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Background: The clinical impact of a chronic total occlusion (CTO) in patients with 3-vessel coronary artery disease undergoing fractional flow reserve-guided percutaneous coronary intervention (PCI) with current-generation drug-eluting stents or coronary artery bypass grafting (CABG) is unclear., Methods: The FAME 3 trial (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation 3) compared fractional flow reserve-guided PCI with CABG in patients with 3-vessel coronary artery disease. The primary end point was major adverse cardiac and cerebrovascular events, a composite of death, myocardial infarction, stroke, or repeat revascularization at 1 year. In this substudy, the 3-year outcomes were analyzed in patients with or without a CTO., Results: Of the patients randomized to PCI or CABG in the FAME 3 trial, 305 (21%) had a CTO. In the PCI arm, revascularization of the CTO was attempted in 61% with a procedural success rate of 88%. The incidence of major adverse cardiac and cerebrovascular events at 3 years was not significantly different between those with or without a CTO in both the PCI (15.2% versus 20.1%; adjusted hazard ratio, 0.62 [95% CI, 0.38-1.03]; P =0.07) and the CABG (13.0% versus 12.9%; adjusted hazard ratio, 0.96 [95% CI, 0.55-1.66]; P =0.88) arms. In those without a CTO, PCI was associated with a significantly higher risk of major adverse cardiac and cerebrovascular events compared with CABG (adjusted hazard ratio, 1.61 [95% CI, 1.20-2.17]; P <0.01) but not in those with a CTO (adjusted hazard ratio, 1.21 [95% CI, 0.64-2.28]; P =0.56; P interaction =0.31)., Conclusions: The presence of a CTO did not significantly impact the treatment effect of PCI versus CABG at 3 years in patients with 3-vessel coronary artery disease., Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02100722.

Background: Continuous intracoronary thermodilution with saline allows for the accurate measurement of volumetric blood flow (Q) and absolute microvascular resistance (R μ ). However, this requires repositioning of the temperature sensor by the operator to measure the entry temperature of the saline infusate, denoted as T i ., Aims: We evaluated whether Ti could be predicted based on known parameters without compromising the accuracy of calculated Q. This would significantly simplify the technique and render it completely operator independent., Methods: In a derivation cohort of 371 patients with Q measured both at rest and during hyperaemia, multivariate linear regression was used to derive an equation for the prediction of T i . Agreement between standard Q (calculated with measured T i ) and simplified Q (calculated with predicted T i ) was assessed in a validation cohort of 120 patients that underwent repeat Q measurements. The accuracy of simplified Q was assessed in a second validation cohort of 23 patients with [ 15 O]H 2 O positron emission tomography (PET)-derived Q measurements., Results: Simplified Q exhibited strong agreement with standard Q (r=0.94, confidence interval [CI]: 0.93-0.95; intraclass correlation coefficient [ICC] 0.94, CI: 0.92-0.95; both p<0.001). Simplified Q exhibited excellent agreement with PET-derived Q (r=0.86, CI: 0.75-0.92; ICC=0.84, CI: 0.72-0.91; both p<0.001). Compared with standard Q, there were no statistically significant differences between correlation coefficients (p=0.29) or standard deviations of absolute differences with PET-derived Q (p=0.85)., Conclusions: Predicting T i resulted in an excellent agreement with measured T i for the assessment of coronary blood flow. It significantly simplifies continuous intracoronary thermodilution and renders absolute coronary flow measurements completely operator independent.

Background: Coronary disease complexity is commonly used to guide revascularization strategy in patients with multivessel disease (MVD)., Objectives: The aim of this study was to assess the interactive effects of coronary complexity on percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) outcomes and identify the optimal threshold at which PCI can be considered a reasonable option., Methods: A total of 1,444 of 1,500 patients with MVD from the FAME (Fractional Flow Reserve versus Angiography for Multi-vessel Evaluation) 3 randomized trial were included in the analysis (710 CABG vs 734 PCI). SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) scores were transformed into restricted cubic splines, and logistic regression models were fitted, with multiplicative interaction terms for revascularization strategy. Optimal thresholds at which PCI is a reasonable alternative to CABG were determined on the basis of Cox regression model performance., Results: The mean SYNTAX score (SS) was 25.9 ± 7.1. SS was associated with 1-year major adverse cardiac and cerebrovascular events among PCI patients and 3-year death, myocardial infarction, and stroke among CABG patients. Significant interactions were present between revascularization strategy and SS for 1- and 3-year composite endpoints (P for interaction <0.05 for all). In Cox regression models, outcomes were comparable between CABG and PCI for the 3-year primary endpoint for SS ≤24 (P = 0.332), with 44% of patients below this threshold and 32% below the conventional SS threshold of ≤22., Conclusions: In patients with MVD without left main disease, PCI and CABG outcomes remain comparable up to SS values in the mid- rather than low 20s, which allows the identification of a greater proportion of patients in whom PCI may be a reasonable alternative to CABG., Competing Interests: Funding Support and Author Disclosures This work was supported by grants from Medtronic and Abbott Vascular. Dr Dawson is supported by the Australian National Health and Medical Research Council and the Australian National Heart Foundation postgraduate scholarships. Dr Kobayashi serves as a consultant for Abbott Vascular. Dr Fearon has received institutional research support from Abbott Vascular, and Medtronic; and has stock options with HeartFlow. Dr De Bruyne has consulting relationships with Boston Scientific, Abbott Vascular, CathWorks, Siemens, and Coroventis Research; has received research grants from Abbott Vascular, Coroventis Research, CathWorks, and Boston Scientific; and holds minor equities in Philips-Volcano, Siemens, GE Healthcare, Edwards Lifesciences, HeartFlow, Sanofi, and Celyad. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Diffuse coronary artery disease affects the safety and efficacy of percutaneous coronary intervention (PCI). Pathophysiologic coronary artery disease patterns can be quantified using fractional flow reserve (FFR) pullbacks incorporating the pullback pressure gradient (PPG) calculation. This study aimed to establish the capacity of PPG to predict optimal revascularization and procedural outcomes., Methods: This prospective, investigator-initiated, single-arm, multicenter study enrolled patients with at least one epicardial lesion with an FFR ≤0.80 scheduled for PCI. Manual FFR pullbacks were used to calculate PPG. The primary outcome of optimal revascularization was defined as an FFR ≥0.88 after PCI., Results: A total of 993 patients with 1044 vessels were included. The mean FFR was 0.68±0.12, PPG 0.62±0.17, and the post-PCI FFR was 0.87±0.07. PPG was significantly correlated with the change in FFR after PCI (r=0.65 [95% CI, 0.61-0.69]; P <0.001) and demonstrated excellent predictive capacity for optimal revascularization (area under the receiver operating characteristic curve, 0.82 [95% CI, 0.79-0.84]; P <0.001). FFR alone did not predict revascularization outcomes (area under the receiver operating characteristic curve, 0.54 [95% CI, 0.50-0.57]). PPG influenced treatment decisions in 14% of patients, redirecting them from PCI to alternative treatment modalities. Periprocedural myocardial infarction occurred more frequently in patients with low PPG (<0.62) compared with those with focal disease (odds ratio, 1.71 [95% CI, 1.00-2.97])., Conclusions: Pathophysiologic coronary artery disease patterns distinctly affect the safety and effectiveness of PCI. PPG showed an excellent predictive capacity for optimal revascularization and demonstrated added value compared with an FFR measurement., Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04789317., Competing Interests: Dr Collet reports receiving research grants from Biosensors, Coroventis Research, Medis Medical Imaging, Pie Medical Imaging, CathWorks, Boston Scientific, Siemens, HeartFlow, and Abbott Vascular; consultancy fees from HeartFlow, OpSens Medical, Abbott Vascular, and Philips Volcano; and has patents pending on diagnostic methods for coronary artery disease. Dr Munhoz reports a research grant provided by the CardioPath PhD programme and speaker fees from Abbott Vascular. Dr Mizukami reports receiving research grants from Boston Scientific and speaker fees from Abbott Vascular, CathWorks, and Boston Scientific. Dr Matsuo has received consulting fees from Kaneka and Zeon and speaker’s fees from Abbott Medical Japan, Boston Scientific, Philips, and Amgen. Dr Ko has received consulting fees from Canon Medical, Abbott, and Medtronic. Dr Biscaglia received research grants provided by Sahajanand Medical Technologies, Medis Medical Imaging, Eukon Srl, Siemens Healthineers, General Electric Healthcare, and Insight Lifetech. Dr Engstrøm reports speaker and advisory board fees from Abbott, Boston Scientific, and Novo Nordisk. Dr Leone reports receiving consultancy fees from Abbott and honoraria for sponsored symposia from Abbott, Medtronic, and Abiomed. Dr Fearon receives institutional research support from Abbott, Boston Scientific, and Medtronic and has consulting relationships with CathWorks and Siemens and stock options from HeartFlow. Dr Christiansen has received consulting fees from Abbott Medical Denmark A/S. Dr Yong has received minor honoraria from Abbott Vascular and research grants from Abbott Vascular and Philips. Dr Escaned is supported by the Intensification of Research Activity project INT22/00088 from the Spanish Instituto de Salud Carlos III and received speaker and advisory board member fees from Abbott and Philips. Dr Storozhenko reports a grant provided by the EAPCI Fellowship Programme. Dr West is an employee of Abbott Vascular. Dr De Potter is a paid consultant for Biosense Webster and receives grant support (institutional) and consultancy fees (institutional) from Abbott. Dr Berry receives research funding from the British Heart Foundation (grants RE/18/6134217, BHF/FS/17/26/32744, and PG/19/28/34310) and is employed by the University of Glasgow, which holds consultancy and research agreements for his work with Abbott Vascular, AstraZeneca, Boehringer Ingelheim, Coroventis Research, GlaxoSmithKline, HeartFlow, Menarini, Novartis, Servier, Siemens Healthcare, and Valo Health. Dr Collison has received consulting fees from Abbott. Dr Johnson has received consultancy or speaker fees from Abbott Vascular, Boston Scientific, Medtronic, Shockwave, and Terumo, and research grants from Abbott Vascular. Dr Amano reports receiving lecture fees from Astellas Pharma, Astra Zeneca, Bayer, Daiichi Sankyo, and Bristol Myers Squibb. Dr Perera has received research grant support from Abbott Vascular, HeartFlow, and Philips. Dr Jeremias has received consulting fees from Canon Medical, Artrya Medical, and Boston Scientific. Dr Ali reports institutional grant support from Abbott, Abiomed, Acist, Amgen, Boston Scientific, CathWorks, Canon Medical, Conavi, HeartFlow, Inari, Medtronic, the US National Institutes of Health, Nipro, OpSens Medical, Medis, Philips, Shockwave, Siemens, SpectraWAVE, and Teleflex; consulting fees from Abiomed, Astra Zeneca, Boston Scientific, CathWorks, OpSens Medical, Philips, and Shockwave; and equity in Elucid, Lifelink, SpectraWAVE, Shockwave, and VitalConnect. Dr Pijls has received research grants from Abbott and Hexacath; consultancy fees from Abbott, GE, Philips, and HeartFlow; and has equity in General Electric, Philips, and HeartFlow. Dr De Bruyne reports receiving consultancy fees from Boston Scientific and Abbott and research grants from Coroventis Research, Pie Medical Imaging, CathWorks, Boston Scientific, Siemens, HeartFlow, and Abbott Vascular. Dr Johnson received internal funding from the Weatherhead PET Center for Preventing and Reversing Atherosclerosis; has received significant institutional research support from St Jude Medical (CONTRAST [Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology?; URL: https://www.clinicaltrials.gov; Unique identifier: NCT02184117]) and Philips Volcano (DEFINE-FLOW [Combined Pressure and Flow Measurements to Guide Treatment of Coronary Stenoses; URL: https://www.clinicaltrials.gov; Unique identifier: NCT02328820]) for other studies using intracoronary pressure and flow sensors; has an institutional licensing agreement with Boston Scientific for the smart-minimum FFR algorithm (now commercialized under 510[k] K191008); and has patents pending on diagnostic methods for quantifying aortic stenosis and TAVI physiology and on methods to correct pressure tracings from fluid-filled catheters.

Background: The optimal index of microvascular function should be specific for the microvascular compartment. Yet, coronary flow reserve (CFR), despite being widely used to diagnose coronary microvascular dysfunction (CMD), is influenced by both epicardial and microvascular resistance. Conversely, microvascular resistance reserve (MRR) adjusts for fractional flow reserve (FFR), and thus is theoretically independent of epicardial resistance., Objectives: The authors tested the hypothesis that MRR, unlike CFR, is not influenced by increasing epicardial resistance, and thus is a more specific index of microvascular function., Methods: In a cohort of 16 patients who had undergone proximal left anterior descending artery stenting, we created 4 grades of artificial stenosis (no stenosis, mild, moderate, and severe) using a coronary angioplasty balloon inflated to different degrees within the stent. For each stenosis grade, we calculated CFR and MRR using continuous thermodilution (64 measurements of each) to assess their response to changing epicardial resistance., Results: Graded balloon inflation resulted in a significant sequential decrease in mean FFR (no stenosis: 0.82 ± 0.05; mild: 0.72 ± 0.04; moderate: 0.61 ± 0.05; severe: 0.48 ± 0.09; P < 0.001). This translated into a linear decrease in mean hyperemic coronary flow (no stenosis: 170.5 ± 66.8 mL/min; mild: 149.8 ± 58.8 mL/min; moderate: 124.4 ± 53.0 mL/min; severe: 94.0 ± 45.2 mL/min; P < 0.001). CFR exhibited a marked linear decrease with increasing stenosis (no stenosis: 2.5 ± 0.9; mild: 2.2 ± 0.8; moderate: 1.8 ± 0.7; severe: 1.4 ± 0.6), corresponding to a decrease of 0.3 for a decrease in FFR of 0.1 (P < 0.001). In contrast, MRR exhibited a negligible decrease across all stenosis grades (no stenosis: 3.0 ± 1.0; mild: 3.0 ± 1.0; moderate: 2.9 ± 1.0; severe: 2.8 ± 1.0), corresponding to a decrease of just 0.05 for a decrease in FFR of 0.1 (P < 0.001)., Conclusions: MRR, unlike CFR, is minimally influenced by epicardial resistance, and thus should be considered the more specific index of microvascular function. This suggests that MRR can also reliably evaluate microvascular function in patients with significant epicardial disease., Competing Interests: Funding Support and Author Disclosures Dr Mahendiran is supported by a grant from the Swiss National Science Foundation. Drs Bertolone, Viscusi, and Wilgenhof have received research grants provided by the Cardiopath PhD program. Dr Collet has received research grants from Biosensor, Coroventis Research, Medis Medical Imaging, Pie Medical Imaging, CathWorks, Boston Scientific, Siemens, HeartFlow Inc, and Abbott Vascular; and has received consultancy fees from HeartFlow Inc, OpSens, Abbott Vascular, and Philips Volcano. Dr Pijls has received institutional research grants from Abbott; has consulting relationships with and receives fees from Abbott and Coroventis; has equity in ASML, General Electric, HeartFlow, and Philips; is a member of the Scientific Advisory Board of Heartflow; and has patents pending in the field of the coronary microcirculation and aortic valve stenosis. Dr De Bruyne has a consulting relationship with Boston Scientific, Abbott Vascular, CathWorks, Siemens, and Coroventis Research; has received research grants from Abbott Vascular, Coroventis Research, Cathworks, Boston Scientific; and holds minor equities in Philips-Volcano, Siemens, GE Healthcare, Edwards Lifesciences, HeartFlow, Sanofi, and Celyad. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: In 5%-25% of non-ST-elevation acute coronary syndrome (NSTE-ACS) patients, coronary angiography reveals no obstructive coronary arteries (MINOCA). Coronary microvascular disease (CMD) is a potential causal pathophysiological mechanism in these patients and can be diagnosed by continuous thermodilution assessment. Recently, the microvascular resistance reserve (MRR) has been introduced as a novel index to assess the vasodilatory capacity of the microcirculation. However, continuous thermodilution and MRR have never been investigated in the acute setting in MINOCA patients and invasive assessment of the microcirculation in these patients are currently lacking., Aims: The objectives of the study were to investigate the incidence of CMD (MRR ≤ 2.7) in patients with MINOCA and to evaluate the feasibility and safety of continuous thermodilution-based assessment during index coronary angiography in the acute setting., Methods: This study was a prospective, observational, pilot study investigating coronary physiology in the acute setting in MINOCA patients. Patients admitted with a diagnosis of NSTE-ACS were eligible for inclusion., Results: In total, 19 MINOCA patients were included in this analysis; the mean age was 70 ± 9 years, and 79% were females. CMD was present in 6 patients (32%). Q rest was significantly higher in the MRR ≤ 2.7 group compared to the MRR > 2.7 group (0.076 [0.057-0.100] vs. 0.049 [0.044-0.071] L/min, p = 0.03). R µ,rest was significantly lower in the MRR ≤ 2.7 group compared to the MRR > 2.7 group (1083 [710-1510] vs. 1563 [1298-1970] WU, p = 0.04). No periprocedural complications or hemodynamic instability have occurred during continuous thermodilution assessment during the index coronary angiography., Conclusion: In patients admitted for MINOCA undergoing immediate coronary angiography, continuous thermodilution assessment and MRR are feasible and safe in the acute setting, and evidence of functional CMD could be observed in one-third of the MINOCA patients., (© 2024 The Author(s). Catheterization and Cardiovascular Interventions published by Wiley Periodicals LLC.)

Background: While experimental data suggest that selective intracoronary hypothermia decreases infarct size, studies in patients with ST-elevation myocardial infarction (STEMI) are lacking., Aims: We investigated the efficacy of selective intracoronary hypothermia during primary percutaneous coronary intervention (PCI) to decrease infarct size in patients with STEMI., Methods: In this multicentre randomised controlled trial, 200 patients with large anterior wall STEMI were randomised 1:1 to selective intracoronary hypothermia during primary PCI or primary PCI alone. Using an over-the-wire balloon catheter for infusion of cold saline and a pressure-temperature wire to monitor the intracoronary temperature, the anterior myocardium distal to the occlusion was selectively cooled to 30-33°C for 7-10 minutes before reperfusion (occlusion phase), immediately followed by 10 minutes of cooling after reperfusion (reperfusion phase). The primary endpoint was infarct size as a percentage of left ventricular mass on cardiovascular magnetic resonance imaging after 3 months., Results: Selective intracoronary hypothermia was performed in 94/100 patients randomised to cooling. Distal coronary temperature decreased by 6°C within 43 seconds (interquartile range [IQR] 18-113). The median duration of the occlusion phase and reperfusion phase were 8.2 minutes (IQR 7.2-9.0) and 9.1 minutes (IQR 8.2-10.0), respectively. The infarct size at 3 months was 23.1±12.5% in the selective intracoronary hypothermia group and 21.6±12.2% in the primary PCI alone group (p=0.43). The left ventricular ejection fraction at 3 months in each group were 49.1±10.2% and 50.1±10.4%, respectively (p=0.53)., Conclusions: Selective intracoronary hypothermia during primary PCI in patients with anterior wall STEMI was feasible and safe but did not decrease infarct size compared with standard primary PCI. (ClinicalTrials.gov: NCT03447834).

Background: The microvascular resistance reserve (MRR) has recently been introduced as a novel index to assess the vasodilatory capacity of the microcirculation, independent of epicardial disease. The prognostic value of MRR in ST-segment elevation myocardial infarction (STEMI) is unknown., Objectives: The aim of this analysis was to investigate the prognostic value of MRR in patients with STEMI and to compare MRR with cardiovascular magnetic resonance imaging parameters., Methods: From a pooled analysis of individual patient data from 6 cohorts that measured the index of microcirculatory resistance (IMR) directly after primary percutaneous coronary intervention in patients with STEMI (n = 1,265), a subgroup analysis was performed in patients in whom both MRR and IMR were available. The primary endpoint was the composite of all-cause mortality or hospitalization for heart failure., Results: Both MRR and IMR could be calculated in 446 patients. The optimal cutoff of MRR to predict the primary endpoint in this STEMI population was 1.25. During a median follow-up of 3.1 years (Q1-Q3: 1.5-6.1 years), the composite of all-cause mortality or hospitalization for heart failure occurred in 27.3% and 5.9% of patients (HR: 4.16; 95% CI: 2.31-7.50; P < 0.001) in the low MRR (≤1.25) and high MRR (>1.25) groups, respectively. Both IMR and MRR were independent predictors of the composite of all-cause mortality or hospitalization for heart failure., Conclusions: MRR measured directly after primary percutaneous coronary intervention was an independent predictor of the composite of all-cause mortality or hospitalization for heart failure during long-term follow-up., Competing Interests: Funding Support and Author Disclosures Dr De Maria has received consultancy fees from Miracor Medical SA and Corflow; and has received grants from Abbott, Philips, Medtronic, Terumo, Miracor Medical SA, and Opsens. Dr van Royen has received research grants from Philips, Abbott, Medtronic, and Biotronik; and has received speaker fees from Abbott, Bayer, Rainmed, and Microport. Dr van Leeuwen has received speakers/consulting services honoraria from Terumo, Daiichi-Sankyo, and Abbott; and has received research grants from AstraZeneca, Top Sector Life Sciences & Health, Terumo, Top Medical B.V., and Abbott. Dr Pijls has received institutional research grants from Abbott and Hexacath; is a consultant for Abbott and Opsens; holds minor equity interest in Philips, ASML, HeartFlow, and GE; is a member of the scientific advisory board for HeartFlow; and has patents pending on diagnostic methods for quantifying aortic valve stenosis and microvascular physiology. Dr Fineschi has received speaker honoraria and consulting fees from St Jude Medical Italia (now Abbott). Dr Oldroyd has received honoraria from Abbott, Biosensors International, and Boston Scientific; has received an institutional research grant from Boston Scientific that supported the present manuscript; and has been a full-time employee of Biosensors International since May 2020. Dr Berry has received institutional grants/contracts from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Novartis, Siemens Healthcare; has received consulting fees from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Menarini, and Novartis; and has received honoraria from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Philips, and Valo Health. Dr Fearon has received research support from Abbott, Boston, Edwards, and Medtronic; has consulting agreements with CathWorks and Siemens; and has equity options with HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: Prehospital risk stratification and triage are currently not performed in patients suspected of non-ST-segment elevation acute coronary syndrome (NSTE-ACS). This may lead to prolonged time to revascularisation, increased duration of hospital admission and higher healthcare costs. The preHEART score (prehospital history, ECG, age, risk factors and point-of-care troponin score) can be used by emergency medical services (EMS) personnel for prehospital risk stratification and triage decisions in patients with NSTE-ACS. The aim of the current study was to evaluate the effect of prehospital risk stratification and direct transfer to a percutaneous coronary intervention (PCI) centre, based on the preHEART score, on time to final invasive diagnostics or culprit revascularisation., Methods: Prospective, multicentre, two-cohort study in patients with suspected NSTE-ACS. The first cohort is observational (standard care), while the second (interventional) cohort includes patients who are stratified for direct transfer to either a PCI or a non-PCI centre based on their preHEART score. Risk stratification and triage are performed by EMS personnel. The primary endpoint of the study is time from first medical contact until final invasive diagnostics or revascularisation. Secondary endpoints are time from first medical contact until intracoronary angiography (ICA), duration of hospital admission, number of invasive diagnostics, number of inter-hospital transfers and major adverse cardiac events at 7 and 30 days., Results: A total of 1069 patients were included. In the interventional cohort (n=577), time between final invasive diagnostics or revascularisation (42 (17-101) hours vs 20 (5-44) hours, p<0.001) and length of hospital admission (3 (2-5) days vs 2 (1-4) days, p=0.007) were shorter than in the observational cohort (n=492). In patients with NSTE-ACS in need for ICA or revascularisation, healthcare costs were reduced in the interventional cohort (€5599 (2978-9625) vs €4899 (2278-5947), p=0.02)., Conclusion: Prehospital risk stratification and direct transfer to a PCI centre, based on the preHEART score, reduces time from first medical contact to final invasive diagnostics and revascularisation, reduces duration of hospital admission and decreases healthcare costs in patients with NSTE-ACS in need for ICA or revascularisation., Trial Registration: NCT05243485., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Diagnosing coronary microvascular dysfunction remains challenging, primarily due to the lack of direct measurements of absolute coronary blood flow (Q) and microvascular resistance (R μ ). However, there has been recent progress with the development and validation of continuous intracoronary thermodilution, which offers a simplified and validated approach for clinical use. This technique enables direct quantification of Q and R μ , leading to precise and accurate evaluation of the coronary microcirculation. To ensure consistent and reliable results, it is crucial to follow a standardized protocol when performing continuous intracoronary thermodilution measurements. This document aims to summarize the principles of thermodilution-derived absolute coronary flow measurements and propose a standardized method for conducting these assessments. The proposed standardization serves as a guide to ensure the best practice of the method, enhancing the clinical assessment of the coronary microcirculation., Competing Interests: Funding Support and Author Disclosures Drs Belmonte, Bertolone, and Viscusi are supported by a research grant from the CardioPaTh PhD Program. Dr Pijls has received institutional research grants from Abbott; has consulting relationships with and receives fees from Abbott and Coroventis; has equity in ASML, General Electric, HeartFlow, and Philips; is a member of the Scientific Advisory Board of Heartflow; and has patents pending in the field of the coronary microcirculation and aortic valve stenosis. Dr Mizukami has received consulting fees from Zeon Medical and HeartFlow; and has received speaker fees from Abbott Vascular. Dr Barbato has received speaker fees from Abbott Vascular, Boston Scientific, and GE. Dr Dannab has received grants from Philips, Abbott, and AstraZeneca; and has received consulting fees from Philips. Dr Keeble has received honoraria and institutional research funding from Abbott Vascular, Medtronic, Terumo, Zoll, and Shockwave; has received consulting fees from BD; has received speaker fees from Cardionovum, Abbott Vascular, and AstraZeneca; is on the steering group for the ORBITA-2 trial; and is on the committee for the National Institute for Health and Care Research Invention for Innovation (i4i), British Cardiovascular Intervention Society and Resuscitation Council. Dr Kern is a speaker for Abbott Vascular, Boston Scientific, Acist, Opsens, and Zoll. Dr Fearon has received institutional research support from Abbott, Boston Scientific, and Medtronic; has a consulting relationship with CathWorks and Siemens; and has stock options with HeartFlow. Dr Collet has received research grants from Biosensors, HeartFlow, and Abbott Vascular; and has received consultancy fees from HeartFlow, Abbott Vascular, Boston Scientific, Opsens, and Philips Volcano. Dr De Bruyne has consulting relationships with Boston Scientific, Abbott Vascular, CathWorks, Siemens, and Coroventis Research; has received research grants from Abbott Vascular, Coroventis Research, Cathworks, and Boston Scientific; and holds minor equities in Philips Volcano, Siemens, GE Healthcare, Edwards Lifesciences, HeartFlow, Opsens, Sanofi, and Celiad. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2024 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Low fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) has been associated with adverse clinical outcomes. Hitherto, this assessment has been independent of the epicardial vessel interrogated., Objectives: This study sought to assess the predictive capacity of post-PCI FFR for target vessel failure (TVF) stratified by coronary artery., Methods: We performed a systematic review and individual patient-level data meta-analysis of randomized clinical trials and observational studies with protocol-recommended post-PCI FFR assessment. The difference in post-PCI FFR between left anterior descending (LAD) and non-LAD arteries was assessed using a random-effect models meta-analysis of mean differences. TVF was defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target vessel revascularization., Results: Overall, 3,336 vessels (n = 2,760 patients) with post-PCI FFR measurements were included in 9 studies. The weighted mean post-PCI FFR was 0.89 (95% CI: 0.87-0.90) and differed significantly between coronary vessels (LAD = 0.86; 95% CI: 0.85 to 0.88 vs non-LAD = 0.93; 95% CI: 0.91-0.94; P < 0.001). Post-PCI FFR was an independent predictor of TVF, with its risk increasing by 52% for every reduction of 0.10 FFR units, and this was mainly driven by TVR. The predictive capacity for TVF was poor for LAD arteries (AUC: 0.52; 95% CI: 0.47-0.58) and moderate for non-LAD arteries (AUC: 0.66; 95% CI: 0.59-0.73; LAD vs non-LAD arteries, P = 0.005)., Conclusions: The LAD is associated with a lower post-PCI FFR than non-LAD arteries, emphasizing the importance of interpreting post-PCI FFR on a vessel-specific basis. Although a higher post-PCI FFR was associated with improved prognosis, its predictive capacity for events differs between the LAD and non-LAD arteries, being poor in the LAD and moderate in the non-LAD vessels., Competing Interests: Funding Support and Author Disclosures Dr Collet received research grants from Biosensors, HeartFlow Inc, Abbott Vascular, Insight Lifetech, GE Healthcare, Siemens and Shockwave Medical. Dr Johnson has received internal funding from the Weatherhead PET Center for Preventing and Reversing Atherosclerosis; has received significant institutional research support from St. Jude Medical (CONTRAST, NCT02184117) and Philips Volcano (DEFINE-FLOW, NCT02328820) for studies using intracoronary pressure and flow sensors; has an institutional licensing agreement with Boston Scientific for the smart-minimum FFR algorithm commercialized under 510(k) K191008; and has pending patents on diagnostic methods for quantifying aortic stenosis and TAVI physiology and also algorithms to correct pressure tracings from fluid-filled catheters. Dr Mizukami has received consultancy fees from Zeon Medical. Dr Fearon receives institutional research support from Abbott Vascular, Boston Scientific, Medtronic, and Edwards Lifesciences; he has a consulting relationship with CathWorks and Siemens; and he owns minor stock options in HeartFlow. Dr Berry receives research funding from the British Heart Foundation grant (RE/18/6134217); and is employed by the University of Glasgow, which holds consultancy and research agreements for his work with Abbott Vascular, AstraZeneca, Boehringer Ingelheim, Causeway Therapeutics, Coroventis, Genentech, GlaxoSmithKline, HeartFlow, Menarini, Neovasc, Siemens Healthcare, and Valo Health. Dr Sonck is supported by a grant provided by the CardioPath PhD program. Dr Collison has received honoraria/speaker fees from Abbott. Dr Koo has received an institutional research grant from St. Jude Medical (Abbott Vascular) and Philips Volcano. Dr Meneveau has received consultancy and speaker fees from Abbott Vascular, Edwards Lifesciences, Terumo, Boston Scientific, Bayer Healthcare, BMS-Pfizer, Boehringer, and AstraZeneca. Dr Oldroyd is an employee of Biosensors International. Dr Leipsic is a consultant for and holds stock options in Circle CVI and HeartFlow; and has a research grant from GE Healthcare. Dr Taylor is an employee of HeartFlow Inc. Dr Ko has received consultancy fees from Abbott Vascular and Medtronic; and has received research support from Canon Medical. Dr Perera has received research grant support from Abbott Vascular, HeartFlow, and Philips. Dr Leone received consultant fees and honoraria for lectures in sponsored symposia with Abbott Vascular and Bracco Imaging/ACIST Medical. Dr Matsuo has received consultancy fees from Zeon Medical; and has received speaker fees from Abbott Vascular Japan, Philips, and Boston Scientific. Dr Amabile reports consulting/proctoring fees from Abbott Vascular, Boston Scientific, and Shockwave Medical; and has received an institutional research grant from Abbott Vascular and Boston Scientific. Dr Piróth has received consultancy and speaker fees from Abbott Vascular, Opsens, and Boston Scientific. Dr Toth has received consultancy fees and research support from Abbott, Biotronik, Medtronic, and Terumo. Dr Ihdayhid reports receiving consulting honorarium from Abbott Medical, Edwards Lifesciences, Boston Scientific, Artrya Pty Ltd (including equity interest). Dr West is an employee of Abbott Vascular. Dr Munhoz is supported with a PhD grant from CardioPath. Dr Barbato has received speaker fees from Abbott and Boston Scientific. Dr Engstrøm has received consultancy and speaker fees from Abbott Vascular, Novo Nordisk, and Bayer AS. Dr Escaned is supported by the Intensification of Research Activity project INT22/00088 from Spanish Instituto de Salud Carlos III, and served as speaker and advisory board member for Abbott and Philips. Dr Ali has received institutional grant support Abbott, Abiomed, ACIST Medical, Amgen, Boston Scientific, Cathworks, Canon, Conavi, Heartflow, Inari, Medtronic Inc, National Institute of Health, Nipro, Opsens Medical, Medis, Philips, Shockwave, Siemens, Spectrawave, Teleflex; and consulting fees from Abiomed, AstraZeneca, Boston Scientific, Cathworks, Opsens, Philips, Shockwave and equity in Elucid, Lifelink, Spectrawave, Shockwave, VitalConnect. Dr Kern has received speaker fees from Abbott, ACIST Medical, Boston Scientific, Opsens, and Philips. Dr Pijls has received research grants from Abbott and Hexacath and consultancy fees from Abbott, GE, Philips, and HeartFlow and have equity in GE, Philips, and Heartflow. Dr De Bruyne has received institutional consulting fees from Abbott Vascular, Boston Scientific, Siemens, and GE; has received institutional grant support from Abbott Vascular, Boston Scientific, Biotronic, CathWorks, Pie Medical, and HeartFlow; and holds minor equities in Philips, Siemens, GE, Bayer, HeartFlow, Edwards Lifesciences, and Ceyliad. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Despite treatment with primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), the risk of heart failure and late death remains high. Microvascular dysfunction, as assessed by the index of microcirculatory resistance (IMR), after primary PCI for STEMI has been associated with worse outcomes. It is unclear whether IMR after primary PCI predicts cardiac death., Objectives: The aims of this analysis were: 1) to determine if IMR is an independent predictor of cardiac death; 2) to assess the optimal cutoff value of IMR after STEMI; and 3) to compare IMR with several cardiac magnetic resonance parameters, including infarct size., Methods: In a collaborative, pooled analysis of individual patient data from 6 cohorts that measured IMR directly after primary PCI, cardiac mortality up to 5 years was estimated using Kaplan-Meier analyses. The primary endpoint was cardiac death using the predefined IMR cutoff value of 40., Results: In total, 1,265 patients were included in this study with a median follow-up of 2.8 years (IQR: 1.2-5.0 years). Cardiac death at 5 years occurred in 2.2% and 4.9% of patients (HR: 2.81; 95% CI: 1.34-5.88; P = 0.006) in the IMR ≤40 and IMR >40 groups, respectively. The composite of cardiac death or hospitalization for heart failure occurred in 4.9% and 8.9% (HR: 1.98; 95% CI: 1.20-3.29; P = 0.008) in the IMR ≤40 and IMR >40 groups, respectively. IMR was an independent predictor of cardiac death, whereas coronary flow reserve was not. The optimal cutoff value of IMR for the prediction of cardiac death in this cohort was 70 (HR: 4.73; 95% CI: 2.27-9.83; P < 0.001). Infarct size was 17.6% ± 13.3% and 23.9% ± 14.6% of the left ventricular mass in the IMR ≤40 and IMR >40 groups, respectively (P < 0.001). Microvascular obstruction and intramyocardial hemorrhage occurred more frequently in the IMR >40 group than in the IMR ≤40 group., Conclusions: In this large, pooled analysis of individual patient data, IMR measured directly after primary PCI in STEMI was an independent predictor of cardiac death. IMR may be used as a tool to identify patients at the time of primary PCI who are at highest risk for late cardiac mortality and who might benefit most from additional cardioprotective therapies and monitoring., Competing Interests: Funding Support and Author Disclosures Dr van Royen has received research funding from Abbott, Philips, Medtronic, and Biotronik; has served as a consultant for RainMed, Castor, and Medtronic; and has received speaker fees from Abbott and Bayer. Dr van Leeuwen has received speaker/consulting service honoraria from Terumo, Daiichi Sankyo, and Abbott; and has received research grants from AstraZeneca, Top Sector Life Sciences and Health, Terumo, Top Medical BV, and Abbott. Dr Fineschi has received speaker honoraria and consulting fees from St. Jude Medical Italia (now Abbott). Dr Pijls has received institutional research grants from Abbott and Hexacath; is a consultant for Abbott and Opsens; holds minor equity interest in Philips, ASML, HeartFlow, and GE; is a member of the Scientific Advisory Board of HeartFlow; and has patents pending on diagnostic methods for quantifying aortic valve stenosis and microvascular physiology. Dr Berry has received institutional grants/contracts from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Novartis, and Siemens Healthcare; has received consulting fees from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Menarini, and Novartis; and has received honoraria from Abbott, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, HeartFlow, Philips, and Valo Health. Dr Oldroyd has received honoraria from Abbott, Biosensors International, and Boston Scientific; has received an institutional research grant from Boston Scientific that supported the present manuscript; and is a full-time employee of Biosensors International since May 2020. Dr Fearon has received research support from Abbott, Boston Scientific, Edwards Lifesciences, and Medtronic; has consulting agreements with CathWorks and Siemens; and has equity options with HeartFlow., (Published by Elsevier Inc.)

Background: Previous studies comparing percutaneous coronary intervention (PCI) with coronary artery bypass grafting (CABG) in patients with multivessel coronary disease not involving the left main have shown significantly lower rates of death, myocardial infarction (MI), or stroke after CABG. These studies did not routinely use current-generation drug-eluting stents or fractional flow reserve (FFR) to guide PCI., Methods: FAME 3 (Fractional Flow Reserve versus Angiography for Multivessel Evaluation) is an investigator-initiated, multicenter, international, randomized trial involving patients with 3-vessel coronary artery disease (not involving the left main coronary artery) in 48 centers worldwide. Patients were randomly assigned to receive FFR-guided PCI using zotarolimus drug-eluting stents or CABG. The prespecified key secondary end point of the trial reported here is the 3-year incidence of the composite of death, MI, or stroke., Results: A total of 1500 patients were randomized to FFR-guided PCI or CABG. Follow-up was achieved in >96% of patients in both groups. There was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI compared with CABG (12.0% versus 9.2%; hazard ratio [HR], 1.3 [95% CI, 0.98-1.83]; P =0.07). The rates of death (4.1% versus 3.9%; HR, 1.0 [95% CI, 0.6-1.7]; P =0.88) and stroke (1.6% versus 2.0%; HR, 0.8 [95% CI, 0.4-1.7]; P =0.56) were not different. MI occurred more frequently after PCI (7.0% versus 4.2%; HR, 1.7 [95% CI, 1.1-2.7]; P =0.02)., Conclusions: At 3-year follow-up, there was no difference in the incidence of the composite of death, MI, or stroke after FFR-guided PCI with current-generation drug-eluting stents compared with CABG. There was a higher incidence of MI after PCI compared with CABG, with no difference in death or stroke. These results provide contemporary data to allow improved shared decision-making between physicians and patients with 3-vessel coronary artery disease., Registration: URL: https://www., Clinicaltrials: gov; Unique identifier: NCT02100722., Competing Interests: Disclosures Dr Pijls receives research funding from Abbott, has consulting relationships with Abbott and Opsens, and has stock or stock options with ASML, General Electric, HeartFlow, Hexacath, and Philips. Dr Mansour has consulting relationships with Abbott Vascular, Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Novartis, Pfizer, and Servier Affaires, and received a research grant from Opsens Inc and Abbott Vascular. Dr Kala has a consulting relationship with Boston Scientific, Medtronic, and Servier Affaires, and receives honoraria from AstraZeneca and Bayer. Dr Angeras receives research funding from Abbott Vascular and AstraZeneca and has a consulting relationship with Abbott Vascular and Boston Scientific. Dr Miner has a consulting relationship with Abbott, Amgen, Astra Zeneca, Bayer, Boehringer, Novartis, Opsens, Pfizer, and Servier Affaires Medicales. Dr Engstrøm has a consulting relationship with Abbott Vascular, Bayer, and Novo Nordisk. Dr Christiansen has a consulting relationship with Abbott Vascular and has received research grants from Abbott Vascular. Dr Tonino has received research grants from Biosensors and Opsens. Dr Reardon has a consulting relationship with Boston Scientific and W.L. Gore & Associates. Dr Otsuki has received research grants from the Uehara Memorial Foundation, Abbott, Medtronic, Boston Scientific, and Terumo. Dr Kobayashi has a consulting relationship with Abbott Vascular. Dr Hlatky has a consulting relationship with Blue Cross and Blue Shield and research support from HeartFlow. Dr Mahaffey has received research grants or contracts from the American Heart Association, Apple, Inc, Bayer, California Institute Regenerative Medicine, Eidos, Ferring, Gilead, Google (Verily), Idorsia, Johnson & Johnson, Luitpold, PAC-12, Precordior, and Sanifit; has provided consulting or other services for Amgen, Applied Therapeutics, AstraZeneca, Bayer, CSL Behring, Elsevier, FibroGen, Inova, Johnson & Johnson, Lexicon, MyoKardia, Novartis, Novo Nordisk, Otsuka, PhaseBio, Portola, Quidel, Sanofi, and Theravance; and has equity in Precordior. Dr Yeung has a consulting relationship with Medtronic. Dr De Bruyne has an institutional consulting relationship with Boston Scientific, Abbott Vascular, CathWorks, Siemens, GE Healthcare, and Coroventis Research; receives institutional research grants from Abbott Vascular, Coroventis Research, CathWorks, and Boston Scientific; and holds minor equities in Philips, Siemens, GE Healthcare, CathWorks, Edwards Life Sciences, HeartFlow, Opsens, Celyad, Xenter, Medyria, Bayer, and Sanofi. Dr Fearon receives research funding from Abbott, Medtronic, and Boston Scientific and has a consulting relationship with Siemens and CathWorks and stock options with HeartFlow. The other authors report no conflicts of interest.

Background: The functional SYNTAX score (FSS), which incorporates functional information as assessed by fractional flow reserve (FFR), is a better predictor of outcome after percutaneous coronary intervention (PCI) in patients with less complex coronary artery disease (CAD)., Objectives: This study sought to test the prognostic value of the FSS in patients with complex CAD eligible for coronary artery bypass grafting (CABG)., Methods: The FAME 3 (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation 3) trial compared FFR-guided PCI with CABG in patients with angiographic 3-vessel CAD. In this prespecified substudy, the angiographic core laboratory calculated the SYNTAX score (SS) and then the FSS by eliminating lesions that were not significant based on FFR. Outcomes in the PCI patients based on the FSS and the SS were compared to each other and to the patients treated with CABG., Results: The FSS reclassified more than one-quarter of patients from an SS >22 to an FSS ≤22. In the 50% of PCI patients who had an FSS ≤22, the primary endpoint occurred at a similar rate to patients treated with CABG (P = 0.77). The primary endpoint in patients without functionally significant 3-vessel CAD was similar to the CABG group (P = 0.97). The rate of myocardial infarction and revascularization among all deferred lesions was 0.5% and 3.2%, respectively., Conclusions: By measuring the FSS, one can identify 50% of patients who have a similar outcome at 1 year with PCI compared with CABG. Lesions deferred from PCI based on FFR have a low event rate., Competing Interests: Funding Support and Author Disclosures Dr Kobayashi serves as a consultant for Abbott Vascular. Dr Oldroyd serves as a chief medical officer for Biosensors International. Dr Reardon serves as a consultant for Medtronic, Boston Scientific, Abbott, and Gore Medical. De Bruyne has stock or stock options with Edwards LifeSciences, General Electric, HeartFlow, Philips, and Siemens. Dr Pijls has received research funding from Abbott; has consulting relationships with Abbott and Opsens; and has stock or stock options with ASML, General Electric, HeartFlow, Hexacath, and Philips. Dr Fearon has received institutional research support from Abbott Vascular, Boston Scientific, and Medtronic; has a consulting relationship with CathWorks and Siemens; and has stock options with HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Importance: Titanium-nitride-oxide (TiNO)-coated stents show faster strut coverage compared with drug-eluting stents without excessive intimal-hyperplasia observed in bare metal stents. It is important to study long-term clinical outcomes after treatment of patients with an acute coronary syndrome (ACS) by TiNO-coated stents, which are neither drug-eluting stents nor bare metal stents., Objective: To compare the rate of main composite outcome of cardiac death, myocardial infarction (MI), or ischemia-driven target lesion revascularization at 5 years in patients with ACS randomized to receive either a TiNO-coated stent or a third-generation everolimus-eluting stent (EES)., Design, Setting, and Participants: This multicenter, randomized, controlled, open-label trial was conducted in 12 clinical sites in 5 European countries and enrolled patients from January 2014 to August 2016. Patients presenting with ACS (ST-segment elevation MI, non-ST-segment elevation MI, and unstable angina) with at least 1 de novo lesion were randomized to receive either a TiNO-coated stent or an EES. The present report analyzes the long-term follow-up for the main composite outcome and its individual components. Analysis took place between November 2022 to March 2023., Main Outcome: The primary end point was a composite of cardiac death, MI, or target lesion revascularization at 12-month follow-up., Results: A total of 1491 patients with ACS were randomly assigned to receive either TiNO-coated stents (989 [66.3%]) or EES (502 [33.7%]). The mean (SD) age was 62.7 (10.8) years, and 363 (24.3%) were female. At 5 years, the main composite outcome events occurred in 111 patients (11.2%) in the TiNO group vs 60 patients (12%) in the EES group (hazard ratio [HR], 0.94; 95% CI, 0.69-1.28; P = .69). The rate of cardiac death was 0.9% (9 of 989) vs 3.0% (15 of 502) (HR, 0.30; 95% CI, 0.13-0.69; P = .005), the rate of MI was 4.6% (45 of 989) vs 7.0% (35 of 502) (HR, 0.64; 95% CI, 0.41-0.99; P = .049), the rate of stent thrombosis was 1.2% (12 of 989) vs 2.8% (14 of 502) (HR, 0.43; 95% CI, 0.20-0.93; P = .034), and the rate of target lesion revascularization was 7.4% (73 of 989) vs 6.4% (32 of 502) (HR, 1.16; 95% CI, 0.77-1.76; P = .47) in the TiNO-coated stent arm and in the EES arm, respectively., Conclusion and Relevance: In this study, patients with ACS had a main composite outcome that was not different 5 years after TiNO-coated stent or EES., Trial Registration: ClinicalTrials.gov Identifier: NCT02049229.

Background: Randomised studies of percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) have shown inconsistent outcomes, suggesting incomplete understanding of this cohort and their coronary physiology. To address this shortcoming, we designed a prospective observational study to measure the recovery of absolute coronary blood flow following successful CTO PCI Aims: We sought to identify patient and procedural characteristics associated with a favourable physiological outcome after CTO PCI., Methods: Consecutive patients with a CTO subtending viable myocardium underwent PCI utilising contemporary techniques and the hybrid algorithm. Immediately after PCI, and at 3-month follow-up, physiological measurements were performed utilising continuous thermodilution., Results: A total of 81 patients were included with a mean age of 63.6±8.9 years, and 66 (81.5%) were male. Physiological measurements of absolute coronary blood flow in the CTO vessel increased by 30% (p<0.001) and microvascular resistance reduced by 16% (p<0.001) from immediately post-CTO PCI to follow-up assessment. Fractional flow reserve increased by 0.02 (p=0.015) in the same period. Prior coronary artery bypass graft (CABG) and a higher estimated glomerular filtration rate (eGFR) were associated with a larger change in absolute flow. An extraplaque strategy was associated with a smaller change in absolute flow., Conclusions: Post-CTO PCI, there is a continued augmentation in absolute coronary blood flow and reduction in microvascular resistance from baseline to follow-up at 3 months. Prior CABG and a higher baseline eGFR were predictors of a larger change in absolute coronary flow, whilst an extraplaque final wire path strategy predicted a smaller change. Lastly, the patient characteristics and comorbidities had a larger influence than procedural factors on the observed change in absolute flow.

Background: Contemporary chronic total occlusion (CTO) percutaneous coronary intervention (PCI) incorporates wire escalation and dissection/re-entry recanalisation strategies., Aims: The purpose of the study was to investigate changes in collateral function after CTO PCI and to identify whether the mode of successful recanalisation influences collateral function regression., Methods: Patients scheduled for elective CTO PCI with evidence of viability in the CTO territory by noninvasive imaging were included in this study. After successful CTO PCI, the aortic pressure (Pa) and distal coronary artery wedge pressure (Pw) during balloon occlusion were measured, both in a resting state and during infusion of intravenous adenosine, allowing the calculation of the pressure-derived collateral pressure index at rest and hyperaemia (CPI rest and the collateral fractional flow reserve [FFR coll ], respectively). Measurements were repeated 3 months later during angiographic follow-up., Results: Eighty-one patients had physiological measurements at baseline and follow-up. In the final cohort the mean age was 64 years and 82% were male. The mean maximal stent diameter and total stent length were 3.2±0.5 mm and 68±31 mm, respectively. Successful strategies were antegrade wiring (64.2%), antegrade dissection re-entry (8.6%), and retrograde dissection re-entry (27.1%). Between the index procedure and follow-up, wedge pressure decreased from 34±11 mmHg to 21±8.5 mmHg (p<0.01), respectively. FFR coll changed from 0.34±0.11 to 0.19±0.09 (p<0.01) at follow-up and CPI rest from 0.40±0.14 to 0.17±0.09 (p<0.01). Absolute maximum collateral flow decreased from 55±32 ml/min directly after PCI to 38±24 ml/min (p<0.01). There was no relation between the recanalisation technique and changes in FFR coll ., Conclusions: There was a significant reduction in collateral flow over time, independent of the recanalisation technique.

Background: We evaluate the prognostic value of measuring fractional flow reserve (FFR) after percutaneous coronary intervention (post-PCI FFR) and intravascular imaging in patients undergoing PCI for 3-vessel coronary artery disease in the FAME 3 trial (Fractional Flow Reserve versus Angiography for Multivessel Evaluation)., Methods: The FAME 3 trial is a multicenter, international, randomized study comparing FFR-guided PCI with coronary artery bypass grafting in patients with multivessel coronary artery disease. PCI was not noninferior with respect to the primary end point of death, myocardial infarction, stroke, or repeat revascularization at 1 year. Post-PCI FFR data were acquired on a patient and vessel-related basis. Intravascular imaging guidance was tracked. The primary end point is a comparison of target vessel failure (TVF) defined as a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization at 1 year based on post-PCI FFR values. Cox regression with robust SEs was used for analysis., Results: Of the 757 patients randomized to PCI, 461 (61%) had post-PCI FFR measurement and 11.1% had intravascular imaging performed. The median post-PCI FFR was 0.89 [IQR' 0.85-0.94]. On a vessel-level, post-PCI FFR was found to be a significant predictor of TVF univariately (hazard ratio=0.67 [95% CI' 0.48-0.93] for 0.1 unit increase, P =0.0165). On a patient-level, the single lowest post-PCI FFR value was also found to be a significant predictor of TVF univariately (hazard ratio=0.65 [95% CI' 0.48-0.89] for 0.1 unit increase, P =0.0074). Post-PCI FFR was an independent predictor of TVF in multivariable analysis adjusted for key clinical parameters. Outcomes were similar between patients who had intravascular imaging guidance and those who did not., Conclusions: Post-PCI FFR measurement was a significant predictor of TVF on a vessel and patient level and an independent predictor of outcomes in a population with complex 3-vessel coronary artery disease eligible for coronary artery bypass grafting. The limited use of intravascular imaging did not affect outcomes., Registration: URL: https://www., Clinicaltrials: gov; Unique identifier: NCT02100722.

Importance: Fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) is generally considered to reflect residual disease. Yet the clinical relevance of post-PCI FFR after drug-eluting stent (DES) implantation remains unclear., Objective: To evaluate the clinical relevance of post-PCI FFR measurement after DES implantation., Data Sources: MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant published articles from inception to June 18, 2022., Study Selection: Published articles that reported post-PCI FFR after DES implantation and its association with clinical outcomes were included., Data Extraction and Synthesis: Patient-level data were collected from the corresponding authors of 17 cohorts using a standardized spreadsheet. Meta-estimates for primary and secondary outcomes were analyzed per patient and using mixed-effects Cox proportional hazard regression with registry identifiers included as a random effect. All processes followed the Preferred Reporting Items for Systematic Review and Meta-analysis of Individual Participant Data., Main Outcomes and Measures: The primary outcome was target vessel failure (TVF) at 2 years, a composite of cardiac death, target vessel myocardial infarction (TVMI), and target vessel revascularization (TVR). The secondary outcome was a composite of cardiac death or TVMI at 2 years., Results: Of 2268 articles identified, 29 studies met selection criteria. Of these, 28 articles from 17 cohorts provided data, including a total of 5277 patients with 5869 vessels who underwent FFR measurement after DES implantation. Mean (SD) age was 64.4 (10.1) years and 4141 patients (78.5%) were men. Median (IQR) post-PCI FFR was 0.89 (0.84-0.94) and 690 vessels (11.8%) had a post-PCI FFR of 0.80 or below. The cumulative incidence of TVF was 340 patients (7.2%), with cardiac death or TVMI occurring in 111 patients (2.4%) at 2 years. Lower post-PCI FFR significantly increased the risk of TVF (adjusted hazard ratio [HR] per 0.01 FFR decrease, 1.04; 95% CI, 1.02-1.05; P < .001). The risk of cardiac death or MI also increased inversely with post-PCI FFR (adjusted HR, 1.03; 95% CI, 1.00-1.07, P = .049). These associations were consistent regardless of age, sex, the presence of hypertension or diabetes, and clinical diagnosis., Conclusions and Relevance: Reduced FFR after DES implantation was common and associated with the risks of TVF and of cardiac death or TVMI. These results indicate the prognostic value of post-PCI physiologic assessment after DES implantation.

Aim: Microvascular resistance reserve (MRR) as derived from continuous intracoronary thermodilution specifically quantifies microvasculature function. As originally described, the technique necessitates reinstrumentation of the artery and manual reprogramming of the infusion pump when performing resting and hyperemic measurements. To simplify and to render this procedure operator-independent, we developed a fully automated method. The aim of the present study is to validate the automated procedure against the originally described one., Methods and Results: For the automated procedure, an infusion pump was preprogrammed to allow paired resting-hyperemic thermodilution assessment without interruption. To validate the accuracy of this new approach, 20 automated measurements were compared to those obtained in the same vessels with conventional paired resting-hyperemic thermodilution measurements (i.e., with a sensor pullback at each infusion rate and manual reprogramming of the infusion pump).  A close correlation between the conventional and the automated measuring technique was found for resting flow (Q rest : r = 0.89, mean bias = 2.52; SD = 15.47), hyperemic flow (Q hyper : r = 0.88, mean bias = -2.65; SD = 27.96), resting microvascular resistance (R μ-rest : r = 0.90, mean bias = 52.14; SD = 228.29), hyperemic microvascular resistance R μ-hyper : r = 0.92, mean bias = 12.95; SD = 57.80), and MRR (MRR: r = 0.89, mean bias = 0.04, SD = 0.59).  Procedural time was significantly shorter with the automated method (5'25″ ± 1'23″ vs. 4'36″ ± 0'33″, p = 0.013)., Conclusion: Continuous intracoronary thermodilution-derived measurements of absolute flow, absolute resistance, and MRR can be fully automated. This further shortens and simplifies the procedure when performing paired resting-hyperemic measurements., (© 2022 Wiley Periodicals LLC.)

Background: Patients with suspected non-ST-segment elevation acute coronary syndrome (NSTE-ACS) are currently transported and admitted to the nearest emergency department (ED) for risk stratification, diagnostic workup and treatment. Although such patients with NSTE-ACS can benefit from direct transfer to a PCI center for early invasive treatment, no reliable prehospital triage tools are available. Recently, the PreHEART score has been validated in the PreHEART study for prehospital triage of patients with suspected NSTE-ACS., Methods: The primary objective of the TRIAGE-ACS study, a prospective cohort study, is to determine whether prehospital triage using the PreHEART score can significantly reduce time from first medical contact to final diagnostics and revascularization in patients in need of coronary revascularization. The first cohort (control cohort; n = 500) is observatory and is used as a reference group for the second cohort. In the second cohort (interventional cohort; n = 500) patients are stratified in the ambulance for direct transfer to either a PCI or a non-PCI center, based on the PreHEART score. These two cohorts will be compared with each other. In total, 1000 patients will be included. Follow-up for endpoints will be performed by reviewing the medical record after 30 days, 1 year, and 2 years., Conclusion: The TRIAGE-ACS study is the first prospective study to investigate the impact of prehospital triage using the PreHEART score on time to final invasive diagnostics and treatment in patients with NSTE-ACS in need of revascularization by transferring high risk patients directly to a PCI center and patients at a low risk of having an NSTE-ACS to a non-PCI center. Such triage strategy could potentially result in optimization of regional care for all ACS patients., (Copyright © 2022 Elsevier Inc. All rights reserved.)

In acute myocardial infarction (AMI), myocardial reperfusion injury may undo part of the recovery after revascularization of the occluded coronary artery. Selective intracoronary hypothermia is a novel method aimed at reducing myocardial reperfusion injury, but its presumed protective effects in AMI still await further elucidation. This proof-of-concept study assesses the potential protective effects of selective intracoronary hypothermia in an ex-vivo , isolated beating heart model of AMI. In four isolated Langendorff perfused beating pig hearts, an anterior wall myocardial infarction was created by inflating a balloon in the mid segment of the left anterior descending (LAD) artery. After one hour, two hearts were treated with selective intracoronary hypothermia followed by normal reperfusion (cooled hearts). In the other two hearts, the balloon was deflated after one hour, allowing normal reperfusion (control hearts). Biopsies for histologic and electron microscopic evaluation were taken from the myocardium at risk at different time points: before occlusion (t = BO); 5 minutes before reperfusion (t = BR); and 10 minutes after reperfusion (t = AR). Electron microscopic analysis was performed to evaluate the condition of the mitochondria. Histological analyses included evaluation of sarcomeric collapse and intramyocardial hematoma. Electron microscopic analysis revealed intact mitochondria in the hypothermia treated hearts compared to the control hearts where mitochondria were more frequently damaged. No differences in the prespecified histological parameters were observed between cooled and control hearts at t = AR. In the isolated beating porcine heart model of AMI, reperfusion was associated with additional myocardial injury beyond ischemic injury. Selective intracoronary hypothermia preserved mitochondrial integrity compared to nontreated controls.

Background: Previous studies have shown that quality of life improves after coronary revascularization more so after coronary artery bypass grafting (CABG) than after percutaneous coronary intervention (PCI). This study aimed to evaluate the effect of fractional flow reserve guidance and current generation, zotarolimus drug-eluting stents on quality of life after PCI compared with CABG., Methods: The FAME 3 trial (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) is a multicenter, international trial including 1500 patients with 3-vessel coronary artery disease who were randomly assigned to either CABG or fractional flow reserve-guided PCI. Quality of life was measured using the European Quality of Life-5 Dimensions (EQ-5D) questionnaire at baseline and 1 and 12 months. The Canadian Cardiovascular Class angina grade and working status were assessed at the same time points and at 6 months. The primary objective was to compare EQ-5D summary index at 12 months. Secondary end points included angina grade and work status., Results: The EQ-5D summary index at 12 months did not differ between the PCI and CABG groups (difference, 0.001 [95% CI, -0.016 to 0.017]; P =0.946). The trajectory of EQ-5D during the 12 months differed ( P <0.001) between PCI and CABG: at 1 month, EQ-5D was 0.063 (95% CI, 0.047 to 0.079) higher in the PCI group. A similar trajectory was found for the EQ (EuroQol) visual analogue scale. The proportion of patients with Canadian Cardiovascular Class 2 or greater angina at 12 months was 6.2% versus 3.1% (odds ratio, 2.5 [95% CI, 0.96-6.8]), respectively, in the PCI group compared with the CABG group. A greater percentage of younger patients (<65 years old) were working at 12 months in the PCI group compared with the CABG group (68% versus 57%; odds ratio, 3.9 [95% CI, 1.7-8.8])., Conclusions: In the FAME 3 trial, quality of life after fractional flow reserve-guided PCI with current generation drug-eluting stents compared with CABG was similar at 1 year. The rate of significant angina was low in both groups and not significantly different. The trajectory of improvement in quality of life was significantly better after PCI, as was working status in those <65 years old., Registration: URL: https://www., Clinicaltrials: gov; Unique identifier: NCT02100722.

The timely revascularization of an occluded coronary artery is the cornerstone of treatment in patients with ST-elevation myocardial infarction (STEMI). As essential as this treatment is, it can also cause additional damage to cardiomyocytes that were still viable before reperfusion, increasing infarct size. This has been termed "myocardial reperfusion injury". To date, there is still no effective treatment for myocardial reperfusion injury in patients with STEMI. While numerous attempts have been made to overcome this hurdle with various experimental therapies, the common denominator of these therapies is that, although they often work in the preclinical setting, they fail to demonstrate the same results in human trials. Hypothermia is an example of such a therapy. Although promising results were derived from experimental studies, multiple randomized controlled trials failed to do the same. This review includes a discussion of hypothermia as a potential treatment for myocardial reperfusion injury, including lessons learned from previous (negative) trials, advanced techniques and materials in current hypothermic treatment, and the possible future of hypothermia for cardioprotection in patients with STEMI.

Aims: We evaluated the long-term prognostic value of invasively assessing coronary physiology after heart transplantation in a large multicentre registry., Methods and Results: Comprehensive intracoronary physiology assessment measuring fractional flow reserve (FFR), the index of microcirculatory resistance (IMR), and coronary flow reserve (CFR) was performed in 254 patients at baseline (a median of 7.2 weeks) and in 240 patients at 1 year after transplantation (199 patients had both baseline and 1-year measurement). Patients were classified into those with normal physiology, reduced FFR (FFR ≤ 0.80), and microvascular dysfunction (either IMR ≥ 25 or CFR ≤ 2.0 with FFR > 0.80). The primary outcome was the composite of death or re-transplantation at 10 years. At baseline, 5.5% had reduced FFR; 36.6% had microvascular dysfunction. Baseline reduced FFR [adjusted hazard ratio (aHR) 2.33, 95% confidence interval (CI) 0.88-6.15; P = 0.088] and microvascular dysfunction (aHR 0.88, 95% CI 0.44-1.79; P = 0.73) were not predictors of death and re-transplantation at 10 years. At 1 year, 5.0% had reduced FFR; 23.8% had microvascular dysfunction. One-year reduced FFR (aHR 2.98, 95% CI 1.13-7.87; P = 0.028) and microvascular dysfunction (aHR 2.33, 95% CI 1.19-4.59; P = 0.015) were associated with significantly increased risk of death or re-transplantation at 10 years. Invasive measures of coronary physiology improved the prognostic performance of clinical variables (χ2 improvement: 7.41, P = 0.006). However, intravascular ultrasound-derived changes in maximal intimal thickness were not predictive of outcomes., Conclusion: Abnormal coronary physiology 1 year after heart transplantation was common and was a significant predictor of death or re-transplantation at 10 years., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Background: Single-center data suggest that the index of microcirculatory resistance (IMR) measured early after heart transplantation predicts subsequent acute rejection., Objectives: The goal of this study was to validate whether IMR measured early after transplantation can predict subsequent acute rejection and long-term outcome in a large multicenter cohort., Methods: From 5 international cohorts, 237 patients who underwent IMR measurement early after transplantation were enrolled. The primary outcome was acute allograft rejection (AAR) within 1 year after transplantation. A key secondary outcome was major adverse cardiac events (MACE) (the composite of death, re-transplantation, myocardial infarction, stroke, graft dysfunction, and readmission) at 10 years., Results: IMR was measured at a median of 7 weeks (interquartile range: 3-10 weeks) post-transplantation. At 1 year, the incidence of AAR was 14.4%. IMR was associated proportionally with the risk of AAR (per increase of 1-U IMR; adjusted hazard ratio [aHR]: 1.04; 95% confidence interval [CI]: 1.02-1.06; p < 0.001). The incidence of AAR in patients with an IMR ≥18 was 23.8%, whereas the incidence of AAR in those with an IMR <18 was 6.3% (aHR: 3.93; 95% CI: 1.77-8.73; P = 0.001). At 10 years, MACE occurred in 86 (36.3%) patients. IMR was significantly associated with the risk of MACE (per increase of 1-U IMR; aHR: 1.02; 95% CI: 1.01-1.04; P = 0.005)., Conclusions: IMR measured early after heart transplantation is associated with subsequent AAR at 1 year and clinical events at 10 years. Early IMR measurement after transplantation identifies patients at higher risk and may guide personalized posttransplantation management., Competing Interests: Funding Support and Author Disclosures Dr Angerås has received research grant, speaker fees, and personal fees from Abbott Vascular. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Published by Elsevier Inc.)

The need for a quantitative and operator-independent assessment of coronary microvascular function is increasingly recognized. We propose the theoretical framework of microvascular resistance reserve (MRR) as an index specific for the microvasculature, independent of autoregulation and myocardial mass, and based on operator-independent measurements of absolute values of coronary flow and pressure. In its general form, MRR equals coronary flow reserve (CFR) divided by fractional flow reserve (FFR) corrected for driving pressures. In 30 arteries, pressure, temperature, and flow velocity measurements were obtained simultaneously at baseline (BL), during infusion of saline at 10 mL/min (rest) and 20 mL/min (hyperemia). A strong correlation was found between continuous thermodilution-derived MRR and Doppler MRR (r = 0.88; 95% confidence interval: 0.72-0.93; P < 0.001). MRR was independent from the epicardial resistance, the lower the FFR value, the greater the difference between MRR and CFR. Therefore, MRR is proposed as a specific, quantitative, and operator-independent metric to quantify coronary microvascular dysfunction., Competing Interests: Funding Support and Author Disclosures Dr De Bruyne has had a consulting relationship with Boston Scientific, Abbott Vascular, CathWorks, Siemens, and Coroventis Research; has received research grants from Abbott Vascular, Coroventis Research, Cathworks, and Boston Scientific; and holds minor equities in Philips-Volcano, Siemens, GE Healthcare, Edwards Life Sciences, HeartFlow, Opsens, and Celiad. Dr Pijls has received institutional grants from Abbott Vascular and Hexacath; has served as a consultant for Abbott Vascular, GE, and Opsens; and has minor equities in Philips, GE, ASML, and HeartFlow. Dr Collet has received research grants from Biosensor, GE Healthcare, Medis Medical Imaging, Pie Medical Imaging, Cathworks, Boston Scientific, Siemens, HeartFlow Inc, and Abbott Vascular; and has received consultancy fees from Heart Flow Inc, Opsens, Pie Medical Imaging, Abbott Vascular, and Philips-Volcano. Dr Barbato has received speaker’s fees from Abbott Vascular, Boston Scientific, and GE. Dr Fearon has received institutional research support from Abbott Vascular, Medtronic, and Edwards Lifesciences; has had a consulting relationship with CathWorks; and holds minor stock options with HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021. Published by Elsevier Inc.)

Background: Quantification of microvascular function requires the measurement of flow and resistance at rest and during hyperaemia. Continuous intracoronary thermodilution accurately measures coronary flow during hyperaemia., Aims: The aim of this study was to investigate whether continuous coronary thermodilution using lower infusion rates also enables volumetric coronary blood flow measurements (in mL/min) at rest., Methods: In 59 patients (88 arteries), the ratio of distal to proximal coronary pressure (Pd/Pa), as well as absolute blood flow (in mL/min) by continuous thermodilution, was recorded using a pressure/temperature guidewire. Saline was infused at rates of 10 and 20 mL/min. In 27 arteries, Doppler average peak velocity (APV) was measured simultaneously. Pd/Pa, APV, thermodilution-derived coronary flow reserve (CFRthermo) and coronary flow velocity reserve (CFVR) were assessed. In 10 arteries, simultaneous recordings were obtained at saline infusion rates of 6, 8, 10 and 20 mL/min., Results: Compared to baseline, saline infusion at 10 mL/min did not change Pd/Pa (0.95±0.05 versus 0.94±0.05, p=0.49) or APV (22±8 versus 23±8 cm/s, p=0.60); conversely, an infusion rate of 20 mL/min induced a decrease in Pd/Pa and an increase in APV. Stable thermodilution tracings were obtained during saline infusion at 8 and 10 mL/min, but not at 6 mL/min. Mean values of CFRthermo and CFVR were similar (2.78±0.91 versus 2.76±1.06, p=0.935) and their individual values correlated closely (r=0.89, 95% CI: 0.78-0.95, p<0.001)., Conclusions: In addition to hyperaemic flow, continuous thermodilution can quantify absolute resting coronary blood flow; therefore, it can be used to calculate coronary flow reserve and microvascular resistance reserve.

Objectives: The aim of this study was to determine the safety of selective intracoronary hypothermia during primary percutaneous coronary intervention (PPCI) in patients with anterior ST-segment elevation myocardial infarction (STEMI)., Background: Selective intracoronary hypothermia is a novel treatment designed to reduce myocardial reperfusion injury and is currently being investigated in the ongoing randomized controlled EURO-ICE (European Intracoronary Cooling Evaluation in Patients With ST-Elevation Myocardial Infarction) trial (NCT03447834). Data on the safety of such a procedure during PPCI are still limited., Methods: The first 50 patients with anterior STEMI treated with selective intracoronary hypothermia during PPCI were included in this analysis and compared for safety with the first 50 patients randomized to the control group undergoing standard PPCI. In-hospital mortality, occurrence of rhythm or conduction disturbances, stent thrombosis, onset of heart failure during the procedure, and subsequent hospital admission were assessed., Results: In-hospital mortality was 0%. One patient in both groups developed cardiogenic shock. Atrial fibrillation occurred in 0 and 3 patients (P = 0.24), and ventricular fibrillation occurred in 5 and 3 patients (P = 0.72) in the intracoronary hypothermia group and control group, respectively. Stent thrombosis occurred in 2 patients in the intracoronary hypothermia group; 1 instance was intraprocedural, and the other occurred following interruption of dual-antiplatelet therapy consequent to an intracranial hemorrhage 6 days after enrollment. No stent thrombosis was observed in the control group (P = 0.50)., Conclusions: Selective intracoronary hypothermia during PPCI in patients with anterior STEMI can be implemented within the routine of PPCI and seems to be safe. The final safety results will be reported at the end of the trial., Competing Interests: Funding Support and Author Disclosures Dr Engstrøm has received personal fees from Abbott and Bayer, outside the submitted work. Dr Oldroyd has received employee fees from Biosensors International, outside the submitted work. Dr Karamasis has received personal fees from Abbott Vascular, outside the submitted work. Dr Keeble has received grants from Abbott Vascular, Zoll, and AstraZeneca, outside the submitted work. Dr De Bruyne has received grant support from Abbott, Boston Scientific, Biotronik, and St. Jude Medical; has received consulting fees from St. Jude Medical, Opsens, and Boston Scientific, outside the submitted work; and is a shareholder in Siemens, GE, Bayer, Philips, HeartFlow, Edwards Lifesciences, and Ceyliad. Dr Berry has received grants from Abbott Vascular, AstraZeneca, Boehringer Ingelheim, Coroventis, GlaxoSmithKline, HeartFlow, Medyria, Neovasc, Novartis, Siemens Healthcare, and Menarini, outside the submitted work; and is supported by research funding from the British Heart Foundation (RE/18/6134217). Dr Pijls has received personal fees from Abbott and Opsens; holds equity in Philips, ASML, HeartFlow and GE Healthcare; and has received institutional research grants from Abbott and Hexacath. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Primary percutaneous coronary intervention (PPCI) has dramatically changed the outcome of patients with ST-elevation myocardial infarction (STEMI). However, despite improvements in interventional technology, registry data show little recent change in the prognosis of patients who survive STEMI, with a significant incidence of cardiogenic shock, heart failure, and cardiac death. Despite a technically successful PPCI procedure, a variable proportion of patients experience suboptimal myocardial reperfusion. Large infarct size and coronary microvascular injury, as the consequence of ischaemia-reperfusion injury and distal embolization of atherothrombotic debris, account for suboptimal long-term prognosis of STEMI patients. In order to address this unmet therapeutic need, a broad-range of device-based treatments has been developed. These device-based therapies can be categorized according to the pathophysiological pathways they target: (i) techniques to prevent distal atherothrombotic embolization, (ii) techniques to prevent or mitigate ischaemia/reperfusion injury, and (iii) techniques to enhance coronary microvascular function/integrity. This review is an overview of these novel technologies with a focus on their pathophysiological background, procedural details, available evidence, and with a critical perspective about their potential future implementation in the clinical care of STEMI patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Myocardial reperfusion injury-triggered by an inevitable inflammatory response after reperfusion-may undo a considerable part of the myocardial salvage achieved through timely percutaneous coronary intervention in patients with acute myocardial infarction. Because infarct size is strongly correlated to mortality and risk of heart failure, the importance of endeavors for cardioprotective therapies to attenuate myocardial reperfusion injury and decrease infarct size remains undisputed. Myocardial reperfusion injury is the result of several complex nonlinear phenomena, and for a therapy to be effective, it should act on multiple targets involved in this injury. In this regard, hypothermia remains a promising treatment despite a number of negative randomized controlled trials in humans with acute myocardial infarction so far. To turn the tide for hypothermia in patients with acute myocardial infarction, sophisticated solutions for important limitations of systemic hypothermia should continue to be developed. In this review, we provide a comprehensive overview of the pathophysiology and clinical expression of myocardial reperfusion injury and discuss the current status and possible future of hypothermia for cardioprotection in patients with acute myocardial infarction.