will consist of individual components of the primary end point, procedural success, stent thrombosis and correlations on clinical outcome, changes in post PCI Pd/Pa and FFR and IVUS derived dimensions. All patients will be followed for 3 years.

CONCLUSION

The FFR-REACT trial is designed to explore the potential benefit of HD-IVUS-guided PCI optimization in patients with a post PCI FFR <0.90 (Dutch trial register: NTR6711).

A Practical Guide for Fractional Flow Reserve Guided Revascularisation

The presence and extent of myocardial ischaemia is a major determinant of prognosis and benefit from revascularisation in patients with stable coronary artery disease. Fractional Flow Reserve (FFR) is accepted as the reference standard for invasive assessment of ischaemia. Its ability to detect lesion specific ischaemia makes it a useful test in a wide range of patient and lesion subsets, with FFR guided intervention improving clinical outcomes and reducing health care costs compared to assessment with coronary angiography alone. This article will review the basic principles in FFR, practical tips in FFR guided revascularisation and the role of emerging non-hyperaemic indices of ischaemia.

Fractional flow reserve and resting indices for coronary physiologic assessment: Practical guide, tips, and tricks

Physiologic assessment using fractional flow reserve (FFR) to guide percutaneous coronary interventions (PCI) has been demonstrated to improve clinical outcomes, compared to angiography-guided PCI. Recently, resting indices such as resting Pd/Pa, "instantaneous wave-free ratio", and contrast medium induced FFR have been evaluated for the assessment of the functional consequences of coronary lesions. Herein, we review and discuss the use of FFR and other indices for the functional assessment of coronary lesions. This review will cover theoretical aspects, as well as practical points and common pitfalls related to coronary physiological assessment. © 2017 Wiley Periodicals, Inc.

Physiological assessment of left main coronary artery disease

The left main coronary artery (LMCA) is responsible for supplying the majority of the left ventricular myocardium. Visual estimation of stenosis severity on angiography has major limitations and methods to assess functional significance, such as fractional flow reserve (FFR), have been shown to yield better outcomes; however, to date, major trials examining the use of such physiological indices have excluded LMCA disease. Furthermore, LMCA disease commonly co-exists with downstream disease, which complicates the interpretation of coronary physiological data. This review summarises existing evidence for physio-‌logy-guided management of LMCA disease. It will also explore the difficulties posed when functionally assessing LMCA lesions and outline potential solutions. Finally, we aim to provide insight into how novel physiological tools may improve the management of LMCA disease in the future.

Assessing the left main stem in the cardiac catheterization laboratory. What is "significant"? Function, imaging or both?

Revascularization of significant Left Main Stem (LMS) disease improves clinical outcomes. This can be achieved through either Coronary Artery Bypass Grafting or Percutaneous coronary intervention. Defining a significant stenosis of the LMS can be challenging and debatable, as most data have been derived using angiographic assessment alone, with a threshold of 50% luminal stenosis used as a marker of functional significance. The use of adjunctive technologies like Intravascular Ultrasound and Fractional Flow Reserve has improved our ability to accurately assess the anatomical severity and physiological significance of coronary artery stenoses, much more so, than can be achieved through conventional angiography alone. An improved assessment of LMS disease through these adjunctive techniques offers procedural and clinical benefits. Rather than focus on the preferred methods of revascularisation, this article aims to highlight the common pitfalls and misconceptions in the assessment of LMS stenoses. We also propose a simple algorithm for the assessment of LMS disease to help guide revascularisation decisions.

Fractional flow reserve: a clinical perspective

Fractional flow reserve (FFR) is a reference invasive diagnostic test to assess the physiological significance of an epicardial coronary artery stenosis. FFR-guided percutaneous coronary intervention in stable coronary artery disease has been assessed in three seminal clinical trials and the indications for FFR assessment are expanding into other clinical scenarios. In this article we review the theoretical, experimental and clinical basis for FFR measurement. We place FFR measurement in the context of the comprehensive invasive assessment of coronary physiology in patients presenting with known or suspected angina pectoris in daily clinical practice, and review the recent developments in FFR assessment.

Performing and Interpreting Fractional Flow Reserve Measurements in Clinical Practice: An Expert Consensus Document

Fractional flow reserve (FFR) measurements can determine the haemodynamic relevance of coronary artery stenoses. Current guidelines recommend their use in lesions in the absence of non-invasive proof of ischaemia. The prognostic impact of FFR has been evaluated in randomised trials, and it has been shown that revascularisation can be safely deferred if FFR is >0.80, while revascularisation of stenoses with FFR values ≤0.80 results in significantly lower event rates compared to medical treatment. Left main stenoses, aorto-ostial lesions, as well as patients with left ventricular hypertrophy and severely-impaired ejection fraction, have been excluded from large, randomised trials. While FFR measurements are relatively straightforward to perform, uncertainty about procedural logistics, as well as data acquisition and interpretation in specific situations, could explain why they are not widely used in clinical practice. We summarise the clinical data in support of FFR measurements, and provide recommendations for performing and interpreting the procedure.

Comparing the adverse clinical outcomes associated with fraction flow reserve-guided versus angiography-guided percutaneous coronary intervention: a systematic review and meta-analysis of randomized controlled trials

Background

Recently published randomized controlled trials have shown different results compared to the Fraction Flow Reserve Versus Angiography for Multi-vessel Evaluation (FAME) study. Therefore, this current analysis aimed to compare the adverse clinical outcomes associated with Fraction Flow Reserve (FFR)-guided versus standard angiography-guided Percutaneous Coronary Intervention (PCI) using a large number of randomized patients.

Methods

PubMed/Medline, EMBASE and the Cochrane library were searched for studies comparing FFR-guided with angiography-guided PCI. Mortality, Myocardial Infarction (MI), repeated revascularization and Major Adverse Cardiac Events (MACEs) at any follow up period following PCI were considered as the clinical endpoints in this analysis. Odds Ratios (OR) with 95% Confidence Intervals (CIs) were calculated and the analyses were carried out by the RevMan 5.3 software. Ethical approval was not necessary for this type of study.

Results

A total number of 2138 patients (1080 patients with FFR-guided versus 1058 patients with angiography-guided PCI) were included. Results of this analysis showed mortality not to be significantly different between FFR-guided and angiography-guided PCI with OR: 0.70, 95% CI: 0.39 – 1.25; P = 0.22, I² = 0%. Total repeated revascularization and Target Lesion Revascularization were also similarly manifested with OR: 0.82, 95% CI: 0.60 – 1.13; P = 0.22, I² = 0% and OR: 0.88, 95% CI: 0.43 – 1.80; P = 0.73, I² = 0% respectively. In addition, MACEs were also not significantly lower in the FFR-guided PCI group with OR: 0.82, 95% CI: 0.64 – 1.06; P = 0.13, I² = 0%. However, FFR-guided PCI was associated with a significantly lower rate of re-infarction with OR: 0.67, 95% CI: 0.47 – 0.96; P = 0.03, I² = 0%.

Conclusion

FFR-guided PCI was not associated with significantly higher adverse clinical outcomes when compared to angiography-guided PCI. A significantly lower rate of re-infarction associated with FFR-guided PCI could show an important benefit. However, due to the limited number of patients analyzed, this hypothesis should further be confirmed in future trials.

[Fractional flow reserve and instantaneous wave-free ratio for the physiological assessment of coronary artery stenosis in the catheterization laboratory: Practical tips]

In recent years, a large body of evidence has revealed the limitations of angiographic evaluation in determining the physiological significance of coronary stenosis, particularly when these are intermediate lesions. Percutaneous coronary interventions (PCI) guided by physiological assessment using fractional flow reserve (FFR) have been shown to reduce cardiovascular events when compared to angiography alone. Recently, another coronary physiologic parameter has been introduced: the "instantaneous wave-free ratio" (iFR). In this review, we will discuss the FFR, the iFR, and their use in the functional assessment of coronary stenosis in the cardiac catheterization laboratory. This review will cover theoretical aspects for non-interventional cardiologists, as well as practice points and common pitfalls related to coronary physiological assessment for interventional cardiologists.

Update on percutaneous intervention for left main coronary artery stenosis

Percutaneous coronary intervention (PCI) using drug-eluting stents (DES) is currently considered as a viable alternative to coronary artery bypass graft surgery (CABG) for selected patients with left main coronary artery disease. The updated results of the landmark randomized trials comparing CABG versus PCI demonstrated comparable 5-year outcomes and are in line with the current guidelines that designate PCI as a reasonable treatment in this disease subset. Given that the completed randomized trials did not include contemporary DESs, the upcoming results of the ongoing trials evaluating the performance of new-generation DES compared with CABG (such as the EXCEL trial), may further help to clarify the current role and future recommendations of PCI for left main coronary artery disease. Apart from the recent stent technology, further improvements in outcomes after PCI may be possible when it is used with an integrated approach that combines functional concepts for decision-making, adjunctive imaging support and optimal pharmacotherapies.

Is the left main just another artery to FFR?

This meta-analysis includes all prospective FFR studies of the left main artery with outcomes. Patients who had deferral of revascularization in FFR-negative stenoses had no difference in cardiovascular events compared with patients who underwent revascularization. FFR-guided revascularization of left main stenosis is safe and effective.