Thirty-month outcome after fractional flow reserve-guided versus conventional multivessel percutaneous coronary intervention

Illusion of revascularization: does anyone achieve optimal revascularization during percutaneous coronary intervention?

This Perspective article is a form of 'pastiche', inspired by the 1993 review by Lincoff and Topol entitled 'Illusion of reperfusion', and explores how their concept continues to apply to percutaneous revascularization in patients with coronary artery disease and ischaemia. Just as Lincoff and Topol argued that reperfusion of acute myocardial infarction was facing unresolved obstacles that hampered clinical success in 1993, we propose that challenging issues are similarly jeopardizing the potential benefits of stent-based angioplasty today. By analysing the appropriateness and efficacy of percutaneous coronary intervention (PCI), we emphasize the limitations of relying solely on visual angiographic guidance, which frequently leads to inappropriate stenting and overtreatment in up to one-third of patients and the associated increased risk of periprocedural myocardial infarction. The lack of optimal revascularization observed in half of patients undergoing PCI confers risks such as suboptimal physiology after PCI, residual angina and long-term stent-related events, leaving an estimated 76% of patients with an 'illusion of revascularization'. These outcomes highlight the need to refine our diagnostic tools by integrating physiological assessments with targeted intracoronary imaging and emerging strategies, such as co-registration systems and angiography-based computational methods enhanced by artificial intelligence, to achieve optimal revascularization outcomes.

Fractional flow reserve use in coronary artery revascularization: A systematic review and meta-analysis

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is recommended in revascularization guidelines for intermediate lesions. However, recent studies comparing FFR-guided PCI with non-physiology-guided revascularization have reported conflicting results. PubMed and Embase were searched for studies comparing FFR-guided PCI with non-physiology-guided revascularization strategies (angiography-guided, intracoronary imaging-guided, coronary artery bypass grafting). Data were pooled by meta-analysis using random-effects model. 26 studies enrolling 78,897 patients were included. FFR-guided PCI as compared to non-physiology-guided coronary revascularization had lower risk of all-cause mortality (odds ratio [OR] 0.79 95% confidence interval [CI] 0.64-0.99, I² = 53%) and myocardial infarction (MI) (OR 0.74 95% CI 0.59-0.93, I² = 44.7%). However, no differences between groups were found in terms of major adverse cardiac events (MACEs) (OR 0.86 95% CI 0.72-1.03, I² = 72.3%) and repeat revascularization (OR 1 95% CI 0.82-1.20, I² = 43.2%). Among patients with coronary artery disease (CAD), FFR-guided PCI as compared to non-physiology-guided revascularization was associated with a lower risk of all-cause mortality and MI.

Relationship between Whole Blood Viscosity and Lesion Severity in Coronary Artery Disease

Objective  This article investigates the relationship of fractional flow reserve (FFR) with whole blood viscosity (WBV) in patients who were diagnosed with chronic coronary syndrome and significant stenosis in the major coronary arteries and underwent the measurement of FFR. Material and Method  In the FFR measurements performed to evaluate the severity of coronary artery stenosis, 160 patients were included in the study and divided into two groups as follows: 80 with significant stenosis and 80 with nonsignificant stenosis. WBVs at low shear rate (LSR) and high shear rate (HSR) were compared between the patients in the significant and nonsignificant coronary artery stenosis groups. Results  In the group with FFR < 0.80 and significant coronary artery stenosis, WBV was significantly higher compared with the group with nonsignificant coronary artery stenosis in terms of both HSR (19.33 ± 0.84) and LSR (81.19 ± 14.20) ( p  < 0.001). In the multivariate logistic regression analysis, HSR and LSR were independent predictors of significant coronary artery stenosis (HSR: odds ratio: 1.67, 95% confidence interval: 1.17-2.64; LSR: odds ratio: 2.46, 95% confidence interval: 2.19-2.78). In the receiver operating characteristic (ROC) curve analysis, when the cutoff value of WBV at LSR was taken as 79.23, it had 58.42% sensitivity and 62.13% specificity for the prediction of significant coronary artery stenosis (area under the ROC curve: 0.628, p  < 0.001). Conclusion  WBV, an inexpensive biomarker that can be easily calculated prior to coronary angiography, was higher in patients with functionally severe coronary artery stenosis, and thus could be a useful marker in predicting the hemodynamic severity of coronary artery stenosis in patients with chronic coronary syndrome.

Does Moderate Coronary Stenosis Affect the Fate of the Left Internal Thoracic Artery Graft?

Introduction

In this study we try to observe the fate of the left internal thoracic artery grafts that were bypassed to left anterior descending artery with moderate stenosis identified with fractional flow reserve (FFR) technique. Doppler ultrasonography was chosen as a noninvasive screening method.

Methods

A total of 30 patients who underwent coronary artery bypass grafting depending on results of the fractional flow reserve between January 2007 and January 2012, were subjected to transthoracic color Doppler ultrasonographic evaluation irrespective of the presence of symptoms, and the presence of a systolic-diastolic flow pattern was investigated using the supraclavicular approach.

Results

The left internal thoracic artery graft was found to be functional in 63.3% of patients within a mean period of 35.1±19.7 months between coronary bypass and color Doppler ultrasonography. This period was found to be 29.4±19.6 months in the functional graft group, and 44.7±16.6 months in the dysfunctional graft group (P=0.046). Preoperative complaints of angina were reported to fall from 88.9% to 16.7% in the functional graft group, when compared to the postoperative period (P<0.001), but fell from 90.9% to 36.4% in the dysfunctional graft group (P=0.034).

Conclusion

Functional left internal thoracic artery graft rates of the study population were found to be lower than the studies reported in the literature.

Myocardial Mass Contributes to the Discrepancy Between Anatomic Stenosis Severity Assessed by Intravascular Ultrasound and Fractional Flow Reserve in Intermediate Lesions of the Coronary Artery

OBJECTIVES

The present study investigated the major contributors to the discrepancy between the minimal lumen area (MLA) and fractional flow reserve (FFR).

BACKGROUND

There was considerable discrepancy between MLA or diameter stenosis (DS) and FFR.

METHODS

We enrolled 744 patients with intermediate stenoses of the left anterior descending artery (LAD). Summed epicardial coronary artery length distal to the target stenosis was obtained from each longest view of the vessels on the coronary angiograms. Mismatching was defined as a lesion with FFR of >0.80 and MLA smaller than the best cut-off value (BCV) for predicting FFR of ≤0.80. Reverse mismatching was defined as a lesion with FFR of ≤0.80 and MLA larger than the BCV.

RESULTS

Summed epicardial coronary artery length was longer at the lesions of proximal LAD than that of middle LAD (380 mm ± 82 mm vs. 341 mm ± 80 mm, P < 0.001). Reverse mismatching was found more frequently in the proximal than middle LAD (28.3% vs. 5.5%, P < 0.001). Independent predictors of FFR ≤ 0.80 were age, male, multi-vessel disease, proximal LAD lesion, MLA, DS, plaque burden at distal reference, lesion length and summed epicardial coronary artery length. Proximal LAD lesion was an independent predictor of reverse mismatching (hazard ratio 3.162, 1.858-5.382, P < 0.001).

CONCLUSIONS

Myocardial mass subtended by a lesion is an important factor predicting FFR ≤0.80 and discrepancy between FFR and MLA. Myocardial mass subtended by a lesion should be considered when determining the revascularization therapy by intravascular ultrasound parameters. © 2017 Wiley Periodicals, Inc.

Transluminal Attenuation Gradient for the Noninvasive Assessment of Functional Significance in Coronary Artery Stenoses

Invasive and noninvasive methods currently used for imaging-based evaluation of the coronary tree reveal a high number of moderate degree coronary artery stenoses, and the decision to revascularize or not such lesions could be difficult in different clinical settings. Therefore, the need for evaluating the functional significance of such lesions appeared obvious and led to the introduction of fractional flow reserve methodology, a new tool proposed for the evaluation of the functional impact of a coronary stenosis. At the same time, new tools have been proposed for the same application, such as the transluminal attenuation gradient along a coronary artery stenosis, determined using cardiac computed angiography. The aim of this short update is to summarize the recent advances in the field of invasive and noninvasive evaluation of the functional significance of coronary artery stenoses.

Comparison of failure rates of crossing side branch with pressure vs. coronary guidewire: a meta-analysis

OBJECTIVES

The aim of this study was to compare the failure rates of crossing side branch (SB) with pressure guidewire vs. coronary guidewire after main vessel (MV) stenting in coronary bifurcation lesions (CBL).

BACKGROUND

Percutaneous coronary intervention of CBL is technically difficult. The European Bifurcation Club recommends performing either fractional flow reserve (FFR) estimation of the SB or final kissing balloon inflation (FKBI) after the MV stenting when a significant SB ostial stenosis is present. Even though FFR is recommended in CBL, there is concern about SB crossing with pressure guidewire among interventionists.

MATERIALS AND METHODS

We undertook a comprehensive literature search to identify all relevant studies reporting the failure rates of SB crossing after MV stenting with either pressure or coronary guidewire. A random effects model was used to compare the failure rates between the two approaches.

RESULTS

Our search identified six studies that reported failure rates of SB crossing with a pressure guidewire (n = 648) and 11 studies that reported failure rates of SB crossing with a coronary guide-wire (n = 2601). Estimated pooled failure rate was 3·9% (95% CI: 1·5% to 9·6%) for inability to cross SB with pressure guidewire. Estimated pooled failure rate of SB crossing with coronary guidewire was 3·1% (95% CI: 1·5% to 6·2%). There was no significant difference between the failure rates in the two groups (P = 0·70).

CONCLUSION

The failure rates of SB crossing after MV stenting are low with both pressure and coronary guidewire procedures, with no significant difference between the two approaches.

New Invasive Assessment Measures of Coronary Artery Disease Severity

Ischemic heart disease is the leading cause of mortality worldwide. The assessment and treatment of patients with ischemic heart disease have advanced greatly over the past decade. Particular attention has been given recently to the recognition of lesions that cause ischemia or that are prone to plaque rupture. New invasive measures of coronary artery disease have been developed, including fractional flow reserve, intravascular ultrasound, optical coherence tomography, and most recently, near-infrared spectroscopy. These technologies have helped to guide the assessment of hemodynamically significant lesions and have shown particular promise in guiding percutaneous coronary interventions. However, mortality and the rate of revascularization have shown mixed results to date. This review seeks to investigate the use and potential benefit of these technologies, with particular attention to clinical end points.

The Value of Pre- and Post-Stenting Fractional Flow Reserve for Predicting Mid-Term Stent Restenosis Following Percutaneous Coronary Intervention (PCI)

Measuring fractional flow reserve (FFR) in percutaneous coronary intervention (PCI) has predictive value for PCI outcome. We decided to examine the utility of pre- and post-stenting FFR as a predictor of 6-month stent restenosis as well as MACE (major adverse cardiac events). Pre- and post-stenting FFR values were measured for 60 PCI patients. Within 6 months after stenting, all patients were followed for assessment of cardiac MACE including myocardial infarction, unstable angina, or positive exercise test. Stent restenosis was also assessed. Cut-off values for pre- and post-stenting FFR measurements were considered respectively as 0.65 and 0.92. Stent restenosis was detected in 4 patients (6.6%). All 4 patients (100%) with restenosis had pre-stenting FFR of < 0.65, while only 26 of 56 patients without restenosis (46.4%) had pre-stenting FFR value of < 0.65 (P = 0.039). Mean pre-stenting FFR in patients with restenosis was significantly lower than in those without restenosis (0.25 ± 0.01 vs. 0.53 ± 0.03, P = 0.022). Although stent restenosis was higher in patients with post-stenting FFR of < 0.92 (2 cases, 9.5%) than in those with FFR value of ≥ 0.92 (2 cases, 5.1%), the difference was not statistically (P = 0.510). Pre-stenting FFR, the use of longer stents, and history of diabetes mellitus can predict stent restenosis, but the value of post-stenting FFR for predicting restenosis was not explicit.

Usefulness and safety of intracoronary administration of nicorandil for evaluating fractional flow reserve in Japanese patients

BACKGROUND

Fractional flow reserve (FFR) is useful for determining the functional significance of epicardial coronary stenosis and may facilitate clinical decision making in patients with an equivocal coronary stenosis for coronary revascularization. Therefore, determining an efficient and safe method to achieve hyperemia is important for evaluating FFR. We investigated the usefulness and safety of intracoronary bolus administration of nicorandil compared with intravenous administration of adenosine triphosphate (ATP) for evaluating FFR in Japanese patients with suspected angina pectoris.

METHODS

First, we evaluated the most appropriate hyperemic dose of nicorandil in the first 11 consecutive patients out of 101 Japanese patients. Next, we compared the FFR induced by ATP and by 2 mg of nicorandil in 130 vessels of the 101 patients.

RESULTS

FFR was measured according to nicorandil dose in 14 vessels among 11 of the 101 patients; 92.9% of the patients achieved hyperemia with 2 mg of nicorandil. The FFR values obtained with ATP were significantly correlated with those obtained with 2 mg of nicorandil (regression coefficient = 0.974, R(2) = 0.933, P < 0.001). There were no hypotension cases needing a vasopressor after ATP or nicorandil administration, and there was 1 case of transient second-degree atrioventricular block after ATP administration. The time taken to achieve hyperemia after nicorandil administration (18.9 ± 9.6 seconds) was significantly shorter than that after ATP administration (197.9 ± 23.8 seconds) (P < 0.001).

CONCLUSIONS

Intracoronary nicorandil administration is more useful than and as safe as intravenous administration of ATP for evaluating FFR in Japanese patients.

Prognostic value of fractional flow reserve: linking physiologic severity to clinical outcomes

BACKGROUND

Fractional flow reserve (FFR) has become an established tool for guiding treatment, but its graded relationship to clinical outcomes as modulated by medical therapy versus revascularization remains unclear.

OBJECTIVES

The study hypothesized that FFR displays a continuous relationship between its numeric value and prognosis, such that lower FFR values confer a higher risk and therefore receive larger absolute benefits from revascularization.

METHODS

Meta-analysis of study- and patient-level data investigated prognosis after FFR measurement. An interaction term between FFR and revascularization status allowed for an outcomes-based threshold.

RESULTS

A total of 9,173 (study-level) and 6,961 (patient-level) lesions were included with a median follow-up of 16 and 14 months, respectively. Clinical events increased as FFR decreased, and revascularization showed larger net benefit for lower baseline FFR values. Outcomes-derived FFR thresholds generally occurred around the range 0.75 to 0.80, although limited due to confounding by indication. FFR measured immediately after stenting also showed an inverse relationship with prognosis (hazard ratio: 0.86, 95% confidence interval: 0.80 to 0.93; p < 0.001). An FFR-assisted strategy led to revascularization roughly half as often as an anatomy-based strategy, but with 20% fewer adverse events and 10% better angina relief.

CONCLUSIONS

FFR demonstrates a continuous and independent relationship with subsequent outcomes, modulated by medical therapy versus revascularization. Lesions with lower FFR values receive larger absolute benefits from revascularization. Measurement of FFR immediately after stenting also shows an inverse gradient of risk, likely from residual diffuse disease. An FFR-guided revascularization strategy significantly reduces events and increases freedom from angina with fewer procedures than an anatomy-based strategy.

Fractional flow reserve versus angiography for guiding percutaneous coronary intervention: a meta-analysis

Objectives

The purpose of this study was to investigate whether fractional flow reserve (FFR) should be performed for patients with coronary artery disease (CAD) to guide the percutaneous coronary intervention (PCI) strategy.

Background

PCI is the most effective method to improve the outcomes of CAD. However, the proper usage of PCI has not been achieved in clinical practice.

Methods

A meta-analysis was performed on angiography-guided PCI and FFR-guided PCI strategies. Prospective and retrospective studies were included when research subjects were patients with CAD undergoing PCI. The primary endpoint was the rate of major adverse cardiac events (MACE) or major adverse cardiac and cerebrovascular events (MACCE). Secondary endpoints included death, myocardial infarction (MI), repeat revascularisation and death or MI.

Results

Four prospective and three retrospective studies involving 49 517 patients were included. Absolute risks of MACE/MACCE, death, MI, revascularisation and death or MI for angiography-guided PCI and FFR-guided PCI were 34.8% vs 22.5%, 15.3% vs 7.6%, 8.1% vs 4.2%, 20.4% vs 14.8%, and 21.9% vs 11.8%, respectively. The meta-analysis demonstrated that FFR-guided PCI was associated with lower MACE/MACCE (OR: 1.71, 95% CI 1.31 to 2.23), death (OR: 1.64, 95% CI 1.37 to 1.96), MI (OR: 2.05, 95% CI 1.61 to 2.60), repeat revascularisation (OR: 1.25, 95% CI 1.09 to 1.44), and death or MI (OR: 1.84, 95% CI 1.58 to 2.15) than angiography-guided PCI strategy.

Conclusions

This meta-analysis supports current guidelines advising the FFR-guided PCI strategy for CAD. PCI should only be performed when haemodynamic significance is found.

Assessment of coronary blood flow in the cardiac catheterization laboratory

Coronary blood flow is tightly autoregulated but is subject to epicardial and microvascular obstruction, primarily owing to coronary atherosclerosis. Because coronary flow limitation underlies ischemic heart disease, an understanding of coronary physiology is paramount. Measurement of coronary blood flow, once relegated to the research laboratory is now easily performed in the cardiac catheterization laboratory. In particular, the measurement of fractional flow reserve has been extensively studied and is an important adjunct to clinical decision making. Measurement of coronary flow informs clinicians of prognosis, guides revascularization therapy, and forms the basis of ongoing research in treatment of complex myocardial disease processes. Newer methods of assessing coronary flow measurements are undergoing validation for clinical use and should further enhance our ability to assess the importance of coronary flow in clinical disease.

Impact of kissing balloon inflation on the main vessel stent volume, area, and symmetry after side-branch dilation in patients with coronary bifurcation lesions: a serial volumetric intravascular ultrasound study

OBJECTIVES

Intravascular ultrasound (IVUS) was performed to investigate the impact of kissing balloon inflation (KBI) on the main vessel (MV) stent volume, area, and symmetry after side-branch (SB) dilation in patients with coronary bifurcation lesions (CBL).

BACKGROUND

It remains controversial whether KBI would restore the MV stent area and symmetry loss after SB dilation.

METHODS

A total of 88 serial IVUS examinations of the MV were performed after MV angioplasty, MV stenting, SB dilation, and KBI in 22 patients with CBL. The MV stent was divided into proximal, bifurcation, and distal segments; the stent volume index (SVI), minimal stent area (MSA), stent symmetry index (SSI), and external elastic membrane (EEM) volume index were measured in 198 stent segments and compared after MV stenting, SB dilation, and KBI.

RESULTS

In the bifurcation segment, SVI, MSA, and SSI were significantly smaller after SB dilation than after MV stenting and KBI (SVI was 6.10 ± 1.50 mm(3)/mm vs. 6.68 ± 1.60 mm(3)/mm and 6.57 ± 1.60 mm(3)/mm, respectively, p < 0.05; MSA was 5.15 ± 1.30 mm(2) vs. 6.08 ± 1.40 mm(2) and 5.86 ± 1.50 mm(2), respectively, p < 0.05; and SSI was 0.78 ± 0.02 mm(2) vs. 0.87 ± 0.03 mm(2) and 0.84 ± 0.03 mm(2), respectively, p < 0.05). KBI restored the MV SVI, MSA, and SSI after SB dilation. In the proximal segment, SVI, MSA, and EEM volume index were significantly larger, but SSI was smaller after KBI than after MV stenting and SB dilation. In the distal segment, neither SB dilation nor KBI had a significant impact on the MV stent volume or symmetry.

CONCLUSIONS

This is the first comprehensive volumetric IVUS analysis of CBL, to our knowledge, demonstrating that KBI restores the MV stent volume, area, and symmetry loss after SB dilation in the bifurcation segment, and induces asymmetric stent expansion in the proximal segment.

Functional assessment of coronary stenoses: can we live without it?

When selecting coronary stenoses for interventional treatment, assessment of reversible ischaemia is paramount from a symptomatic as well as prognostic point of view. Fractional flow reserve (FFR) is now considered the gold standard for invasive assessment of ischaemia. By measuring FFR in the catheterization laboratory, one can accurately identify which lesions should be stented resulting in improved patient outcome in most elective clinical and angiographic conditions. Recently, in the European Society of Cardiology guidelines on coronary revascularization, FFR was upgraded to an IA classification in multivessel percutaneous coronary intervention. In this review paper, the rationale for routine measurement of FFR will be reviewed and studies supporting its integration into everyday practice will be highlighted.

Coronary pressure-derived fractional flow reserve in the assessment of coronary artery stenoses

OBJECTIVES

Catheter-based angiography is the reference-standard to establish coronary anatomy. While routinely employed clinically, lumen assessment correlates poorly with physiological measures of ischaemia. Moreover, functional studies to identify and localise ischaemia before elective angiography are often not available. This article reviews fractional flow reserve (FFR) and its role in guiding patient management for patients with a potentially haemodynamic significant coronary lesion.

METHODS

This review discusses the theory, evidence, indications, and limitations of FFR. Also included are emerging non-invasive imaging FFR surrogates currently under evaluation for accuracy with respect to standard FFR.

RESULTS

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

CONCLUSIONS

FFR is an invaluable modality in guiding coronary disease treatment decisions. It is safe, cost-effective and leads to improved patient outcomes. Non-invasive imaging modalities to assess the physiologic significance of CAD are currently being  developed and evaluated.

Impact of lesion length on functional significance in intermediate coronary lesions

BACKGROUND

Myocardial fractional flow reserve (FFR) is useful in the evaluation of coronary lesion ischemia. However, the impact of lesion length on FFR has not been adequately assessed.

HYPOTHESIS

We hypothesized that lesion length would influence functional significance in intermediate coronary lesions.

METHODS

FFR measurements were assessed in 136 patients (163 lesions) with stable angina who had >40% stenotic coronary lesion by quantitative coronary angiography (QCA). One hundred sixty-three lesions were classified as intermediate (40%-70% stenosis; n=107; group I) or significant (≥70%; n=56; group S) by QCA. We assessed the relationships between lesion length, coronary stenosis, and FFR in these 163 lesions.

RESULTS

Regression analysis revealed an inverse correlation between the percentage of diameter stenosis (%DS) and FFR in group S (r = -0.83, P < 0.0001). In group I, no significant correlation was found between %DS and FFR (r = -0.06, P = 0.55), whereas lesion length was significantly inversely correlated with FFR (r = -0.79, P < 0.0001). Receiver operating characteristic curve analysis demonstrated that the best cutoff value for predicting an FFR value <0.80 was a lesion length >16.1 mm in group I (sensitivity, 86%; specificity, 94%).

CONCLUSIONS

These study findings suggest that lesion length has a physiologically significant impact on intermediate-grade coronary lesions.

Fractional flow reserve: the past, present and future

Revascularization of coronary artery stenosis should be based on the objective evidence of ischemia. It is common practice for physicians to make decisions on revascularization in the cardiac catheterization laboratory based on the results of angiography, despite the fact that angiographic information does not correlate well with the functional significance of a coronary lesion. Fractional flow reserve (FFR) is a physiologic parameter which can be measured easily during the invasive procedure and can assess the functional significance of coronary stenosis. FFR-guided revascularization strategy is reported to be more effective than angiography-guided strategy in patients with coronary artery disease. Moreover, novel technologies based on FFR have been developed and will soon be incorporated into clinical practice.

Functional measurement of coronary stenosis

Fractional flow reserve (FFR) is considered nowadays as the gold standard for invasive assessment of physiologic stenosis significance and an indispensable tool for decision making in coronary revascularization. Use of FFR in the catheterization laboratory accurately identifies which lesions should be stented and improves the outcome in most elective clinical and angiographic conditions. Recently, FFR has been upgraded to a class IA classification in multivessel percutaneous coronary intervention in the guidelines on coronary revascularization of the European Society of Cardiology. In this state-of-the-art paper, the basic concept of FFR and its application, characteristics, and use in several subsets of patients are discussed from a practical point of view.

Usefulness of minimal luminal coronary area determined by intravascular ultrasound to predict functional significance in stable and unstable angina pectoris

Little is known about the intravascular ultrasound (IVUS) minimal lumen area (MLA) criteria and their accuracy in lesion subsets assorted according to vessel type, lesion location, vessel size, and clinical settings. We therefore assessed the accuracy of subgroup-specific cut-off values in predicting fractional flow reserve (FFR) <0.80. In total 692 consecutive patients with 784 coronary lesions were assessed by IVUS and FFR before intervention. All patients had ≥1 target vessel with a de novo lesion (30% to 90% diameter stenosis). For prediction of FFR <0.80 in the group overall, the best cut-off value of MLA was 2.4 mm(2) (sensitivity 84% and specificity 63%). Overall diagnostic accuracy was only 69%. In the subgroup analysis, the MLA cutoff was 2.4 mm(2) for the left anterior descending coronary artery, 1.6 mm(2) for the left circumflex coronary artery, and 2.4 mm(2) for the right coronary artery. By lesion location, the optimal cutoff was 2.6 mm(2) for proximal, 2.3 mm(2) for mid, and 1.9 mm(2) for distal segments. Furthermore, the cutoffs were 3.2 mm(2) in lesions with a larger RLD >3.5 mm and 1.9 mm(2) in lesions with a smaller RLD <2.75 mm. Nevertheless, diagnostic accuracies of all subgroup-specific criteria were <80%. In conclusion, because IVUS-measured MLA is only 1 of many factors affecting coronary flow hemodynamics, even subgroup-specific criteria were inaccurate in identifying ischemia-inducible stenosis. In conclusion, direct functional assessment is therefore essential in guiding treatment strategies for coronary lesions.

Intravascular ultrasound-derived predictors for fractional flow reserve in intermediate left main disease

OBJECTIVES

The aim of this study was to determine the best intravascular ultrasound (IVUS) criteria for predicting physiological significance of left main (LM) stenosis with fractional flow reserve (FFR) as the standard.

BACKGROUND

For identifying significant LM disease, optimal cutoff of minimal lumen area (MLA) and its accuracy remain debatable.

METHODS

We identified 55 patients (31 stable and 24 unstable angina) with an isolated LM lesion of 30% to 80% angiographic diameter stenosis who underwent IVUS and invasive physiological assessment before intervention.

RESULTS

The FFR at maximum hyperemia significantly correlated with IVUS-measured MLA within the LM (r = 0.623, p < 0.001), plaque burden (r = -0.548, p < 0.001), angiographic diameter stenosis (r = -0.449, p = 0.002), and angiographic length of the lesion (r = -0.292, p = 0.046). The FFR was significantly lower in 18 lesions with plaque rupture than 37 lesions without plaque rupture (0.76 ± 0.09 vs. 0.82 ± 0.09, p = 0.018). The independent determinants of FFR as a continuous variable were MLA (beta = 0.598, p < 0.001) and plaque rupture (beta = -0.255, p = 0.038). Furthermore, the MLA within the LM was the only independent determinant for FFR <0.80 (adjusted odds ratio: 0.312, p < 0.001) and for FFR <0.75 (adjusted odds ratio: 0.196, p = 0.001). The IVUS MLA value within the LM that best predicted FFR <0.80 was <4.8 mm(2) (89% sensitivity, 83% specificity). In addition, the cutoff value of plaque burden to predict FFR <0.80 was ≥72% (73% sensitivity, 79% specificity). The best cutoff values of the MLA and plaque burden for predicting FFR <0.75 were <4.1 mm(2) (95% sensitivity, 83% specificity) and ≥76% (79% sensitivity, 80% specificity), respectively.

CONCLUSIONS

In isolated LM disease, an IVUS-derived MLA <4.8 mm(2) is a useful criterion for predicting FFR <0.80.

Myocardial fractional flow reserve. Its role in guiding PCI in stable coronary artery disease

Revascularization of coronary artery lesions should be based on objective evidence of ischemia, as recommended by the guidelines of the European Society of Cardiology. However, even in the case of stable coronary artery disease and elective percutaneous coronary intervention (PCI), pre-procedural noninvasive stress test results are available in a minority of patients only. It is common practice for physicians to make decisions on revascularization in the catheterization laboratory after a cursory review of the angiogram, despite the well-recognized inaccuracy of such an approach. Myocardial fractional flow reserve (FFR) measured by a coronary pressure wire is a specific index of the functional significance of a coronary lesion, with superior diagnostic accuracy for the detection of ischemia than any noninvasive stress test. FFR trials on patients with single and multivessel disease, such as the DEFER and FAME studies, have demonstrated that the clinical benefit of PCI with respect to patient outcome is greatest when revascularization is limited to lesions inducing ischemia, whereas lesions not inducing ischemia should be treated medically.

Papaverine-induced polymorphic ventricular tachycardia in relation to QTU and giant T-U waves in four cases

OBJECTIVE

Papaverine is used for the evaluation of functional status of the coronary arteries but it may provoke severe ventricular tachyarrhythmias (VTAs). This study compared the clinical and ECG characteristic of patients with papaverine-induced VTAs.

MATERIALS AND METHODS

The study involved 25 patients who underwent a fractional flow reserve (FFR) study. FFR was determined as the ratio of blood pressure at the distal and the proximal site of stenosis after intracoronary papaverine administration at 12 mg into the left and 8 mg into the right coronary artery. The QT and QTU intervals were measured manually in the limb leads and in the precordial leads, respectively and corrected by the R-R interval to obtain QTc and QTUc. The clinical and ECG data were compared between the patient groups with and without VTAs.

RESULTS

After papaverine administration into the left (20), right (3) or both coronary arteries (2), the RR interval shortened, but non-significantly however, the QT interval (and QTc) and the QTU interval (and QTUc) were significantly prolonged. VTAs developed in four women: torsade de pointes in 3 followed by ventricular fibrillation and ventricular premature beats in 1 patient. After papaverine administration, QTU and QTUc were more prolonged in women than men and in patients with VTAs compared to those without. Just prior to VTAs, giant T-U waves were observed.

CONCLUSION

Intracoronary papaverine was used to determine FFR which may induce VTAs. VTAs developed only in women and they were closely related to prolongation of the QTU intervals with prominent T-U waves.

Correlation between fractional flow reserve and intravascular ultrasound lumen area in intermediate coronary artery stenosis

AIMS

Fractional flow reserve (FFR) of <0.8 or 0.75 is currently used to guide revascularisation in lesions with intermediate coronary stenosis. We assessed whether there is an intravascular ultrasound (IVUS) measurement that can reliably be used to predict when patients should undergo intervention.

METHODS AND RESULTS

The analysis included 92 intermediate lesions (84 patients) located in vessel diameters >2.5 mm. Positive FFR was considered present at <0.8 and 0.75. IVUS minimum lumen area (MLA) was correlated to the FFR findings in intermediate lesions with 40-70% stenosis. The mean FFR value was 0.89 ± 0.08. Twenty-four patients (26.1%) had FFR <0.8; 17 (18.5%) <0.75. Positive correlations between FFR and IVUS measurements included MLA (r = 0.34, p<0.001), minimum lumen diameter (MLD) (r=0.31, p=0.004), lesion length (r=-0.5, p<0.001), and area stenosis (r=-0.31, p=0.01). There was no significant correlation between FFR and quantitative coronary angiography in MLD (r=0.19, p=0.06), diameter stenosis (r=0.08, p=0.4), or lesion length (r=-0.14, p=0.17). A receiver operating characteristic curve identified MLA <2.8 mm2 (sensitivity 79.7%, specificity 80.3%) as the best threshold value for FFR <0.75; and MLA <3.2 mm2 as best for FFR <0.8 (sensitivity 69.2%, specificity 68.3%).

CONCLUSIONS

Anatomic measurements of intermediate coronary lesions obtained by IVUS show a moderate correlation to FFR values, although they differ according to vessel size. IVUS MLA may be used as an alternative to FFR when assessing the need for intervention in intermediate coronary lesion. Vessel size, however, should always be taken into account.

Preintervention angiographic and intravascular ultrasound predictors for side branch compromise after a single-stent crossover technique

A single stent crossover technique is the most common approach to treating bifurcation lesions. In 90 bifurcation lesions with side branch (SB) angiographic diameter stenosis <75%, we assessed preintervention intravascular ultrasound (IVUS; of main branch [MB] and SB) predictors for SB compromise (fractional flow reserve [FFR] <0.80) after a single stent crossover. Minimal lumen area (MLA) was measured within each of 4 segments (MB just distal to the carina, polygon of confluence, MB just proximal to polygon of confluence, and SB ostium). All lesions showed Thrombolysis In Myocardial Infarction grade 3 flow in the SB after MB stenting. Although angiographic diameter stenosis at the SB ostium increased from 26 ± 15% before the procedure to 36 ± 21% after stenting (p = 0.001), FFR <0.80 was observed in only 16 patients (18%). Negative remodeling (remodeling index <1) was seen in 83 (92%) lesions but did not correlate with FFR after stenting. Independent predictors for FFR after stenting were maximal balloon pressure (p = 0.002) and MLA of SB ostium before percutaneous coronary intervention (p <0.001), MLA within the MB just distal to the carina (p = 0.025), and plaque burden at the SB ostium before percutaneous coronary intervention (p = 0.005), but not angiographic poststenting diameter stenosis or minimal lumen diameter. For prediction of FFR <0.80 after percutaneous coronary intervention, the best cutoff of MLA within the SB ostium before percutaneous coronary intervention was 2.4 mm(2) (sensitivity 94%, specificity 69%). Also, the cutoff of plaque burden within the SB ostium before percutaneous coronary intervention was ≥51% (sensitivity 75%, specificity 71%). In 67 lesions with an MLA ≥2.4 mm(2) or plaque burden <50% before percutaneous coronary intervention, 63 (94%) showed FFR ≥0.80. However, FFR <0.80 was seen in only 12 (52%) of 23 lesions with an MLA <2.4 mm(2) and plaque burden ≥50%. In conclusion, there do not appear to be reliable IVUS predictors of functional SB compromise after crossover stenting.

[Intermediate lesion and multivessels disease: Interest of fractional flow reserve (FFR) to determine the strategy of revascularization]

Most patients undergoing a catheterization did not have any previous non-invasive testing. Therefore, most decisions about revascularization are taken solely on the basis of the angiogram. Nowadays, it is possible to gain reliable functional information during catheterization by measuring fractional flow reserve (FFR). FFR is obtained by simple pressure measurements distal to the stenosis during maximal hyperemia. FFR-guided revascularization provides better clinical outcomes than angiographically-guided decisions. This is especially relevant in patients with multi-vessel disease and mild to moderate coronary plaque burden. FFR is able to determine the hemodynamic significance of each lesion individually and enables therefore guidance of the revascularization treatment. The case of a 62-year-old man with stable angina is reported. He underwent percutaneous coronary intervention of the left anterior descending 10 years ago. Repeat coronary angiogram revealed multi-vessel disease with a moderate stenosis in all main coronary arteries. Non-invasive functional assessment by myocardial perfusion imaging was inconclusive to evaluate presence or absence of ischemia. The use of FFR in this clinical scenario may be very useful to determine treatment strategy.

Validation of intravascular ultrasound-derived parameters with fractional flow reserve for assessment of coronary stenosis severity

BACKGROUND

We assessed optimal intravascular ultrasound (IVUS) criteria for predicting functional significance of intermediate coronary lesions.

METHODS AND RESULTS

Overall, 201 patients with 236 coronary lesions underwent IVUS and invasive physiological assessment before intervention. Fractional flow reserve (FFR) was measured at maximal hyperemia induced by intravenous adenosine infusion. FFR <0.80 at maximum hyperemia was seen in 49 (21%) of the overall 236 lesions. The independent determinants of FFR were minimal lumen area (MLA; β=0.020; 95% confidence interval [CI], 0.008 to 0.031; P=0.032), plaque burden (β=-0.002; 95% CI, -0.003 to 0.001; P=0.001), lesion length with a lumen area <3.0 mm(2) (β=-0.003; 95% CI, -0.005 to -0.001; P=0.005), and left anterior descending artery location (β=-0.035; 95% CI, -0.055 to -0.016; P=0.001). The best cutoff value (with a maximal accuracy) of the MLA to predict FFR <0.80 was <2.4 mm(2), with a diagnostic accuracy of 68% (90% sensitivity, 60% specificity, and area under the curve=0.800; 95% CI, 0.742 to 0.848; P<0.001). The cutoff value of plaque burden to predict FFR <0.80 was ≥79% (69% sensitivity, 72% specificity, and area under the curve=0.756; 95% CI, 0.696 to 0.810; P<0.001). The cutoff value of lesion length with a lumen area <3.0 mm(2) was 3.1 mm (84%sensitivity, 63%specificity, and area under the curve=0.765; 95% CI, 0.706 to 0.818; P<0.001). Among 117 lesions with an MLA ≥2.4 mm(2), 112 (96%) had an FFR ≥0.80,; and all but 1 showed FFR ≥0.75. Conversely, 44 (37%) lesions with an MLA <2.4 mm(2) had an FFR <0.80.

CONCLUSIONS

IVUS-derived MLA ≥2.4 mm(2) may be useful to exclude FFR <0.80, but poor specificity limits its value for physiological assessment of lesions with MLA <2.4 mm(2). Thus, FFR or stress tests may be necessary to accurately identify ischemia-inducible intermediate stenoses.

Quantification of fractional flow reserve based on angiographic image data

Coronary angiography provides excellent visualization of coronary arteries, but has limitations in assessing the clinical significance of a coronary stenosis. Fractional flow reserve (FFR) has been shown to be reliable in discerning stenoses responsible for inducible ischemia. The purpose of this study is to validate a technique for FFR quantification using angiographic image data. The study was carried out on 10 anesthetized, closed-chest swine using angioplasty balloon catheters to produce partial occlusion. Angiography based FFR was calculated from an angiographically measured ratio of coronary blood flow to arterial lumen volume. Pressure-based FFR was measured from a ratio of distal coronary pressure to aortic pressure. Pressure-wire measurements of FFR (FFR_P) correlated linearly with angiographic volume-derived measurements of FFR (FFR_V) according to the equation: FFR_P = 0.41 FFR_V + 0.52 (P-value < 0.001). The correlation coefficient and standard error of estimate were 0.85 and 0.07, respectively. This is the first study to provide an angiographic method to quantify FFR in swine. Angiographic FFR can potentially provide an assessment of the physiological severity of a coronary stenosis during routine diagnostic cardiac catheterization without a need to cross a stenosis with a pressure-wire.

Economic evaluation of fractional flow reserve-guided percutaneous coronary intervention in patients with multivessel disease

BACKGROUND

The Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) study demonstrated significantly improved health outcomes at 1 year in patients randomized to multivessel percutaneous coronary intervention guided by fractional flow reserve (FFR) compared with percutaneous coronary intervention guided by angiography alone. The economic impact of routine measurement of FFR in this setting is not known.

METHODS AND RESULTS

In this study, 1005 patients were randomly assigned to FFR-guided or angiography-guided percutaneous coronary intervention and followed up for 1 year. A prospective cost-utility analysis comparing costs and quality-adjusted life-years was performed with a time horizon of 1 year. Quality-adjusted life-years were calculated with the use of utilities determined by the EuroQuol 5 dimension health survey with US weights. Direct medical costs included those of the index procedure and hospitalization and costs for major adverse cardiac events during follow-up. Confidence intervals for both quality-adjusted life-years and costs were estimated by the bootstrap percentile method. Major adverse cardiac events at 1 year occurred in 13.2% of those in the FFR-guided arm and 18.3% of those in the angiography-guided arm (P=0.02). Quality-adjusted life-years were slightly greater in the FFR-guided arm (0.853 versus 0.838; P=0.2). Mean overall costs at 1 year were significantly less in the FFR-guided arm ($14 315 versus $16 700; P<0.001). Bootstrap simulation indicated that the FFR-guided strategy was cost-saving in 90.74% and cost-effective at a threshold of US $50 000 per quality-adjusted life-years in 99.96%. Sensitivity analyses demonstrated robust results.

CONCLUSION

Economic evaluation of the FAME study reveals that FFR-guided percutaneous coronary intervention in patients with multivessel coronary disease is one of those rare situations in which a new technology not only improves outcomes but also saves resources. Clinical Trial Registration- URL: http://ClinicalTrials.gov. Unique identifier: NCT00267774.

Fractional flow reserve and myocardial viability as assessed by SPECT perfusion scintigraphy in patients with prior myocardial infarction

BACKGROUND

In patients with previous myocardial infarction (MI), assessment of myocardial viability and physiological significance of coronary artery stenoses are essential for appropriate guidance of revascularization. The aim of the study was to evaluate the relation between fractional flow reserve (FFR) and myocardial viability as assessed by gated SPECT MIBI perfusion scintigraphy in patients with previous MI undergoing elective PCI.

METHODS

The study population consisted of 26 patients (mean age 55 ± 7 years; 21 male) with a previous MI and a significant coronary stenosis in a single infarct-related coronary vessel for which PCI was being performed. In all patients, FFR was evaluated before and immediately after PCI. SPECT imaging was done before and 3 ± 1 months after PCI. A region representing the MI was considered viable if MIBI uptake was ≥55% of the normal region. Improvement in perfusion after revascularization was considered achieved if perfusion abnormalities decreased by 5% or more and there was a decrease in segmental score of ≥1 in three segments in PCI-related vascular territory.

RESULTS

Extent of perfusion abnormalities decreased from 32 ± 16% to 27 ± 19% after PCI (P < .001). In patients with myocardial viability in comparison to patients with no viability, there was significant difference in FFR before PCI (.57 ± .14 vs .76 ± .12, P = .002), despite almost the same values of diameter stenosis of infarct-related artery (63 ± 8% vs 64 ± 3%, respectively, P = .572). In addition, FFR prior to PCI was related to improvement in perfusion abnormalities after revascularization (P = .047), as well as with peak activity of creatine-kinase measured during previous MI (r = .56, P = .005).

CONCLUSION

Lower values of FFR before angioplasty are associated with myocardial viability and functional improvement as assessed by SPECT perfusion scintigraphy.

Angiographic versus functional severity of coronary artery stenoses in the FAME study fractional flow reserve versus angiography in multivessel evaluation

OBJECTIVES

The purpose of this study was to investigate the relationship between angiographic and functional severity of coronary artery stenoses in the FAME (Fractional Flow Reserve Versus Angiography in Multivessel Evaluation) study.

BACKGROUND

It can be difficult to determine on the coronary angiogram which lesions cause ischemia. Revascularization of coronary stenoses that induce ischemia improves a patient's functional status and outcome. For stenoses that do not induce ischemia, however, the benefit of revascularization is less clear.

METHODS

In the FAME study, routine measurement of the fractional flow reserve (FFR) was compared with angiography for guiding percutaneous coronary intervention in patients with multivessel coronary artery disease. The use of the FFR in addition to angiography significantly reduced the rate of all major adverse cardiac events at 1 year. Of the 1,414 lesions (509 patients) in the FFR-guided arm of the FAME study, 1,329 were successfully assessed by the FFR and are included in this analysis.

RESULTS

Before FFR measurement, these lesions were categorized into 50% to 70% (47% of all lesions), 71% to 90% (39% of all lesions), and 91% to 99% (15% of all lesions) diameter stenosis by visual assessment. In the category 50% to 70% stenosis, 35% were functionally significant (FFR <or=0.80) and 65% were not (FFR >0.80). In the category 71% to 90% stenosis, 80% were functionally significant and 20% were not. In the category of subtotal stenoses, 96% were functionally significant. Of all 509 patients with angiographically defined multivessel disease, only 235 (46%) had functional multivessel disease (>or=2 coronary arteries with an FFR <or=0.80).

CONCLUSIONS

Angiography is inaccurate in assessing the functional significance of a coronary stenosis when compared with the FFR, not only in the 50% to 70% category but also in the 70% to 90% angiographic severity category.

Current concepts of integrated coronary physiology in the catheterization laboratory

Over the last 15 years, the use of invasive coronary physiology in the catheterization laboratory has demonstrated favorable outcomes for decision making in patients with intermediate single-vessel stenoses, complex bifurcation and ostial branch stenoses, multivessel coronary artery disease, and left main stenoses. A recent large multicenter study (FAME [FFR versus Angiography for Multivessel Evaluation]) found that a physiologically-guided approach was superior to the standard angiographically-guided approach for percutaneous revascularization in patients with multivessel coronary artery disease. This review addresses selected pertinent concepts and studies supporting the integration of coronary physiology in the catheterization laboratory for optimal patient outcomes.

Coronary pressure measurement based decision making for percutaneous coronary intervention

The fractional flow reserve (FFR) is a simple, reliable, and reproducible physiologic index of lesion severity. In patients with intermediate stenosis, FFR≥0.75 can be used to safely defer percutaneous coronary intervention (PCI), and patients with FFR≥0.75 have a very low cardiac event rate. Coronary pressure measurement can determine which lesion should be treated with PCI in patients with tandem lesions, and PCI on the basis of FFR has been demonstrated to result in an acceptably low repeat PCI rate. FFR can identify patients with equivocal left main coronary artery disease who benefit from coronary bypass surgery. Coronary pressure measurement distinguishes patients with an abrupt pressure drop pattern from those with a gradual pressure drop pattern, and the former group of patients benefit from PCI. Coronary pressure measurement is clinically useful in evaluating sufficient recruitable coronary collateral blood flow for prevention of ischemia, which affects future cardiac events. FFR is useful for the prediction of restenosis after PCI. As an end-point of PCI, FFR ≥0.95 and ≥0.90 would be appropriate for coronary stenting and coronary angioplasty, respectively. In summary, if you encounter a coronary stenosis in doubt you should measure pressure rather than dilate it.

Evaluation of intermediate coronary stenosis with intravascular ultrasound and fractional flow reserve: Its use and abuse

Clinical decision making in patients with intermediate coronary stenosis is still debated. Intravascular ultrasound (IVUS) examination and/or functional assessment of coronary stenosis by fractional flow reserve (FFR) are currently used to define the severity of such lesions. There are very few studies with a small sample size that have a head-to-head comparison between IVUS and FFR in the evaluation of angiographically de novo intermediate lesions. There are no randomized, controlled trials to demonstrate the superiority of IVUS versus FFR in providing improved clinical outcomes in comparison with angiography alone. However, the issue of superiority might be irrelevant, because IVUS and FFR could be complementary techniques to be used in the catheterization laboratory to provide critical anatomic and functional data that permit more accurate decisions in the management of the patient.