Hemodynamic evaluation of coronary artery bypass graft lesions using fractional flow reserve

Functional Assessment of Coronary Artery Lesions-Old and New Kids on the Block

Angiography is inaccurate in assessing functional significance of coronary lesions, and often stenoses deemed severe on angiographic assessment do not restrict coronary blood flow at rest or with maximal dilatation. Angiography-guided revascularization has not shown improvement in hard clinical outcomes in stable ischemic heart disease (SIHD). Most current guidelines for SIHD recommend invasive functional assessment of lesions to guide revascularization if prior evidence of ischemia is not available. There has been several recent advances and development of novel methods in this arena. Various contemporary clinical trials have been undertaken for validation of these indices. Here we review the physiological basis, tools, techniques, and evidence base for various invasive (resting as well as hyperemic) and noninvasive methods for functional assessment of coronary lesions. Left main stenosis, bifurcation lesions, serial stenosis, and acute coronary syndrome each causes unique disequilibrium that may affect measurements and require special considerations for accurate functional assessment.

Long-term outcomes after fractional flow reserve-guided percutaneous coronary intervention in patients with severe coronary stenosis

Objective

To explore the safety and efficacy of FFR-guided percutaneous coronary intervention (PCI) in vessels with severe diameter stenosis.

Methods & Results

Of 1090 patients undergoing fractional flow reserve (FFR) assessment from 2002 to 2009, we identified 167 patients in whom FFR was measured in at least one 70%–89% stenotic lesion. These patients were subdivided into an FFR-defer group (n = 49) if PCI was deferred (FFR > 0.80), and an FFR-perform group (n = 118) if PCI was performed (FFR ≤ 0.80). Comparatively, an additional 1176 patients undergoing PCI in at least one lesion with 70%–89% stenosis but without measurement of FFR served as a control (angiography-guided) group. Clinical outcomes were compared during a median follow-up of 49.0 months. The 5-year Kaplan-Meier estimated revascularization rates were 16% in the FFR-defer group and 33% in the FFR-perform group (P = 0.046). The incidence of major adverse cardiac events were comparable in these two groups (HR = 0.82, 95% CI: 0.37–1.82, P = 0.63). The number of stents placed was significantly lower in the FFR-guided group (0.9 ± 0.8 vs. 1.4 ± 0.8, P < 0.001).

Conclusions

Functional revascularization for lesions with visually severe stenosis is clinically safe and associated with fewer stents use. This study suggests that extending the use of FFR to more severe coronary lesions may be reasonable.

Outcomes of Fractional Flow Reserve-Based Deferral in Saphenous Vein Graft Narrowing

Fractional flow reserve (FFR) has been shown to improve clinical decision-making for revascularization in intermediate coronary stenosis in native coronary arteries of patients with stable coronary disease. However, its use for saphenous vein graft (SVG) lesions has not been well validated. We sought to determine the prognostic value of deferring intervention in lesions with FFR >0.8 in SVG lesions. Clinical, angiographic, and hemodynamic variables and long-term outcomes were recorded in consecutive patients in whom percutaneous coronary intervention was deferred based on an FFR >0.8 for intermediate native coronary artery or SVG stenosis. Thirty-three patients underwent FFR of SVG lesions and were compared with 532 patients who underwent native vessel FFR during the same period. There were no differences in age (66.6 [interquartile range, IQR 63 to 76] vs 65 years [IQR 61 to 70]; p = 0.12), diabetes (41% vs 50%; p = 0.35), or hypertension (94% vs 97%; p = 0.71). During a median follow-up of 3.2 years (IQR 1.7 to 4.6 years) major adverse cardiac event was significantly higher in SVG group (36% vs 21%; log rank p = 0.01). Similarly, the rate of target vessel failure was significantly higher in the SVG group (27% vs 14%; p = 0.01). Deferred SVG lesions had the worst survival free of target vessel failure compared with deferred native lesions in both patients with and without previous CABG. An SVG lesion was an independent predictor of major adverse cardiac events on Cox proportional hazards analysis (hazard ratio 2.26; confidence interval 1.19, 4.28; p = 0.01). In conclusion, nonischemic FFR carries a significantly worse prognosis in SVG compared with non-SVG lesions. Caution is warranted in utilizing FFR for clinical decision-making in SVG lesions.

Fractional flow reserve (FFR) as a guide to treat coronary artery disease

INTRODUCTION

The presence and extent of myocardial ischemia are the major determinants of prognosis in patients with coronary artery disease (CAD). Unlike coronary angiography alone, fractional flow reserve (FFR) has enabled interventional cardiologists to accurately determine whether coronary atherosclerotic plaques are responsible for myocardial ischemia, and therefore deserve to be revascularized. Areas covered: An overview on the role of FFR in the diagnosis and treatment of coronary artery disease, as well as the potential related controversies is provided. Authors describe the coronary physiology underneath this technique and all the procedural aspects in the catheterization laboratory. The landmark trials and the current applications in different coronary lesions and syndromes are also described and potential future research involving FFR and comparisons with other methodologies for the evaluation of coronary physiology are introduced. Expert commentary: FFR is still unsurpassed in diagnostic performance when compared to non-hyperemic indices and noninvasive techniques, and remains the gold standard for the detection of ischemia-inducing coronary stenoses. FFR-guided PCI has been demonstrated superior to an angiography-guided PCI and over medical therapy alone, and ongoing investigation will clarify whether it could perform better, or at least equalize the results of cardiac surgery in patients with severe multivessel disease.

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.

ACC/AATS/AHA/ASE/ASNC/SCAI/SCCT/STS 2017 Appropriate Use Criteria for Coronary Revascularization in Patients With Stable Ischemic Heart Disease : A Report of the American College of Cardiology Appropriate Use Criteria Task Force, American Association for Thoracic Surgery, American Heart Association, American Society of Echocardiography, American Society of Nuclear Cardiology, Society for Cardiovascular Angiography and Interventions, Society of Cardiovascular Computed Tomography, and Society of Thoracic Surgeons

The American College of Cardiology, Society for Cardiovascular Angiography and Interventions, Society of Thoracic Surgeons, and American Association for Thoracic Surgery, along with key specialty and subspecialty societies, have completed a 2-part revision of the appropriate use criteria (AUC) for coronary revascularization. In prior coronary revascularization AUC documents, indications for revascularization in acute coronary syndromes and stable ischemic heart disease (SIHD) were combined into 1 document. To address the expanding clinical indications for coronary revascularization, and to align the subject matter with the most current American College of Cardiology/American Heart Association guidelines, the new AUC for coronary artery revascularization were separated into 2 documents addressing SIHD and acute coronary syndromes individually. This document presents the AUC for SIHD.Clinical scenarios were developed to mimic patient presentations encountered in everyday practice. These scenarios included information on symptom status; risk level as assessed by noninvasive testing; coronary disease burden; and, in some scenarios, fractional flow reserve testing, presence or absence of diabetes, and SYNTAX score. This update provides a reassessment of clinical scenarios that the writing group felt were affected by significant changes in the medical literature or gaps from prior criteria. The methodology used in this update is similar to the initial document but employs the recent modifications in the methods for developing AUC, most notably, alterations in the nomenclature for appropriate use categorization.A separate, independent rating panel scored the clinical scenarios on a scale of 1 to 9. Scores of 7 to 9 indicate that revascularization is considered appropriate for the clinical scenario presented. Scores of 1 to 3 indicate that revascularization is considered rarely appropriate for the clinical scenario, whereas scores in the mid-range of 4 to 6 indicate that coronary revascularization may be appropriate for the clinical scenario.As seen with the prior coronary revascularization AUC, revascularization in clinical scenarios with high symptom burden, high-risk features, and high coronary disease burden, as well as in patients receiving antianginal therapy, are deemed appropriate. Additionally, scenarios assessing the appropriateness of revascularization before kidney transplantation or transcatheter valve therapy are now rated. The primary objective of the AUC is to provide a framework for the assessment of practice patterns that will hopefully improve physician decision making.

Current State of the Art in Approaches to Saphenous Vein Graft Interventions

Saphenous vein grafts (SVGs), used during coronary artery bypass graft surgery for severe coronary artery disease, are prone to degeneration and occlusion, leading to poor long-term patency compared with arterial grafts. Interventions used to treat SVG disease are susceptible to high rates of periprocedural MI and no-reflow. To minimise complications seen with these interventions, proper stents, embolic protection devices (EPDs) and pharmacological selection are crucial. Regarding stent selection, evidence has demonstrated superiority of drug-eluting stents over bare-metal stents in SVG intervention. The ACCF/AHA/SCA American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions guidelines recommend the use of EPDs during SVG intervention to decrease the risk of periprocedural MI, distal embolisation and no-reflow. The optimal pharmacological treatment for slow or no-reflow remains unclear, but various vasodilators show promise.

Fractional flow reserve in 2017: current data and everyday practice

INTRODUCTION

Fractional flow reserve (FFR) is an objective physiological index utilized in coronary angiography. It expresses the blood flow in the presence of a coronary artery stenosis as a fraction of the normal blood flow and gives information regarding the functional significance of the lesion. FFR guided percutaneous coronary intervention (PCI) has been shown to be superior to angiography guided PCI in several trials and registries. In addition, it appears that the use of FFR may also be preferable from an economic perspective. Areas covered: This article will cover the physiological principles underpinning FFR, the landmark clinical trials that have established its diagnostic utility and the current recommendations for the use of the procedure in daily practice. We will also examine potential future directions for the technology and try to predict how its use will evolve in the next five years. Expert commentary: We see FFR as an essential diagnostic tool in the modern catheterization laboratory, enabling physicians to make optimal decisions regarding percutaneous coronary intervention for an individual patient. It must be stated however that FFR is an adjunctive invasive functional tool that must be used in conjunction with sensible clinical history and exam findings pertaining to the individual patient. We expect that the results of FAME3 will further establish the role of FFR in risk stratifying patients with 3 vessel disease by utilizing a functional SYNTAX score.

[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.

Saphenous Vein Graft Interventions

Saphenous vein graft interventions compose a small but important subset of percutaneous coronary revascularization. Because of their unique biology, percutaneous angioplasty and stenting require tailored patient and lesion selection and modification of intervention technique to optimize outcomes. The use of embolic protection and appropriate adjunctive pharmacology can help minimize periprocedural complications, such as the no-reflow phenomenon. Recommendations for best practice in saphenous vein graft interventions continue to evolve with emerging research and therapy.

Transient right internal thoracic arterial graft kink related to respiratory movements: documentation of its existence, relevance and proposed management

In this case report, we provide the first detailed description of an intermittent mechanical kink of a right internal thoracic artery (ITA) graft to the left anterior descending coronary artery secondary to respiratory movements, and its assessment by pressure wire derived fractional flow reserve (FFR). The patient presented with recurrent unstable angina and documented anterior/anterolateral ischemia. Persistent symptoms were attributed to the ITA kink and stenting was planned on clinical grounds. However, the lesion proved not physiologically significant when FFR was assessed after intermittency related to respiratory movements was documented. Complex stenting was therefore avoided and medical therapy was prescribed for distal diagonal disease. We therefore propose that intermittency should be actively investigated when a kink is documented in a coronary bypass graft by conventional angiography (using dedicated angiographic evaluation in maximal inspiration and expiration). Furthermore, when this type of lesion is encountered, we suggest that it should be assessed physiologically using pressure wire derived FFR before potentially complex interventions are considered.

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.

Long-term outcomes of fractional flow reserve-guided vs. angiography-guided percutaneous coronary intervention in contemporary practice

AIMS

Fractional flow reserve (FFR) is the reference standard for the assessment of the functional significance of coronary artery stenoses, but is underutilized in daily clinical practice. We aimed to study long-term outcomes of FFR-guided percutaneous coronary intervention (PCI) in the general clinical practice.

METHODS AND RESULTS

In this retrospective study, consecutive patients (n = 7358), referred for PCI at the Mayo Clinic between October 2002 and December 2009, were divided in two groups: those undergoing PCI without (PCI-only, n = 6268) or with FFR measurements (FFR-guided, n = 1090). The latter group was further classified as the FFR-Perform group (n = 369) if followed by PCI, and the FFR-Defer group (n = 721) if PCI was deferred. Clinical events were compared during a median follow-up of 50.9 months. The Kaplan-Meier fraction of major adverse cardiac events at 7 years was 57.0% in the PCI-only vs. 50.0% in the FFR-guided group (P = 0.016). Patients with FFR-guided interventions had a non-significantly lower rate of death or myocardial infarction compared with those with angiography-guided interventions [hazard ratio (HR): 0.85, 95% CI: 0.71-1.01, P = 0.06]; the FFR-guided deferred-PCI strategy was independently associated with reduced rate of myocardial infarction (HR: 0.46, 95% CI: 0.26-0.82, P = 0.008). After excluding patients with FFR of 0.75-0.80 and deferring PCI, the use of FFR was significantly associated with reduced rate of death or myocardial infarction (HR: 0.80, 95% CI: 0.66-0.96, P = 0.02).

CONCLUSION

In the contemporary practice, an FFR-guided treatment strategy is associated with a favourable long-term outcome. The current study supports the use of the FFR for decision-making in patients undergoing cardiac catheterization.

Coronary Artery Bypass Grafting With Y-Saphenous Vein Grafts

Introduction: The saphenous vein is one of the indispensible grafts for coronary revascularization despite the advantages of arterial grafts over veins. It can be used in different configurations with different anastomosis (eg, sequential, composite, or Y-graft) techniques. Our aim was to investigate early and midterm results of Y-type anastomosis of saphenous vein grafts for complete coronary revascularization. Material and methods: Coronary artery bypass grafting (CABG) with Y-graft technique was performed in 512 patients between February 1998 and June 2007. In total, 608 saphenous Y coronary anastomoses were performed. These anastomoses were on first and second obtuse marginal arteries (n: 323), first diagonal and first obtuse marginal arteries (n: 187), posterolateral and posterior descending artery (n: 79), and right coronary artery and posterior descending artery (n: 19). Endareterectomy was performed in 28 patients with severely calcified coronary arteries. Patients were evaluated for early and late survival, newly developing cardiac events, recurring angina, and reinterventions. Results: In the early postoperative period, new myocardial infarction (MI) occurred in 27 (5.2%) patients and mortality in 13 (2.5%). Follow-up included the results of 487 (98%) patients. Mean follow-up duration was 56 ± 24 months. Late mortality occurred in 36 (7.3%) patients, and in 13 (2.6%) patients new MI developed in the remote follow-up. Overall survival including all deaths at 3, 5, and 7 years was 94 ± 0.6%, 86 ± 1.3%, and 83 ± 2.1%, respectively, and actuarial freedom from angina recurrence at 3, 5, and 7 years was 95.2 ± 2.5%, 86.4 ± 3%, and 84.7 ± 4.6%, respectively. Among long-term survivors, 116 patients (25.7%), 49 being symptomatic, with 123 saphenous Y-type anastomoses having undergone angiography studies. Saphenous vein Y grafts were completely patent in 94 anastomoses (76.4%). Conclusions: Saphenous vein Y-type anastomosis technique can safely be used in patients with multivessel coronary artery disease (CAD) with successful long-term outcomes. As with sequential anastomosis, the safety of the technique may be attributed to the distribution of inflow from aorta into multiple vessels.