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

Sex differences in plaque characteristics of fractional flow reserve-negative non-culprit lesions after myocardial infarction

BACKGROUND AND AIMS

Recurrent events after myocardial infarction (MI) are common and often originate from native non-culprit (NC) lesions that are non-flow limiting. These lesions consequently pose as targets to improve long-term outcome. It is, however, largely unknown whether these lesions differ between sexes. The aim of this study was to assess such potential differences.

METHODS

From the PECTUS-obs study, we assessed sex-related differences in plaque characteristics of fractional flow reserve (FFR)-negative intermediate NC lesions in 420 MI-patients.

RESULTS

Among the included patients, 80 (19.1 %) were female and 340 (80.9 %) male. Women were older and more frequently had hypertension and diabetes. In total, 494 NC lesions were analyzed. After adjustment for clinical characteristics and accounting for within-patients clustering, lesion length was longer in female patients (20.8 ± 10.0 vs 18.3 ± 8.5 mm, p = 0.048) and minimum lumen area (2.30 ± 1.42 vs 2.78 ± 1.54 mm2, p < 0.001) and minimum lumen diameter (1.39 ± 0.45 vs 1.54 ± 0.44 mm, p < 0.001) were smaller. The minimum fibrous cap thickness was smaller among females (96 ± 53 vs 112 ± 72 μm, p = 0.025), with more lesions harboring a thin cap fibroatheroma (39.3 % vs 24.9 %, p < 0.001). Major adverse cardiovascular events at two years occurred in 6.3 % of female patients and 11.8 % of male patients (p = 0.15).

CONCLUSIONS

FFR-negative NC lesions after MI harbored more high-risk plaque features in female patients. Although this did not translate into an excess of recurrent events in female patients in this modestly sized cohort, it remains to be investigated whether this difference affects clinical outcome.

Role of physiology in the management of multivessel disease among patients with acute coronary syndrome

Multivessel coronary artery disease (CAD), defined as ≥50% stenosis in 2 or more epicardial arteries, is associated with a high burden of morbidity and mortality in acute coronary syndrome (ACS) patients. A salient challenge for managing this cohort is selecting the optimal revascularisation strategy, for which the use of coronary physiology has been increasingly recognised. Fractional flow reserve (FFR) is an invasive, pressure wire-based, physiological index measuring the functional significance of coronary lesions. Understanding this can help practitioners evaluate which lesions could induce myocardial ischaemia and, thus, decide which vessels require urgent revascularisation. Non-hyperaemic physiology-based indices, such as instantaneous wave-free ratio (iFR), provide valid alternatives to FFR. While FFR and iFR are recommended by international guidelines in stable CAD, there is ongoing discussion regarding the role of physiology in patients with ACS and multivessel disease (MVD); growing evidence supports FFR use in the latter. Compelling findings show FFR-guided complete percutaneous coronary intervention (PCI) can reduce adverse cardiovascular events, mortality, and repeat revascularisations in ACS and MVD patients compared to angiography-based PCI. However, FFR is limited in identifying non-flow-limiting vulnerable plaques, which can disadvantage high-risk patients. Here, integrating coronary physiology assessment with intracoronary imaging in decision-making can improve outcomes and quality of life. Further research into novel physiology-based tools in ACS and MVD is needed. This review aims to highlight the key evidence surrounding the role of FFR and other functional indices in guiding PCI strategy in ACS and MVD patients.

Three-Year Outcomes With Fractional Flow Reserve-Guided or Angiography-Guided Multivessel Percutaneous Coronary Intervention for Myocardial Infarction

BACKGROUND

In patients with multivessel disease with successful primary percutaneous coronary intervention for ST-segment-elevation myocardial infarction, the FLOWER-MI trial (Flow Evaluation to Guide Revascularization in Multivessel ST-Elevation Myocardial Infarction) showed that a fractional flow reserve (FFR)-guided strategy was not superior to an angiography-guided strategy for treatment of noninfarct-related artery lesions regarding the 1-year risk of death from any cause, myocardial infarction, or unplanned hospitalization leading to urgent revascularization. The extension phase of the trial was planned using the same primary outcome to determine whether a difference in outcomes would be observed with a longer follow-up.

METHODS

In this multicenter trial, we randomly assigned patients with ST-segment-elevation myocardial infarction and multivessel disease with successful percutaneous coronary intervention of the infarct-related artery to receive complete revascularization guided by either FFR (n=586) or angiography (n=577).

RESULTS

After 3 years, a primary outcome event occurred in 52 of 498 patients (9.40%) in the FFR-guided group and in 44 of 502 patients (8.17%) in the angiography-guided group (hazard ratio, 1.19 [95% CI, 0.79-1.77]; P=0.4). Death occurred in 22 patients (4.00%) in the FFR-guided group and in 23 (4.32%) in the angiography-guided group (hazard ratio, 0.96 [95% CI, 0.53-1.71]); nonfatal myocardial infarction in 23 (4.13%) and 14 (2.56%), respectively (hazard ratio, 1.63 [95% CI, 0.84-3.16]); and unplanned hospitalization leading to urgent revascularization in 21 (3.83%) and 18 (3.36%; hazard ratio, 1.15 [95% CI, 0.61-2.16]), respectively.

CONCLUSIONS

Although event rates in the trial were lower than expected, in patients with ST-segment-elevation myocardial infarction undergoing complete revascularization, an FFR-guided strategy did not have a significant benefit over an angiography-guided strategy with respect to the risk of death, myocardial infarction, or urgent revascularization up to 3 years.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02943954.

Fractional flow reserve measurements and long-term mortality-results from the FLORIDA study

Background

Randomized evidence suggested improved outcomes in fractional flow reserve (FFR) guidance of coronary revascularization compared to medical therapy in well-defined patient cohorts. However, the impact of FFR-guided revascularization on long-term outcomes of unselected patients with chronic or acute coronary syndromes (ACS) is unknown.

Aims

The FLORIDA (Fractional FLOw Reserve In cardiovascular DiseAses) study sought to investigate outcomes of FFR-guided vs. angiography-guided treatment strategies in a large, real-world cohort.

Methods

This study included patients enrolled into the German InGef Research Database. Patients undergoing coronary angiography between January 2014 and December 2015 were included in the analysis. Eligible patients had at least one inpatient coronary angiogram for suspected coronary artery disease between January 2014 and December 2015. Patients were stratified into FFR arm if a coronary angiography with adjunctive FFR measurement was performed, otherwise into the angiography-only arm. Matching was applied to ensure a balanced distribution of baseline characteristics in the study cohort. Patients were followed for 3 years after index date and primary endpoint was all-cause mortality.

Results

In the matched population, mortality at 3 years was 9.6% in the FFR-assessed group and 12.6% in the angiography-only group (p = 0.002), corresponding to a 24% relative risk reduction with use of FFR. This effect was most pronounced in patients in whom revascularization was deferred based on FFR (8.7% vs. 12.3%, p = 0.04) and in high-risk subgroups including patients aged ≥75 years (14.9% vs. 20.1%, p < 0.01) and those presenting with ACS (10.2% vs. 14.0%, p = 0.04).

Conclusions

FFR-based revascularization strategy was associated with reduced mortality at 3 years. These findings further support the use of FFR in everyday clinical practice.

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

Background

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

Methods

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

Results

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

Conclusions

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

Contemporary Use of Coronary Physiology in Cardiology

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

Fractional Flow Reserve-Negative High-Risk Plaques and Clinical Outcomes After Myocardial Infarction

Importance

Even after fractional flow reserve (FFR)-guided complete revascularization, patients with myocardial infarction (MI) have high rates of recurrent major adverse cardiovascular events (MACE). These recurrences may be caused by FFR-negative high-risk nonculprit lesions.

Objective

To assess the association between optical coherence tomography (OCT)-identified high-risk plaques of FFR-negative nonculprit lesions and occurrence of MACE in patients with MI.

Design, Setting, and Participants

PECTUS-obs (Identification of Risk Factors for Acute Coronary Events by OCT After STEMI [ST-segment elevation MI] and NSTEMI [non-STEMI] in Patients With Residual Non-flow Limiting Lesions) is an international, multicenter, prospective, observational cohort study. In patients presenting with MI, OCT was performed on all FFR-negative (FFR > 0.80) nonculprit lesions. A high-risk plaque was defined containing at least 2 of the following prespecified criteria: (1) a lipid arc at least 90°, (2) a fibrous cap thickness less than 65 μm, and (3) either plaque rupture or thrombus presence. Patients were enrolled from December 14, 2018, to September 15, 2020. Data were analyzed from December 2, 2022, to June 28, 2023.

Main Outcome and Measure

The primary end point of MACE, a composite of all-cause mortality, nonfatal MI, or unplanned revascularization, at 2-year follow-up was compared in patients with and without a high-risk plaque.

Results

A total of 438 patients were enrolled, and OCT findings were analyzable in 420. Among included patients, mean (SD) age was 63 (10) years, 340 (81.0) were men, and STEMI and non-STEMI were equally represented (217 [51.7%] and 203 [48.3%]). A mean (SD) of 1.17 (0.42) nonculprit lesions per patient was imaged. Analysis of OCT images revealed at least 1 high-risk plaque in 143 patients (34.0%). The primary end point occurred in 22 patients (15.4%) with a high-risk plaque and 23 of 277 patients (8.3%) without a high-risk plaque (hazard ratio, 1.93 [95% CI, 1.08-3.47]; P = .02), primarily driven by more unplanned revascularizations in patients with a high-risk plaque (14 of 143 [9.8%] vs 12 of 277 [4.3%]; P = .02).

Conclusions and Relevance

Among patients with MI and FFR-negative nonculprit lesions, the presence of a high-risk plaque is associated with a worse clinical outcome, which is mainly driven by a higher number of unplanned revascularizations. In a population with a high recurrent event rate despite physiology-guided complete revascularization, these results call for research on additional pharmacological or focal treatment strategies in patients harboring high-risk plaques.

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.

Prognostic impact of fractional flow reserve measurements in patients with acute coronary syndromes: a subanalysis of the FLORIDA study

Randomized trials suggest benefits for fractional flow reserve (FFR)-guided vs. angiography-guided treatment strategies in well-defined and selected patient cohorts with acute coronary syndromes (ACS). The long-term prognostic value of FFR measurement in unselected all-comer ACS patients, however, remains unknown. This subanalysis of the Fractional FLOw Reserve In cardiovascular DiseAses (FLORIDA) study sought to investigate the long-term effects of FFR in the management of lesions in patients with acute coronary syndrome (ACS). FLORIDA was an observational all-comer cohort study performed in Germany, that was population-based and unselected. Patients enrolled into the anonymized InGef Research Database presenting with ACS and undergoing coronary angiography between January 2014 and December 2015 were included in the analysis. Patients were stratified into either the FFR-guided or the angiography-guided treatment arm, based on the treatment received. A matched cohort study design was used. The primary endpoint was all-cause mortality. The secondary endpoint was major adverse cardiovascular events (MACE), a composite of death, non-fatal myocardial infarction (MI), and repeat revascularization. Follow-up time was 3 years. Rates of 3-year mortality were 10.2 and 14.0% in the FFR-guided and the angiography-guided treatment arms (p = 0.04), corresponding to a 27% relative risk reduction for FFR in ACS patients. Rates of MACE were similar in both arms (47.7 vs. 51.5%, p = 0.14), including similar rates of non-fatal MI (27.7 vs. 25.4%, p = 0.47) and revascularization (9.9 vs. 12.1%, p = 0.17). In this large, all-comer observational study of ACS patients, FFR-guided revascularization was associated with a lower mortality at 3 years. This finding encourages the routine use of FFR to guide lesion revascularization in patients presenting with ACS.

Fractional flow reserve and non-hyperemic indices: Essential tools for percutaneous coronary interventions

Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact. Fractional flow reserve (FFR) received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis. FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy, deferring unnecessary procedures for lesions with a FFR > 0.8, improving patients' management and clinical outcome. Post intervention, an optimal FFR > 0.9 post stenting should be reached and > 0.8 post drug eluting balloons. Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89. They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated. FFR remains the gold standard reference for invasive assessment of ischemia. We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio. We conclude introducing a hybrid approach to intermediate lesions (DFR 0.85-0.95) potentially maximizing clinical decision from all measurements.

Optical coherence tomography and coronary revascularization: from indication to procedural optimization

Angiography alone is the most commonly used imaging modality for guidance of percutaneous coronary interventions. Angiography is limited, however, by several factors, including that it only portrays a low resolution, two-dimensional outline of the lumen and does not inform on plaque composition and functional stenosis severity. Optical coherence tomography (OCT) is an intracoronary imaging technique that has superior spatial resolution compared to all other imaging modalities. High-resolution imaging of the vascular wall enables precise measurement of vessel wall and luminal dimensions, more accurately informing about the anatomic severity of epicardial stenoses, and also provides input for computational models to assess functional severity. The very high-resolution images also permit plaque characterization that may be informative for prognostication. Moreover, periprocedural imaging provides valuable information to guide lesion preparation, stent implantation and to evaluate acute stent complications for which iterative treatment might reduce the occurrence of major adverse stent events. As such, OCT represent a potential future all-in-one tool that provides the data necessary to establish the indications, procedural planning and optimization, and final evaluation of percutaneous coronary revascularization.

Current recommendations for revascularization of non-infarct-related artery in patients presenting with ST-segment elevation myocardial infarction and multivessel disease

ST-segment elevation myocardial infarction (STEMI) is a leading cause of morbidity and mortality worldwide. Immediate reperfusion therapy of the infarct-related artery (IRA) is the mainstay of treatment, either via primary percutaneous coronary intervention (PPCI) or thrombolytic therapy when PPCI is not feasible. Several studies have reported the incidence of multivessel disease (MVD) to be about 50% of total STEMI cases. This means that after successful PPCI of the IRA, residual lesion(s) of the non-IRA may persist. Unlike the atherosclerotic plaque of stable coronary artery disease, the residual obstructive lesion of the non-IRA contains a significantly higher prevalence of vulnerable plaques. Since these lesions are a strong predictor of acute coronary syndrome, if left untreated they are a possible cause of future adverse cardiovascular events. Percutaneous coronary intervention (PCI) of the obstructive lesion of the non-IRA to achieve complete revascularization (CR) is therefore preferable. Several major randomized controlled trials (RCTs) and meta-analyses demonstrated the clinical benefits of the CR strategy in the setting of STEMI with MVD, not only for enhancing survival but also for reducing unplanned revascularization. The CR strategy is now supported by recently published clinical practice guidelines. Nevertheless, the benefit of revascularization must be weighed against the risks from additional procedures.

CT Fractional Flow Reserve: A Practical Guide to Application, Interpretation, and Problem Solving

CT fractional flow reserve (FFR_CT) is a physiologic simulation technique that models coronary flow from routine coronary CT angiography (CTA). To evaluate lesion-specific ischemia, FFR_CT is measured 2 cm distal to a stenotic lesion. FFR_CT greater than 0.8 is normal, 0.76-0.8 is borderline, and 0.75 or less is abnormal. FFR_CT should always be interpreted in correlation with clinical and anatomic coronary CTA findings. FFR_CT increases the specificity of coronary CTA in the evaluation of coronary artery disease, decreases the prevalence of nonobstructive disease in invasive coronary angiography (ICA), and helps with revascularization decisions and planning. Patients with intermediate-risk coronary anatomy at CTA and abnormal FFR_CT can undergo ICA and revascularization, whereas those with normal FFR_CT can be safely deferred from ICA. In borderline FFR_CT values, management is decided in the context of the clinical scenario, but many cases could be safely managed with medical treatment. There are some limitations and pitfalls of FFR_CT. Abnormal FFR_CT values can be seen in mild stenosis, and normal FFR_CTvalues can be seen in severe stenosis. Gradually decreasing or abnormal low FFR_CT values at the distal vessel without a proximal focal lesion could be due to diffuse atherosclerosis. Coronary stents, bypass grafts, coronary anomalies, coronary dissection, transcatheter aortic valve replacement, unstable angina, and acute or recent myocardial infarction are situations in which FFR_CT has not been validated and should not be used at this time. The authors provide a practical guide to the applications and interpretation of FFR_CT, focusing on common pitfalls and challenges. Online supplemental material is available for this article. ^©RSNA, 2022.

Instantaneous wave-free ratio for guiding treatment of nonculprit lesions in patients with acute coronary syndrome: A retrospective study

BACKGROUND

The aim of this study was to analyze the feasibility of a physiological coronary evaluation with the instantaneous wave-free ratio (iFR) of nonculprit lesions in patients with acute coronary syndrome (ACS) successfully revascularized.

METHODS

A multicenter registry including patients of four high-volume PCI centers with ACS and underwent successful revascularization of the culprit vessel and had other nonculprit lesions that were physiologically evaluated with the iFR between January 2017 and December 2019. The primary endpoint was a composite of cardiac death, nonfatal myocardial infarction, probable or definitive stent thrombosis and new revascularization (MACEs).

RESULTS

A total of 356 patients with 472 nonculprit lesions were included. The mean age was 66 ± 11 years. The clinical presentation was ACS without persistent ST-segment elevation (NSTE-ACS) in 235 patients (66%) and ST-segment elevation myocardial infarction (STEMI) in 121 patients (34%). After a median follow-up period of 21 (14-30) months, the primary endpoint occurred in 32 patients (9%). There were no differences in outcomes regarding clinical presentation (NSTEMI vs. NSTE-ACS, 9.1 vs. 8.9%, p_adj  = 0.570) or iFR induced treatment strategy (patients with all lesions revascularized vs. patients with at least one lesion with an iFR > 0.89 deferred for revascularization, 10.5 vs. 8.4%, p_adj  = 0.476).

CONCLUSIONS

The use of the iFR to guide percutaneous coronary intervention decision making in nonculprit lesions seems to be feasible, with an acceptable percentage of MACEs at the mid-term follow-up. Patients with deferred revascularization of lesions without physiological significance and patients undergoing complete revascularization had a similar risk of MACEs.

Patients with Moderate Non-Culprit Coronary Lesions of Recent Acute Coronary Syndrome

Fractional flow reserve (FFR) measurement was compared to dobutamine stress echocardiography (DSE) instable angina (SA) with stable coronary lesion (s) (SCL (s) ) in a few trials; however, similar comparisons in patients with acute coronary syndrome (ACS) with non-culprit lesion (s) (NCL (s) ) are lacking. Our objectives were to prospectively evaluate the diagnostic performance of FFR with two different cutoff values (< 0.80 and < 0.75) relative to DSE in moderate (30%-70% diameter stenosis) NCLs (ACS group) and to compare these observations with those measured in SCLs (SA group). One hundred seventy-five consecutive patients with SA (n = 86) and ACS (n = 89) with 225 coronary lesions (109 SCLs and 116 NCLs) were enrolled. In contrast to the ACS cohort in SA patients, normal DSE was associated with higher FFR values compared to those with abnormal DSE (P = 0.051 versus P = 0.006). In addition, in the SA group, a significant correlation was observed between DSE (regional wall motion score index at peak stress) and FFR (r = -0.290; P = 0.002), whereas a similar association was absent (r = -0.029; P = 0.760) among ACS patients. In the SA group, decreasing the FFR cutoff value (< 0.80 versus < 0.75) improved the concordance of FFR with DSE (70.6% versus 81.7%) without altering its discriminatory power (area under the curve; 0.68 versus 0.63; P = 0.369), whereas in the ACS group, concordance remained similar (69.0% versus 71.6%) and discriminatory power decreased (0.62 versus 0.51; P = 0.049), respectively. In conclusion, lesion-specific FFR assessment may have different relevance in patients with moderate NCLs than in patients with SCLs.

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

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

Virtual (Computed) Fractional Flow Reserve: Future Role in Acute Coronary Syndromes

The current management of acute coronary syndromes (ACS) is with an invasive strategy to guide treatment. However, identifying the lesions which are physiologically significant can be challenging. Non-invasive imaging is generally not appropriate or timely in the acute setting, so the decision is generally based upon visual assessment of the angiogram, supplemented in a small minority by invasive pressure wire studies using fractional flow reserve (FFR) or related indices. Whilst pressure wire usage is slowly increasing, it is not feasible in many vessels, patients and situations. Limited evidence for the use of FFR in non-ST elevation (NSTE) ACS suggests a 25% change in management, compared with traditional assessment, with a shift from more to less extensive revascularisation. Virtual (computed) FFR (vFFR), which uses a 3D model of the coronary arteries constructed from the invasive angiogram, and application of the physical laws of fluid flow, has the potential to be used more widely in this situation. It is less invasive, fast and can be integrated into catheter laboratory software. For severe lesions, or mild disease, it is probably not required, but it could improve the management of moderate disease in 'real time' for patients with non-ST elevation acute coronary syndromes (NSTE-ACS), and in bystander disease in ST elevation myocardial infarction. Its practicability and impact in the acute setting need to be tested, but the underpinning science and potential benefits for rapid and streamlined decision-making are enticing.

Coronary CT Angiography in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome

BACKGROUND

In patients with non-ST-segment elevation acute coronary syndrome (NSTEACS), coronary pathology may range from structurally normal vessels to severe coronary artery disease.

OBJECTIVES

The purpose of this study was to test if coronary computed tomography angiography (CTA) may be used to exclude coronary artery stenosis ≥50% in patients with NSTEACS.

METHODS

The VERDICT (Very Early Versus Deferred Invasive Evaluation Using Computerized Tomography in Patients With Acute Coronary Syndromes) trial (NCT02061891) evaluated the outcome of patients with confirmed NSTEACS randomized 1:1 to very early (within 12 h) or standard (48 to 72 h) invasive coronary angiography (ICA). As an observational component of the trial, a clinically blinded coronary CTA was conducted prior to ICA in both groups. The primary endpoint was the ability of coronary CTA to rule out coronary artery stenosis (≥50% stenosis) in the entire population, expressed as the negative predictive value (NPV), using ICA as the reference standard.

RESULTS

Coronary CTA was conducted in 1,023 patients-very early, 2.5 h (interquartile range [IQR]: 1.8 to 4.2 h), n = 583; and standard, 59.9 h (IQR: 38.9 to 86.7 h); n = 440 after the diagnosis of NSTEACS was made. A coronary stenosis ≥50% was found by coronary CTA in 68.9% and by ICA in 67.4% of the patients. Per-patient NPV of coronary CTA was 90.9% (95% confidence interval [CI]: 86.8% to 94.1%) and the positive predictive value, sensitivity, and specificity were 87.9% (95% CI: 85.3% to 90.1%), 96.5% (95% CI: 94.9% to 97.8%) and 72.4% (95% CI: 67.2% to 77.1%), respectively. NPV was not influenced by patient characteristics or clinical risk profile and was similar in the very early and the standard strategy group.

CONCLUSIONS

Coronary CTA has a high diagnostic accuracy to rule out clinically significant coronary artery disease in patients with NSTEACS.

Complete or Incomplete Revascularization for ST-Segment Elevation Myocardial Infarction: The PRAMI Trial to COMPLETE

Many patients presenting with ST-segment elevation myocardial infarction (STEMI) have multivessel coronary artery disease (CAD). Following successful primary percutaneous coronary intervention (PCI) of culprit lesion, whether to routinely revascularize nonculprit lesions or treat them medically has been debated. Recently, the large-scale, multinational COMPLETE trial definitively established benefit of routine, staged, angiographically guided nonculprit lesion PCI in reducing hard clinical outcomes, including the composite of death from cardiovascular causes or new myocardial infarction, with no major safety concerns. A strategy of complete revascularization with routine nonculprit lesion PCI in suitable lesions should be standard of care in STEMI with multivessel CAD.

Management of non-culprit coronary plaques in patients with acute coronary syndrome

Approximately 50% of patients with ST-segment elevation myocardial infarction (STEMI) have multivessel coronary artery disease, a condition associated with an increased incidence of recurrent ischaemic events and higher mortality. Based on recent evidences, a strategy of staged percutaneous coronary intervention (PCI) of obstructive non-culprit lesions should be considered the gold standard for the management of these patients. However, several issues remain still unresolved. Indeed, what is the optimal timing of staged PCI is not completely defined. Moreover, assessment of intermediate non-culprit lesions represent still a clinical conundrum, as pressure-wire indexes do not seem able to correctly identify those patients in whom deferral is safe. Intracoronary imaging may help to identify untreated non-culprit lesions containing vulnerable plaques that may portend a higher risk of future cardiovascular events. However, there are hitherto no studies demonstrating that preventive PCI of vulnerable plaques or more intensive pharmacological treatment is associated with an improved clinical outcome. In this review, we discuss the recent evolving concepts about management of non-culprit plaques in STEMI patients, proposing a diagnostic and therapeutic algorithm to guide physicians in clinical practice. We also underscore the several knowledge gaps to address in future studies.

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The Role of Fractional Flow Reserve and Instantaneous Wave-Free Ratio Measurements in Patients with Acute Coronary Syndrome

PURPOSE OF REVIEW

The role of fractional flow reserve to guide revascularization in patients with stable angina is well established. The instantaneous wave-free ratio (iFR) is an emerging adenosine-free resting index that is non-inferior to FFR and has potential to streamline the functional evaluation of coronary artery disease. The feasibility and utility of intracoronary physiology in patients with acute coronary syndrome (ACS) is unclear. This review will discuss the physiological principles and validity of using FFR and iFR in patients presenting with ACS. We will also provide an overview of the available evidence for their role in guiding revascularization in this patient group.

RECENT FINDINGS

The use of intracoronary physiology in culprit lesions of patients presenting with STEMI is not recommended and its accuracy is uncertain in patients with NSTEMI. In contrast, the physiological assessment of non-culprit vessels with FFR and IFR is a reliable measure of lesion-specific ischemia. Recent studies have demonstrated that FFR-guided revascularization of non-culprit lesions improves clinical outcomes although the role of iFR in this patient cohort is unknown. Physiology-guided revascularization of non-culprit ACS lesions improves clinical outcomes. Future studies investigating the complementary role of plaque morphology, biomechanics, and systemic inflammation may provide clinicians with a more comprehensive framework to guide treatment decisions.