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Background Conduction disturbances represent one of the most common complications following transcatheter aortic valve replacement (TAVR). We sought to investigate the role of left ventricular outflow tract (LVOT) morphology in the development of conduction disturbances following TAVR. Methods and Results Consecutive patients who underwent TAVR in our center were included. The ratio between the LVOT area and the aortic annulus area was calculated. Patients were then divided into 2 groups on the basis of this ratio: group 1, which included patients with an LVOT area/aortic annulus area ratio

Abstract To evaluate the differential associations of high-risk plaque characteristics (HRPC) with resting or hyperemic physiologic indexes (instantaneous wave-free ratio [iFR] or fractional flow reserve [FFR]), a total of 214 vessels from 127 patients with stable angina or acute coronary syndrome who underwent coronary computed tomography angiography (CCTA) and invasive physiologic assessment were investigated. HPRC were classified into quantitative (minimal luminal area 0.80 or iFR > 0.89, respectively. FFR was independently associated with both quantitative and qualitative HRPC, but iFR was only associated with quantitative HRPC. Both FFR and iFR were significantly associated with the presence of ≥ 3 HRPC, and FFR demonstrated higher discrimination ability than iFR (AUC 0.703 vs. 0.648, P = 0.045), which was predominantly driven by greater discriminating ability of FFR for quantitative HRPC (AUC 0.832 vs. 0.744, P = 0.005). In conclusion, both FFR and iFR were significantly associated with CCTA-derived HRPC. Compared with iFR, however, FFR was independently associated with the presence of qualitative HRPC and showed a higher predictive ability for the presence of ≥ 3 HRPC.

RESUMEN Introducción y objetivos: La embolia coronaria de origen sistémico representa uno de los mecanismos de infarto agudo de miocardio de causa no aterosclerótica. Sin embargo, el perfil epidemiológico, clínico y angiográfico de esta entidad no ha sido aún bien definido. Nuestro objetivo fue describir las características clínicas y angiográficas y el pronóstico de los síndromes coronarios agudos (SCA) de origen embólico (SCA-E), compararlos con aquellos debidos a aterosclerosis (SCA-A) e identificar predictores clínicos de SCA-E. Métodos: Todos los pacientes con SCA atendidos en un hospital terciario entre 2003 y 2018 se clasificaron en SCA-E (n = 40) o SCA-A (n = 4.989) e incluidos de forma prospectiva en un registro multipropósito. Resultados: Entre los pacientes con SCA-E existía mayor proporción de jóvenes (27,5 frente a 9,6% tenían menos de 45 años, p

ABSTRACT Introduction and objectives: Systemic coronary artery embolism is one of the mechanisms of acute myocardial infarction of nonatherosclerotic origin. However, the epidemiological, clinical, and angiographic profile of this entity has not been properly established yet. Our objective was to describe the clinical characteristics, angiographic features, and prognosis of acute coronary syndromes (ACS) due to systemic embolism (ACS-E), compare them to those due to coronary atherosclerosis (ACS-A), and identify predictive clinical factors of ACS-E. Methods: All consecutive patients with ACS—admitted to a tertiary hospital from 2003 through 2018—were classified as ACS-E (n = 40) or ACS-A (n = 4989), and prospectively recruited on a multipurpose database. Results: Patients with ACS-E were younger (27.5% vs 9.6% were < 45 years old, P < .001), more often women (42.5% vs 22.5%, P = .003), and had higher rates of atrial fibrillation (AF) (40.0% vs 5.3%, P < .001), previous stroke (15.0% vs 3.6%, P < .001), active neoplasms (17.5% vs 6.9%, P =.009), and previous valvular surgery (12.5% vs 0.5%, P < .001). Also, a higher proportion of them were on warfarin (27.5% vs 2.9%, P < .001). The most frequent culprit vessel was the left anterior descending coronary artery in both groups. A percutaneous coronary intervention was attempted in all patients with ACS-A, and in 75.0% of those with ACS-E (P < .001) being successful in 99.1% and 80.0%, respectively. The in-hospital all-cause mortality rate was 15.0% regarding ACS-E, and 4.0% in the control group (P < .001). A multivariate analysis was performed to study the independent predictors of ACS-E, identify AF, previous valvular surgery, and active neoplasms, younger age, and female sex. Conclusions: ACS-E and ACS-A have different clinical and angiographic characteristics. Atrial fibrillation, previous valvular surgery, active neoplasms, younger age, and female sex were all independent predictors of ACS-E.

RESUMEN Introducción y objetivos: La seguridad de la revascularización fisiológica en pacientes diabéticos ha sido poco investigada. El objetivo fue determinar la seguridad de diferir la revascularización basándose en la reserva fraccional de flujo (FFR) o en el índice instantáneo libre de ondas (iFR) en pacientes con diabetes mellitus. Métodos: Análisis retrospectivo, unicéntrico, de pacientes con estenosis coronarias intermedias en quienes se había diferido la revascularización en función de unos valores de FFR > 0,80 o de iFR > 0,89. Se analizó la incidencia a largo plazo de eventos cardiovasculares adversos mayores, una combinación de muerte por cualquier causa, infarto miocárdico y revascularización del vaso diana (RVD) en pacientes con y sin diabetes. También se evaluó la incidencia de RVD según el tipo de índice fisiológico utilizado para diferir la revascularización. Resultados: Se evaluaron 164 pacientes diabéticos (214 vasos) y 280 pacientes no diabéticos (379 vasos), con una mediana de seguimiento de 43 meses. No se observaron diferencias significativas en los eventos cardiovasculares adversos mayores entre pacientes con y sin diabetes mellitus (20,1 frente a 13,2%; p = 0,245). La mortalidad por cualquier causa y de causa cardiaca no fue estadísticamente diferente entre ambos grupos en el análisis ajustado (p > 0,05). Se observó una tendencia a una mayor incidencia de infarto de miocardio en los pacientes con diabetes mellitus (6,7 frente a 2,9%; p = 0,063), pero el infarto relacionado con el vaso diana fue similar en ambos grupos (p = 0,906). En general, la RVD fue similar en diabéticos y no diabéticos (4,7 frente a 4,2%; p = 0,787); sin embargo, cuando se analizó según el índice fisiológico, los diabéticos tuvieron una mayor tasa numérica de RVD cuando se utilizó la FFR en la toma de decisiones en comparación con el iFR (6,4 frente a 0,0%; p = 0,064). Conclusiones: Diferir la revascularización de estenosis intermedias en pacientes con diabetes mellitus según la FFR o el iFR es seguro en términos de RVD e infarto relacionado con el vaso diana, con una tasa de eventos en el seguimiento a largo plazo similar a la observada en pacientes sin diabetes mellitus.

ABSTRACT Introduction and objectives: The safety of physiology-based revascularization in patients with diabetes mellitus has been scarcely investigated. Our objective was to determine the safety of deferring revascularization based on the fractional flow reserve (FFR) or the instantaneous wave-free ratio (iFR) in diabetic patients. Methods: Single-center, retrospective analysis of patients with intermediate coronary stenoses in whom revascularization was deferred based on FFR > 0.80 or iFR > 0.89 values. The long-term rate of major adverse cardiovascular events, a composite of all-cause mortality, myocardial infarction, and target vessel revascularization (TVR), was assessed in diabetic and non-diabetic patients at the follow-up. The rate of TVR based on the type of physiological index used to defer the lesion was also evaluated. Results: We evaluated 164 diabetic (214 vessels) and 280 non-diabetic patients (379 vessels). No significant differences in the rate of major adverse cardiovascular events was seen between diabetic and non-diabetic patients (20.1% vs 13.2%; P = .245) at a median follow-up of 43 months. All-cause mortality and cardiac death were not statistically different between both groups in the adjusted analysis (P > .05). A trend towards a higher rate of myocardial infarction was seen in diabetic patients (6.7% vs 2.9%; P = .063). However, the rate of target vessel myocardial infarction was similar in both groups (P = .874). Overall, TVR was similar in diabetics and non-diabetics (4.7% vs 4.2%; P = .814); however, when analyzed based on the physiological index, numerically, diabetics had a higher rate of TVR when the FFR was used in the decision-making process compared to when the iFR was used (6.4% vs 0.0%; P = .064). Conclusions: Deferring the revascularization of intermediate stenoses in patients with DM based on the FFR or the iFR is safe regarding the risk of TVR or target vessel myocardial infarction, with a rate of events at the long-term follow-up similar to that seen in non-diabetic patients.

Abstract Limited data are available regarding comparative prognosis after percutaneous coronary intervention (PCI) versus deferral of revascularization in patients with intermediate stenosis with abnormal fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). From the International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713), a total of 330 patients (338 vessels) who had coronary stenosis with FFR ≤ 0.80 but CFR > 2.0 were selected for the current analysis. Patient-level clinical outcome was assessed by major adverse cardiac events (MACE) at 5 years, a composite of all-cause death, target-vessel myocardial infarction (MI), or target-vessel revascularization. Among the study population, 231 patients (233 vessels) underwent PCI and 99 patients (105 vessels) were deferred. During 5 years of follow-up, cumulative incidence of MACE was 13.0% (31 patients) without significant difference between PCI and deferred groups (12.7% vs. 14.0%, adjusted HR 1.301, 95% CI 0.611–2.769, P = 0.495). Multiple sensitivity analyses by propensity score matching and inverse probability weighting also showed no significant difference in patient-level MACE and vessel-specific MI or revascularization. In this hypothesis-generating study, there was no significant difference in clinical outcomes between PCI and deferred groups among patients with intermediate stenosis with FFR ≤ 0.80 but CFR > 2.0. Further study is needed to confirm this finding. Clinical Trial Registration: International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713; registration date: 10/01/2018).

Abstract Introduction and objectives: Recent publications suggest that bioresorbable vascular scaffolds (BVS) are associated with an excess of thrombotic complications. We present the real-world, long-term results of a series of patients who received the Absorb BVS (Abbott Vascular, United States). Methods: A total of 213 consecutive patients who received at least 1 BVS between May 2012 and December 2016 were analyzed. The main objective of the study was the rate of target vessel failure, a composite endpoint of infarction or target vessel revascularization and cardiac death. Results: Seventy-five per cent of the patients were men (mean age, 61.4 years). The most common cause for admission was non-ST-elevation myocardial infarction (53.52%). The median follow-up was 44 months [28 months], the rate of the primary endpoint was 6.57% for the first 24 months and 7.98% at the end of the follow-up. Regarding the device, there were 6 cases (2.81%) of thrombosis (definitive, probable or possible) and 10 cases (4.69%) of restenosis. Patients with a past medical history of diabetes mellitus (HR, 1.72; 95%CI, 1.01-2.95; P = .05) and/or chronic oral anticoagulation (HR, 5.71; 95%CI, 1.12-28.94; P = .04) had a higher risk of target vessel failure. Conclusions: In this series of patients, the rate of target vessel failure was similar to the one previously described by randomized clinical trials. Events were more common during the first 2 years of follow-up and in the presence of greater cardiovascular comorbidity.

RESUMEN Introducción y objetivos: Las publicaciones sugieren que los armazones vasculares bioabsorbibles (AVB) conllevan un exceso de complicaciones trombóticas. Se describen los resultados en la vida real y a largo plazo de una serie de pacientes a los que se implantó un AVB Absorb (Abbott Vascular, EE.UU.). Métodos: Se analizaron 213 pacientes consecutivos que recibieron al menos un AVB entre mayo de 2012 y diciembre de 2016. El objetivo principal del estudio fue la incidencia de fracaso del vaso diana, un evento compuesto que incluye infarto de miocardio, revascularización del vaso diana y muerte cardiaca. Resultados: El 75% de los pacientes eran varones (edad media, 61,4 años). La causa más común de ingreso fue el infarto sin elevación del ST (53,52%). La mediana de seguimiento fue de 44 meses [28 meses]. La incidencia del evento primario fue del 6,57% durante los primeros 24 meses y del 7,98% al final del seguimiento. Respecto al dispositivo, hubo 6 casos (2,81%) de trombosis (definitiva, probable o posible) y 10 casos (4,69%) de reestenosis. Los pacientes con antecedentes de diabetes mellitus (HR = 1,72; IC95%, 1,01-2,95; p = 0,05) o con anticoagulación oral crónica (HR = 5,71; IC95%, 1,12-28,94; p = 0,04) tuvieron mayor riesgo de fracaso del vaso diana. Conclusiones: En esta serie de pacientes, la incidencia de fracaso del vaso diana fue comparable a la descrita previamente en ensayos clínicos aleatorizados. Los eventos adversos fueron más frecuentes en los primeros 2 años de seguimiento y en presencia de mayor comorbilidad cardiovascular.

Sr. Editor: Aunque la utilización de nuevos stents ha mejorado los resultados tras una angioplastia coronaria, el desarrollo de reestenosis del stent (RIS) continúa siendo uno de los principales problemas tras este tipo de intervenciones. Se define la RIS como aquella estenosis > 50% que se desarrolla en un segmento del stent o en sus bordes (hasta 5 mm), generalmente secundaria a una proliferación neointimal progresiva. Se ha descrito hasta casi en un 30% de los enfermos que han recibido un stent convencional y en un 10% de los portadores de uno farmacoactivo1-3.

To the Editor, Although the use of new stents has improved the results after coronary angioplasty, the development of in-stent restenosis (ISR) is still one of the leading problems following these interventions. ISR is defined as a stenosis > 50% developing in a segment or border of the stent (up to 5 mm). It is often due to progressive neointimal proliferation and has been reported in up to 30% of the patients with conventional stents and 10% of drug-eluting stent carriers.1-3

Thirty-six-year-old male referred to the emergency room by the general practitioner with chest pain of 1-month duration. After the initial assessment revealed the presence of diffuse T-wave flattening, normal troponin levels, and a normal echocardiogram, the patient was discharged with a diagnosis of low-risk atypical chest pain. However, due to symptom recurrence and the fact that the treadmill test triggered angina-like symptoms and the ECG showed transient T-wave abnormalities, a coronary angiography was performed that ruled out the presence of epicardial stenosis (video 1 of the supplementary data). The patient was readmitted a week later due to disabling oppressive chest pain related to low intensity exercise. Due to persistent angina without coronary stenosis, an intracoronary physiological assessment was scheduled with acetylcholine, adenosine, and simultaneous pressure and flow measurements in the left anterior descending coronary artery using a dual-sensor pressure and Doppler velocity guidewire. Acetylcholine (Ach) (200 mcg) triggered the patient’s typical symptoms, the repolarization abnormalities seen on the ECG and the 50% decrease of coronary artery flow velocity (APV) without epicardial spasm (video 2 of the supplementary data). Intracoronary nitroglycerin (NTG) solved all abnormalities (figure 1A,B). The adenosine non-endothelium-dependent assessment revealed a normal fractional flow reserve (FFR), hyperemic microcirculatory resistance (HMR), and coronary flow reserve (CFR) (figure 1C). Because of the clinical features present (acetylcholine-triggered angina with repolarization abnormalities seen on the ECG without epicardial spasm), microvascular vasospastic angina was diagnosed. Medical therapy adjustment with calcium channel blockers as first-line treatment improved the patient’s symptoms at the follow-up.

Varón de 36 años derivado a urgencias por su médico de familia con un cuadro de dolor torácico de 1 mes de evolución. La evaluación inicial en urgencias reveló la presencia de aplanamiento difuso de la onda T, niveles normales de troponina y un ecocardiograma normal, por lo que se dio de alta al paciente con un diagnóstico de dolor torácico atípico de riesgo bajo. No obstante, presentó recurrencia de los síntomas, por lo que se realizó una ergometría que resultó clínica y eléctricamente positiva. En consecuencia, se realizó una coronariografía que descartó la presencia de estenosis coronarias epicárdicas (vídeo 1 del material adicional).

Background Resistive reserve ratio is a thermodilution‐based index which integrates both coronary flow and pressure. Resistive reserve ratio represents the vasodilatory capacity of interrogated vessels including both epicardial coronary artery and microvascular circulation. We evaluated the prognostic potential of resistive reserve ratio compared with pressure‐derived index (fractional flow reserve [FFR]) or flow‐derived index (coronary flow reserve [CFR]). Methods and Results A total of 1245 patients underwent coronary pressure and flow measurement using pressure‐temperature wire. Resistive reserve ratio was calculated by CFR adjusted using the ratio between resting and hyperemic distal coronary pressure ([resting mean transit time/hyperemic mean transit time]×[resting distal coronary pressure/hyperemic distal coronary pressure]). Clinical outcome was assessed by patient‐oriented composite outcome (POCO), a composite of any death, myocardial infarction, and revascularization at 5 years. At 5 years, the cumulative incidence of POCO was significantly different according to quartiles of resistive reserve ratio (9.9%, 11.3%, 17.2%, and 22.7% in quartiles 1 to 4, respectively, log rank P0.80 or patients with CFR>2.0. (FFR>0.80 group: 14.8% versus 6.0%; log rank P=0.001; CFR>2.0 group: 13.5% versus 7.1%; log rank P=0.045). Adding resistive reserve ratio into the model for 5‐year POCO showed significantly higher global Chi square value than FFR or CFR (P

Background Sex‐specific differences may influence prognosis after deferred revascularization following fractional flow reserve (FFR) measurement. This study sought to investigate the sex differences in long‐term prognosis of patients with deferred revascularization following FFR assessment. Methods and Results A total of 879 patients (879 vessels) with deferred revascularization with FFR >0.75 who underwent FFR and coronary flow reserve measurements were enrolled from 3 countries (Korea, Japan, and Spain). Long‐term outcomes were assessed in 649 men and 230 women by the patient‐oriented composite outcome (POCO, a composite of any death, any myocardial infarction, and any revascularization). We applied inverse‐probability weighting based on propensity scores to account for differences at baseline between women and men (age, hyperlipidemia, diabetes mellitus, diameter stenosis, lesion length, multivessel disease, FFR, coronary flow reserve. The median follow‐up duration was 1855 days (745–1855 days). Median FFR values were 0.88 (0.83–0.93) in men and 0.89 (0.85–0.94) in women, respectively. The occurrences of POCO were significantly high in men compared with that in women (10.5% versus 4.2%, P=0.007). Kaplan–Meier analysis revealed that women had a significantly lower risk of POCO (χ2=7.2, P=0.007). Multivariate COX proportional hazards regression analysis revealed that age, male, diabetes mellitus, diameter stenosis, lesion length, and coronary flow reserve were independent predictors of POCO. After applying IPW, the hazard ratio of males for POCO was 2.07 (95% CI, 1.07–4.04, P=0.032). Conclusions This large multinational study reveals that long‐term outcome differs between women and men in favor of women after FFR‐guided revascularization deferral. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02186093.

Varón de 61 años portador de stent farmacoactivo (SFA) implantado hace 5 años (no hay más información disponible) que ingresa con un cuadro de infarto agudo de miocardio anterior. La coronariografía urgente reveló la presencia de una trombosis del stent muy tardía (TSMT) (figura 1A, stent indicado por flechas verdes, vídeo 1 del material adicional). Se consiguió avanzar, fácilmente, una guía Sion (Asahi Intecc) pero el catéter de tromboaspiración no consiguió cruzar la oclusión. Se optó por emplear un balón distensible de 2,5 mm que sí cruzó fácilmente la oclusión restaurando el flujo sanguíneo (figura 1B, vídeo 2 del material adicional). La ecocardiografía intravascular (IVUS) que se realizó confirmó la deformación del segmento proximal del stent (aplastamiento parcial) (figura 2A, las flechas rojas señalan los struts aplastados) y una notable infradimensión e infraexpansión del stent (diámetro medio del stent de 2,75 mm, flechas verdes, y diámetro de referencia de 4,5 mm, línea azul, figura 2B). La imagen angiográfica de realce del stent confirmó los hallazgos de la IVUS. Teniendo en cuenta la deformación del stent y la discordancia entre el stent y el tamaño del vaso, se optó por dilatar con un balón no distensible de 4 mm (20 atmósferas) e implantar un nuevo SFA de 4 mm x 28 mm con excelente resultado final (figura 3, vídeo 3 del material adicional). Se observa la presencia de posible puente intramiocárdico distal.

A 61-year-old male with a drug-eluting stent (DES) implanted 5 years ago (no further information) was admitted with anterior myocardial infarction. The emergent coronary angiography performed revealed the presence of very late stent thrombosis (VLST) (figure 1A, stent in green arrows, video 1 of the supplementary data). A Sion wire (Asahi Intecc) was easily advanced, but thromboaspiration catheter failed to cross. A 2.5 mm compliant balloon that crossed easily was used to restore the flow (figure 1B, video 2 of the supplementary data). Intravascular ultrasound (IVUS) revealed the presence of proximal stent deformation (partial crush) (figure 2A, red arrows indicating crushed struts); and significant undersizing or underexpansion (average stent diameter of 2.75 mm, green arrows and 4.5 mm reference diameter, blue line, figure 2B). Stent enhancement confirmed the IVUS findings. Given the deformation of the stent and the mismatch between the stent and the vessel size, we dilated with a 4 mm non-compliant balloon (20 atm) and implanted a new 4 mm x 28 mm DES with excellent final results (figure 3, video 3 of the supplementary data). Presence of possible distal myocardial bridging.

Varón hipertenso y exfumador de 55 años hospitalizado con signos de dolor torácico típico, bloqueo de rama izquierda y niveles normales de troponina. La angiografía reveló enfermedad coronaria de 2 vasos, circunfleja izquierda y coronaria derecha. Esta última se trató con un stent y la circunfleja izquierda mediante intervención guiada por el índice diastólico instantáneo sin ondas (iFR). Después se empleó una segunda guía convencional para dar estabilidad. La figura 1A muestra la angiografía inicial (vídeo 1 del material adicional), la ecualización de las presiones proximal y distal (figura 1B y figura 2A), la angioplastia simple con balón, la medición del gradiente de presión de enclavamiento mediante el iFR (figura 1C y figura 2D), el resultado angiográfico después de la angioplastia con balón (figura 1D), la medición del iFR después de la angioplastia con balón (figura 1E y figura 2E,F) y el resultado final (figura 1F, figura 2G,H y vídeo 1 del material adicional).

A fifty-five year-old hypertensive and former smoker male admitted with signs of typical chest pain, left bundle brunch block, and normal troponin levels. The angiography revealed 2-vessel, left circumflex and right coronary artery disease. The latter was treated with a stent and for the circumflex coronary artery an instantaneous wave-free ratio (iFR)-guided intervention was decided. Then, a second conventional guidewire was used for stabilization purposes. Figure 1A shows initial angiography (video 1 of the supplementary data), equalization of proximal and distal pressures (figure 1B and figure 2A), plain balloon angioplasty and iFR wedge pressure determination (figure 1C and figure 2D), angiographic result after balloon-angioplasty (figure 1D), iFR determination after balloon angioplasty (figure 1E and figure 2E,F), and final result (figure 1F, figure 2G,H and video 1 of the supplementary data).

Background Quantitative flow ratio (QFR), a novel functional angiography technique, computes fractional flow reserve (FFR) without pressure wires or adenosine. We investigated interindividual variations in the adenosine‐induced hemodynamics during FFR assessment and their influence on QFR diagnostic performance. Methods and Results Patients with coronary stenoses who underwent intracoronary pressure and flow assessment were analyzed. Adenosine‐induced hemodynamics during FFR measurement were determined by the percentage change in mean aortic pressure (%ΔPa) and the resistive reserve ratio (RRR). The diagnostic performance of QFR was evaluated and compared in each tertile of %ΔPa and RRR using FFR as reference. A total of 294 vessels (245 patients) were analyzed. Mean FFR was 0.80±0.11. Individuals showed a wide variation in the adenosine response in terms of %ΔPa (ranging from −75% to 43%; median, −9% [interquartile range, −3% to −17%]) and the RRR (ranging from 0.45 to 20.15; median, 3.1 [interquartile range, 2.1–4.9]). No significant differences for diagnostic efficiency of QFR were found between tertiles of %ΔPa (area under the curve for the receiver‐operating characteristic analysis, 0.950 in tertile 1, 0.929 in tertile 2, and 0.910 in tertile 3; P=0.270) or between tertiles of the RRR (area under the curve for the receiver‐operating characteristic analysis, 0.909 in tertile 1, 0.923 in tertile 2, and 0.959 in tertile 3; P=0.167). The classification agreement between QFR and FFR was not significantly modified by %ΔPa (tertile 1, 89%; tertile 2, 87%; and tertile 3, 86%; P=0.827) or by the RRR (tertile 1, 86%; tertile 2, 85%; and tertile 3, 91%; P=0.398). Conclusions Patients undergoing FFR assessment show large interindividual variations in the magnitude of adenosine‐induced hemodynamics. However, such variations do not affect the diagnostic performance of QFR in assessing the functional relevance of observed stenoses.

Background Concerns exist about reliability of pressure‐wire‐guided coronary revascularization of non‐infarct‐related arteries (non‐IRA). We investigated whether physiological assessment of non‐IRA during the subacute phase of myocardial infarction might be flawed by microcirculatory dysfunction. Methods and Results We analyzed non‐IRA that underwent fractional flow reserve, coronary flow reserve, and the index of microcirculatory resistance assessment. Microcirculation and hyperemic response were evaluated in 49 acute myocardial infarction patients (59 non‐IRA) and compared with a matched control group of 46 stable angina (SA) patients (59 vessels). Time between acute myocardial infarction to physiological interrogation was 5.9±2.4 days. Fractional flow reserve was similar in both groups (0.79±0.11 in non‐IRA versus 0.80±0.13 in SA vessels, P=0.527). Lower coronary flow reserve values were found in non‐IRA compared with SA vessels (1.77 [1.25–2.76] versus 2.44 [1.63–4.00], P=0.018), primarily driven by an increased baseline flow in non‐IRA (rest mean transit time 0.58 [0.32–0.83] versus 0.65 s [0.39–1.20], P=0.045), whereas the hyperemic flow was similar (hyperemic mean transit time 0.26 [0.20–0.42] versus 0.26 s [0.18–0.35], P=0.873). No differences were found regarding index of microcirculatory resistance (15.6 [10.4–21.8] in non‐IRA versus 16.7 [11.6–23.6] U in SA vessels, P=0.559). During adenosine infusion, the hyperemic response was similar in both groups (non‐IRA versus SA vessels) in terms of the resistive reserve ratio (3.1±2.1 versus 3.7±2.2, P=0.118). Conclusions In the subacute phase of myocardial infarction, non‐IRA show an increased baseline flow that may cause abnormal coronary flow reserve despite preserved hyperemic flow. In non‐IRA, microcirculatory resistance and adenosine‐induced hyperemic response are similar to those found in SA patients. From a physiological perspective, these findings support the use of fractional flow reserve to interrogate non‐IRA during the subacute phase of myocardial infarction.

Background Quantitative flow ratio (QFR) has a high diagnostic accuracy in assessing functional stenoses relevance, as judged by fractional flow reserve (FFR). However, its diagnostic performance has not been thoroughly evaluated using instantaneous wave‐free ratio (iFR) or coronary flow reserve as the reference standard. This study sought to evaluate the diagnostic performance of QFR using other reference standards beyond FFR. Methods and Results We analyzed 182 patients (253 vessels) with stable ischemic heart disease and 82 patients (105 nonculprit vessels) with acute myocardial infarction in whom coronary stenoses were assessed with FFR, iFR, and coronary flow reserve. Contrast QFR analysis of interrogated vessels was performed in blinded fashion by a core laboratory, and its diagnostic performance was evaluated with respect to the other invasive physiological indices. Mean percentage diameter stenosis, FFR, iFR, coronary flow reserve, and QFR were 53.1±19.0%, 0.80±0.13, 0.88±0.12, 3.14±1.30, and 0.81±0.14, respectively. QFR showed higher correlation (r=0.863 with FFR versus 0.740 with iFR, P0.05, overall comparison P=0.061). Conclusions QFR has a high correlation and agreement with respect to both FFR and iFR, although it is better when FFR is used as the comparator. As a pressure‐derived index not depending on wire or adenosine, QFR might be a promising tool for improving the adoption rate of physiology‐based revascularization in clinical practice.

Background Bolus thermodilution and intravenous adenosine are established methods for coronary microcirculatory assessment. Yet, its adoption remains low, partly due to procedural time and patient discomfort associated with intravenous adenosine. We investigated differences between intracoronary and intravenous adenosine using bolus thermodilution in terms of microcirculatory indices, procedural time, and side effects associated with adenosine in patients with myocardial ischemia and nonobstructive coronary arteries. Methods and Results In this prospective, observational study, 102 patients with suspected myocardial ischemia and nonobstructive coronary arteries underwent measurements of mean transit time, coronary flow reserve, index of microcirculatory resistance, procedure time and patient tolerability with low‐dose intracoronary adenosine, high‐dose intracoronary adenosine (HDIC), and intravenous adenosine. HDIC induced greater hyperemia compared with low‐dose intracoronary IC adenosine and intravenous adenosine with a shorter hyperemic mean transit time, P