Randomized Trial of Anticoagulation Strategies for Noncritically Ill Patients Hospitalized With COVID-19.

BACKGROUND: Prior studies of therapeutic-dose anticoagulation in patients with COVID-19 have reported conflicting results. OBJECTIVES: We sought to determine the safety and effectiveness of therapeutic-dose anticoagulation in noncritically ill patients with COVID-19. METHODS: Patients hospitalized with COVID-19 not requiring intensive care unit treatment were randomized to prophylactic-dose enoxaparin, therapeutic-dose enoxaparin, or therapeutic-dose apixaban. The primary outcome was the 30-day composite of all-cause mortality, requirement for intensive care unit-level of care, systemic thromboembolism, or ischemic stroke assessed in the combined therapeutic-dose groups compared with the prophylactic-dose group. RESULTS: Between August 26, 2020, and September 19, 2022, 3,398 noncritically ill patients hospitalized with COVID-19 were randomized to prophylactic-dose enoxaparin (n = 1,141), therapeutic-dose enoxaparin (n = 1,136), or therapeutic-dose apixaban (n = 1,121) at 76 centers in 10 countries. The 30-day primary outcome occurred in 13.2% of patients in the prophylactic-dose group and 11.3% of patients in the combined therapeutic-dose groups (HR: 0.85; 95% CI: 0.69-1.04; P = 0.11). All-cause mortality occurred in 7.0% of patients treated with prophylactic-dose enoxaparin and 4.9% of patients treated with therapeutic-dose anticoagulation (HR: 0.70; 95% CI: 0.52-0.93; P = 0.01), and intubation was required in 8.4% vs 6.4% of patients, respectively (HR: 0.75; 95% CI: 0.58-0.98; P = 0.03). Results were similar in the 2 therapeutic-dose groups, and major bleeding in all 3 groups was infrequent. CONCLUSIONS: Among noncritically ill patients hospitalized with COVID-19, the 30-day primary composite outcome was not significantly reduced with therapeutic-dose anticoagulation compared with prophylactic-dose anticoagulation. However, fewer patients who were treated with therapeutic-dose anticoagulation required intubation and fewer died (FREEDOM COVID [FREEDOM COVID Anticoagulation Strategy]; NCT04512079).

Association of Diabetes Mellitus and Its Types with In-Hospital Management and Outcomes of Patients with Acute Myocardial Infarction.

BACKGROUND: Diabetes mellitus (DM) is an important risk factor for adverse outcomes following acute myocardial infarction (AMI), but large-scale studies investigating the differential impact of Type 1 DM (T1DM) and Type 2 DM (T2DM) on AMI outcomes are lacking. METHODS: All adult discharges for AMI in the National Inpatient Sample (October 2015 to December 2018) were included and stratified into T1DM, T2DM and non-DM (NDM) groups. Outcomes of interests were all-cause mortality, major adverse cardiovascular and cerebrovascular events (MACCE), major bleeding and acute ischemic stroke, as well as invasive management. Binomial hierarchical multilevel multivariable logistic regression with adjusted odds ratios (aOR) and 95 % confidence intervals (95 % CI) was used to investigate the association between DM and its subtypes with the AMI outcomes. RESULTS: Out of 2,587,615 patients, there were 29,250 (1.1 %) T1DM and 1,032,925 (39.9 %) T2DM patients. After multivariable adjustment, patients with T1DM had increased odds of MACCE (aOR 1.20, 95 % CI 1.09-1.31), all-cause mortality (aOR 1.20, 95 % CI 1.08-1.33) and major bleeding (aOR 1.28, 95 % CI 1.13-1.44), whilst T2DM patients had increased odds of MACCE (aOR 1.03, 95 % CI 1.01-1.05) and ischemic stroke (aOR 1.09, 95 % CI 1.05-1.13), compared to NDM patients. The adjusted odds of receiving percutaneous coronary intervention were lower in both T1DM and T2DM patients (aOR 0.70, 95 % CI 0.66-0.75 and aOR 0.95, 95 % CI 0.94-0.96, respectively), but T2DM patients showed higher utilization of composite percutaneous and surgical revascularization (aOR 1.03, 95 % CI 1.03-1.04) compared to NDM patients. CONCLUSIONS: DM patients presenting with AMI have worse in-hospital clinical outcomes compared to NDM patients. There are important DM type-related differences with T1DM patients having overall worse outcomes and receiving less overall revascularization.

Evaluation of the endothelial function in hypertensive patients with 13N-ammonia PET.

BACKGROUND: Essential hypertension is one of the main risk factors for the development of coronary artery disease (CAD). Hypertension causes endothelial dysfunction which is considered an early sign for the development of CAD. Positron emission tomography is a non-invasive imaging technique that measures myocardial blood flow (MBF), allowing us to identify patients with endothelial dysfunction. METHODS AND RESULTS: 19 patients without comorbidities recently diagnosed hypertensive, as well as 21 healthy volunteers were studied. A three-phase (rest, cold pressor test, and adenosine-induced hyperemia) (13)N-ammonia PET was performed, and MBF was measured. Endothelial-Dependent Vasodilation Index, ΔMBF, and coronary flow reserve (CFR) were calculated for each patient. Hypertensive patients had a significantly higher systolic and diastolic blood pressures compared with the control group (134.6 ± 11.7/86.4 ± 10.6 mm Hg and 106.0 ± 11.8/71.4 ± 6.6 mm Hg, respectively, P < .001). The ENDEVI (1.28 ± 0.26 vs 1.79 ± 0.30, P < .001), the ΔMBF (0.81 ± 0.50 vs 0.25 ± 0.21, P < .001) and the CFR (2.18 ± 0.88 vs 3.17 ± 0.68, P = .001) were significantly lower in the hypertensive patients compared to the control group, 84% of the former group had endothelial dysfunction i.e., ENDEVI < 1.5 and 58% had vasomotor abnormalities, i.e., CFR < 2.5. CONCLUSIONS: In this study, we showed that recently diagnosed hypertensive patients have coronary endothelial dysfunction and vasomotor disturbances which are early signs for the development of CAD.

Endothelial dysfunction in patients with antiphospholipid syndrome assessed with positron emission tomography.

BACKGROUND: There is limited knowledge about endothelial dysfunction in patients with primary antiphospholipid syndrome (PAPS). The purpose of this study was to evaluate endothelial function in patients with PAPS assessed by positron emission tomography. METHODS AND RESULTS: A 3-phase protocol--rest, cold pressor test (CPT), and adenosine positron emission tomography with nitrogen 13 ammonia--was used in 18 patients with PAPS and 18 healthy volunteers (HVs). Myocardial blood flow (MBF) was measured in each phase, with calculation of the endothelial-dependent vasodilation index, the increase in the MBF in response to CPT, and the myocardial flow reserve. An important trend was found in the myocardial flow reserve (2.76 +/- 1.04 in PAPS group vs 3.27 +/- 0.72 in HV group, P > .05), in the endothelial-dependent vasodilation index (1.19 +/- 0.31 in PAPS group vs 1.55 +/- 0.37 in HV group, P < .05), and in the percent change in the MBF in response to CPT (from rest) (19% +/- 31% in PAPS group vs 55% +/- 37% in HV group, P < .05). CONCLUSION: The CPT results obtained in this study showed that the PAPS patients studied have endothelial dysfunction.

[Experience with the use of positron emission tomography (PET) in Mexico]. / Experiencia en México de la utilización de la tomografía por emisión de positrones (PET).

BACKGROUND: Positron Emission Tomography (PET) is a non-invasive imaging diagnostic tool that allows the study of specific biochemical processes using labeled molecules that closely mimic endogenous molecules. The two radiopharmaceuticals used in our facility are 13N-Ammonia and 18F-2-deoxy-2 fluor D-glucose (18F-FDG). 18F-FDG is the most common radiopharmaceutical used both at our Unit as well as worldwide, as it allows the study of tumor activity, the heart's metabolic activity, distinguish viable from non-viable myocardium and assess cerebral metabolism, among others. OBJECTIVES: Describe the experience in the use of PET scan in our country in the fields of oncology, cardiology and neuropsychiatry. METHODS: We performed an observational, retrospective, cross-sectional, and descriptive study. RESULTS: We analyzed a total of 1,154 studies performed at the UNAM-PET-Cyclotron Unit belonging to the Faculty of Medicine at the National Autonomous University of Mexico (UNAM). From the studies, 72.1% (832) corresponded to oncology, whereas 18.5% (213) and 9.4% (109) belonged to cardiology and neuropsychiatry, respectively. CONCLUSIONS: The studies performed at the UNAM-PET-Cyclotron Unit places it as the site with the largest PET experience in our country.

Comparison of 18FDG PET with thallium SPECT in the assessment of myocardial viability. A segmental model analysis.

BACKGROUND: In patients with myocardial infarction and left ventricular dysfunction, the evidence of myocardial viability is primordial. There are some methods to detect the presence of myocardial viability, 201 thallium reinjection SPECT protocol represents the most common radioisotopic technique to evaluate it. Positron emission tomography (PET) using FDG is considered the gold standard. The aim of this study was to compare globally and by segments the value of both techniques in the detection of viable myocardium. METHODS: Twenty-three consecutive patients with previous myocardial infarction and left ventricular dysfunction were studied. All of them underwent into a SPECT perfusion scan and a FDG PET study to asses myocardial viability. Each study was performed in less than one week between the other. For the analysis, the myocardium was divided into 17 segments. A visual semi-quantitative analysis was carried out according to the following score indicating radiotracer uptake: O = normal to 4 = absent. Myocardial viability was defined as the presence of normal, mildly or moderately reduced radiotracer uptake. The scores obtained by PET were compared to those obtained in SPECT. A statistical analysis was performed using the SPSS v. 10. RESULTS: 391 segments were analyzed. PET detected viability in 130 segments that had been defined as non-viable by SPECT. No differences in the analysis by vascular territories were found. Thirty percent of the segments that were defined as non viable by SPECT were viable by PET, meanwhile only 1% of the segments detected viable by SPECT were considered non viable with PET. CONCLUSIONS: FDG PET study represents a better technique to detect myocardial viability, compared to thallium reinjection SPECT protocol. By this study we have demonstrated that more of 3 of each 10 studies may be diagnosed as non viable where viability is present.

Comparison of 18FDG PET with thallium SPECT in the assessment of myocardial viability. A segmental model analysis

BACKGROUND: In patients with myocardial infarction and left ventricular dysfunction, the evidence of myocardial viability is primordial. There are some methods to detect the presence of myocardial viability, 201 thallium reinjection SPECT protocol represents the most common radioisotopic technique to evaluate it. Positron emission tomography (PET) using FDG is considered the gold standard. The aim of this study was to compare globally and by segments the value of both techniques in the detection of viable myocardium. METHODS: Twenty-three consecutive patients with previous myocardial infarction and left ventricular dysfunction were studied. All of them underwent into a SPECT perfusion scan and a FDG PET study to asses myocardial viability. Each study was performed in less than one week between the other. For the analysis, the myocardium was divided into 17 segments. A visual semi-quantitative analysis was carried out according to the following score indicating radiotracer uptake: O = normal to 4 = absent. Myocardial viability was defined as the presence of normal, mildly or moderately reduced radiotracer uptake. The scores obtained by PET were compared to those obtained in SPECT. A statistical analysis was performed using the SPSS v. 10. RESULTS: 391 segments were analyzed. PET detected viability in 130 segments that had been defined as non-viable by SPECT. No differences in the analysis by vascular territories were found. Thirty percent of the segments that were defined as non viable by SPECT were viable by PET, meanwhile only 1% of the segments detected viable by SPECT were considered non viable with PET. CONCLUSIONS: FDG PET study represents a better technique to detect myocardial viability, compared to thallium reinjection SPECT protocol. By this study we have demonstrated that more of 3 of each 10 studies may be diagnosed as non viable where viability is present.

[Myocardial viability, its importance for the therapeutic decision]. / Viabilidad miocárdica, su importancia en la decisión terapéutica.

Myocardial viability detection is essential in patients with history of myocardial infarction whom develop ventricular dysfunction. Its detection influences the therapeutic decisions and the prognosis. Medical therapy in patients with ventricular dysfunction due to myocardial infarction and myocardial viability has been associated with higher morbidity and mortality rates than revascularization therapy, as well as improvements in the systolic function. Several imaging techniques used in the recognition of myocardial viability are available; these techniques are based on the assessment of the ventricular motion posterior to inotropic agents stimulation or on the demonstration of metabolic activity at the dysfunctional regions. In this study, some important aspects of each technique are reviewed, doing special emphasis in the utility of the Positron Emission Tomography (PET) which has been considered as the "gold standard" in the detection of myocardial viability.

[Evaluation of coronary artery disease by myocardial perfusion imaging in women]. / Evaluación de enfermedad arterial coronaria con imágenes de perfusión miocárdica en mujeres.

UNLABELLED: The early diagnosis of coronary artery disease continues to be a challenge in women because non invasive diagnostic tests to evaluate ischemia, such as stress test are less accurate in this group of patients. The aim of the study was to assess the value of myocardial perfusion imaging with SPECT for the detection of ischemia. METHODS: We studied 151 consecutive women who were assessed by SPECT with Tc-99m Sestamibi, stress test and coronary angiography. Sensitivity and specificity was calculated for each test. RESULTS: The prevalence of angiographycally significant coronary artery disease was 71.5%. The sensitivity and specificity of myocardial perfusion imaging for the detection of ischemia was 91.6% and 87.9% respectively. The sensitivity and specificity of stress test was 43% and 96.1%. Accuracy of myocardial perfusion imaging was higher in the group of patients older than 50 years of age, in whom severe coronary artery disease was more prevalent. CONCLUSIONS: The result of this study suggest that myocardial perfusion imaging is a very useful tool for detection of ischemia in women with CAD, especially for those over 50 years of age, being superior to other non invasive tests as stress test.

[Evaluation of coronary flow by means of PET in the Mexican population without coronary artery disease]. / Valoración del flujo coronario mediante PET en lapoblación mexicana sin enfermedad arterial coronaria.

UNLABELLED: Coronary artery disease (CAD) represents the principal cause of morbidity and mortality in our environment. Positron emission tomography (PET) is a new technique in our country that allows the assessment of myocardial perfusion and the absolute quantification of the coronary blood flow (CBF) through the utilization of radiotracers using the same criteria employed in conventional nuclear cardiology. CBF normal values have been determined in other populations around the world. No studies in our country assessing in a non-invasive way the CBF have been published before. The quantification of CBF in healthy population is important to establish a standard measure and determine through it, the effects of the many diseases that change the coronary blood flow. The quantification of the CBF, the calculation of coronary blood flow reserve (CFR) and the endothelium dependent vasodilatation index (EDVI) through PET is possible performing three different acquisition stages: rest, cold pressor test (CPT) and pharmacologic stress using Ammonia as radiotracer. The aim of this study was to evaluate the CBF, the CFR and the EDVI in healthy Mexican volunteers. RESULTS: Global basal CBF was 0.34 (+/- 0.09) mL/g/min, during CPT increased to 0.55 (+/- 0.17) mL/g/min and during the stress increased to 1.18 (+/- 0.25). CFR was 3.5 (+/- 0.65) and EDVI was 1.55 (+/- 0.33). CONCLUSIONS: CFR and EDVI values obtained in Mexican healthy population correlates very well with those reported in the literature. This values represents a reference to further research that use this technology.

[Inflammatory activity in Takayasu arteritis. Detection through positron emission tomography (PET)]. / Actividad inflamatoria en arteritis de Takayasu. Detección mediante tomografía por emisión de positrones (PET).

Takayasu arteritis (TA) is a chronic disease that affects mainly the aorta. Its etiology is still unknown, nevertheless it predominates in women and initiates primarily in the youth. This disease seems to have two different stages, an early stage that is characterized by an inflammatory process and a later stage characterized by vascular occlusion. Unitl now, diagnosis and classification of TA are made clinically, based on ACR; criteria and imaging studies as computed tomography and aorta angiographies. Currently, new imaging, non invasive studies, such as magnetic resonance (MRI) and positron emission tomography (PET) are being used. PET technique could be helpful in the diagnosis and detection of inflammatory activity in patients with TA because of its capacity to detect increased metabolism. We present the case of a female patient with TA diagnosis, which demonstrated clinical inflammatory activity that was corroborated by laboratory studies, MRI and PET.

[Study of myocardial viability: comparison of PET and MRI]. / Estudio de la viabilidad miocárdica: comparación de tomografía por emisión de positrones y resonancia magnética.

BACKGROUND: In the last years, few methods for the assessment of myocardial viability have been developed. Now a days the gold standard test for this purpose is the Positron Emission Tomography (PET). Recently, the expansion of Cardiovascular Magnetic Resonance imaging (MRI) has promoted the research for indexes or scores than can predict myocardial viability; so far, the late enhancement has proved to be one of the most accurate scores. The purpose of this study is to establish a correlation between the information of PET with the results of MRI in the assessment of myocardial viability. Late enhancement patterns and segmental mobility were compared. Sensitivity, specificity and positive and negative predictive values were calculated. SPSS v. 10 program was used for the statistic analysis. METHODS: 17 patients with diagnosis of myocardial infarction were enrolled. All of them underwent into a myocardial viability detection PET study and into a cardiovascular magnetic resonance study using a late enhancement technique. Results were interpreted by experts. The 17 segments model of The American Heart Association was used. RESULTS: A total of 289 myocardial segments were analyzed, by PET 239 (82%) viable segments and 50 (17.3%) of non viable segments were detected, meanwhile by MRI 210 (72.6%) and 79 (27.4%) of viable and non viable myocardial segments respectively were found. Both techniques correlate 75% of the times and when vascular territories were analyzed, a good correlation was also established. CONCLUSIONS: MRI is an adequate technique to determine viability since it has good correlation with PET. This is the first study realized in Latin America that compares PET and MRI in the diagnosis of myocardial viability.

Estudio de la viabilidad miocárdica: Comparación de tomografía por emisión de positrones y resonancia magnética / Study of myocardial viability: Comparison of PET and MRI

Introducción: En los últimos años se han desarrollado diversos métodos que permiten evaluar zonas de miocardio viable. Actualmente el estándar de oro para este propósito es la Tomografía por Emisión de Positrones (PET). Recientemente, con el advenimiento y expansión de la resonancia magnética cardiovascular (RMCV), se han buscado diferentes índices y marcadores de viabilidad en este método de imagen; encontrándose hasta ahora que el reforzamiento tardío es uno de los marcadores más precisos para este fin. En este trabajo se busca correlacionar los datos obtenidos en PET con aquellos que muestra la RMCV en el estudio de la viabilidad miocárdica. Método: Se estudiaron 17 pacientes con diagnóstico de infarto del miocardio, a los cuales se les practicó una determinación de viabilidad miocárdica con Fluoro-18-deoxiglucosa.(PET-FDG) y un estudio para detección de viabilidad miocárdica mediante resonancia magnética. El periodo de tiempo entre ambos estudios fue en todos los casos menor a una semana. Los resultados fueron interpretados por expertos. Se utilizó el modelo de 17 segmentos de la American Heart Association. El patrón de reforzamiento tardío observado en el estudio de resonancia magnética fue comparado con la movilidad segmentaria. Se obtuvo sensibilidad, especificidad y factores predictivos tanto positivo como negativo de la RMCV en el diagnóstico de viabilidad. Los resultados de ambas técnicas fueron comparados utilizando el programa SPSS v. 10. Resultados: Se estudiaron 289 segmentos miocárdicos, PET detectó 239 (82.7%) segmentos viables y 50 (17.3%) segmentos no viables, con RMCV se encontraron 210 (72.6%) segmentos viables y 79 (27.4%) segmentos no viables. Ambas técnicas coincidieron el 75% de las veces y al analizarlo por territorio coronario específico la correlación fue muy buena. Conclusiones: La RMCV es una técnica adecuada para la evaluación de viabilidad miocardica. Este estudio es el primero en Latinoamérica que utiliza la RMCV y el PET de forma conjunta.

Background: In the last years, few methods for the assessment of myocardial viability have been developed. Now a days the gold standard test forthis purpose is the Positron Emission Tomography (PET). Recently, the expansion of Cardiovascular Magnetic Resonance imaging (MRI) has promoted the research for indexes or scores than can predict myocardial viability; so far, the late enhancement has proved to be one of the most accurate scores. The purpose of this study is to establish a correlation between the information of PET with the results of MRI in the assessment of myocardial viability. Late enhancement patterns and segmental mobility were compared. Sensitivity, specificity and positive and negative predictive values were calculated. SPSS v. 10 program was used forthe statistic analysis. Methods: 17 patients with diagnosis of myocardial infarction were enrolled. All of them underwent into a myocardial viability detection PET study and into a cardiovascular magnetic resonance study using a late enhancement technique. Results were interpreted by experts. The 17 segments model of The American Heart Association was used. Results: A total of 289 myocardial segments were analyzed, by PET 239 (82%) viable segments and 50 (17.3%) of non viable segments were detected, meanwhile by MRI 210 (72.6%) and 79 (27.4%) of viable and non viable myocardial segments respectively were found. Both techniques correlate 75% of the times and when vascular territories were analyzed, a good correlation was also established. Conclusions: MRI is an adequate technique to determine viability since it has good correlation with PET. This is the first study realized in Latin America that compares PET and MRI in the diagnosis of myocardial viability.

Actividad inflamatoria en arteritis de Takayasu. Detección mediante tomografía por emisión de positrones (PET) / Inflammatory activity in Takayasu arteritis. Detection through positron emission tomography (PET)

La arteritis de Takayasu (AT), es una enfermedad crónica que afecta principalmente a la aorta y sus ramas. Su etiología aún es desconocida, sin embargo se sabe que existe un predominio por el género femenino y que inicia generalmente en los jóvenes. La enfermedad parece tener dos fases, una temprana que se caracteriza por un proceso inflamatorio y otra fase crónica que es caracterizada por oclusión vascular. Hasta ahora el diagnóstico y la clasificación son predominantemente clínicos basados en los criterios del ACR y apoyados por estudios de imagen como la panaortografia o la tomografia computada. Actualmente existen nuevos estudios de diagnóstico por imagen como la resonancia magnética (RM) y la tomografia por emisión de positrones (PET), esta última por su capacidad para valorar el metabolismo podría ser de gran ayuda en el diagnóstico, detección de actividad inflamatoria y seguimiento de los pacientes con AT. Se presenta el caso de una paciente de sexo femenino quien tiene diagnóstico de AT, con actividad inflamatoria tanto por clínica, laboratorio, RM y PET.

Takayasu arteritis (TA) is a chronic disease that affects principally the aorta. Its etiology persists unknown, nevertheless it is well known that predominates in females and initiates primarily in the youth. This disease seems to has two different stages, an early stage that is characterized by an inflammatory process and a later stage characterized by vascular occlusion. Until now, diagnosis and classification of TA are clinically, based on ACR criteria and imaging studies as computed tomography and aorta angiographies. Actually new imaging, non invasive studies as magnetic resonance (MRI) and positron emission tomography (PET) are allowed. PET technique could be helpfull in the diagnosis and in the detection of inflammatory activity in patients with TA because its capacity to detect increased metabolism. We present the case of a female patient with TA diagnosis, which demonstrated clinical inflammatory activity and was corroborated by laboratory studies, MRI and PET.

Viabilidad miocárdica: su importancia en la decisión terapéutica / Myocardial viability: its importance for the therapeutic decision

Resumen La búsqueda de viabilidad miocárdica en el paciente con infarto del miocardio y disfunción ventricular es una práctica casi obligada. La importancia de su detección radica en el impacto tanto pronóstico como en la decisión terapéutica que se debe de tomar en estos pacientes. El empleo de tratamiento médico en pacientes con disfunción ventricular y miocardio viable se ha asociado a una elevada tasa de morbi-mortalidad, mientras que la realización de revascularización se asocia a una mejora en la función sistólica del ventrículo izquierdo, así como a una disminución en la incidencia de eventos cardíacos y una prolongación en la expectativa de vida. Existen diversas técnicas de imagen empleadas para el reconocimiento de viabilidad miocárdica en pacientes con cardiopatía isquémica basadas en la valoración de la movilidad parietal tras estímulos inotrópicos, en la presencia de integridad celular o en la demostración de persistencia de actividad metabólica dentro de estas regiones de miocardio disfuncional. En el presente trabajo se revisan algunos puntos importantes de cada una de estas técnicas, haciendo énfasis especial en la utilidad de la técnica de Tomografía por Emisión de Positrones (PET) la cual es considerada como el "estándar de oro" en la detección no invasiva de viabilidad miocárdica.

Summary Myocardial viability detection is essential in patients with history of myocardial infarction whom develop ventricular dysfunction. Its detection influences the therapeutic decisions and the prognosis. Medical therapy in patients with ventricular dysfunction due to myocardial infarction and myocardial viability has been associated with higher morbidity and mortality rates than revascularization therapy, as well as improvements in the systolic function. Several imaging techniques used in the recognition of myocardial viability are available; these techniques are based on the assessment of the ventricular motion posterior to inotropic agents stimulation or on the demonstration of metabolic activity at the dysfunctional regions. In this study, some important aspects of each technique are reviewed, doing special emphasis in the utility of the Positron Emission Tomography (PET) which has been considered as the "gold standard" in the detection of myocardial viability.

Valoración del flujo coronario mediante PET en la población mexicana sin enfermedad arterial coronaria / Evaluation of coronary flow by means of PET in the Mexican population without coronary artery disease

La enfermedad arterial coronaria (EAC) representa la primera causa de morbi mortalidad en nuestro medio. La tomografía por emisión de positrones (PET) es una técnica novedosa en nuestro país mediante la cual es posible valorar la perfusión miocárdica a través de radiotrazadores, lo que permite detectar defectos de perfusión utilizando los mismos criterios que en cardiología nuclear. A su vez, a través del estudio del flujo coronario (FC) es posible detectar la EAC en sus etapas más tempranas. El FC ha sido determinado en otras poblaciones a nivel mundial, sin embargo, hasta el momento no existen estudios en nuestro país que lo hayan valorado de manera no invasiva. La importancia de determinar el FC en voluntarios sanos radica en establecer una base para poder comparar estos resultados con los encontrados en pacientes con diferente patología que afecte el flujo coronario. Para la determinación del FC y la reserva de flujo coronario (RFC) y del índice de vasodilatación dependiente de endotelio (IVED) mediante PET se realizan 3 mediciones en 3 fases distintas: reposo, estimulación con frío (CPT) y esfuerzo farmacológico, con la utilización de amonio. Objetivo: Determinar el FC en las tres fases en población sana con la utilización de amonio-PET. Resultados: El FC global basal fue de 0.34 (±0.09) mL/g/min, durante el CPT incrementó a 0.55 (±0.17) mL/g/min y con el estrés llegó a 1.18 (±0.25). La RFC fue de 3.5 (±0.65) y el IVED de 1.55 (±0.33). Conclusiones: Los valores obtenidos de RFC y de IVED en población mexicana sana coincide con los reportados en la literatura. Estos valores representan una base de referencia para las investigaciones futuras con esta tecnología en nuestro país.

Coronary artery disease (CAD) represents the principal cause of morbidity and mortality in our environment. Positron emission tomography (PET) is a new technique in our country that allows the assessment of myocardial perfusion and the absolute quantification of the coronary blood flow (CBF) through the utilization of radiotracers using the same criteria employed in conventional nuclear cardiology. CBF normal values have been determined in other populations around the world. No studies in our country assessing in a non-invasive way the CBF have been published before. The quantification of CBF in healthy population is important to establish a standard measure and determine through it, the effects of the many diseases that change the coronary blood flow. The quantification of the CBF, the calculation of coronary blood flow reserve (CFR) and the endothelium dependent vasodilatation index (EDVI) through PET is possible performing three different acquisition stages: rest, cold pressor test (CPT) and pharmacologic stress using Ammonia as radiotracer. The aim of this study was to evaluate the CBF, the CFR and the EDVI in healthy Mexican volunteers. Results: Global basal CBF was 0.34 (±0.09) mL/g/min, during CPT increased to 0.55 (±0.17) mL/g/min and during the stress increased to 1.18 (±0.25). CFR was 3.5 (±0.65) and EDVI was 1.55 (±0.33). Conclusions: CFR and EDVI values obtained in Mexican healthy population correlates very well with those reported in the literature. This values represents a reference to further research that use this technology.

Evaluación de enfermedad arterial coronaria con imágenes de perfusión miocárdica en mujeres / Evaluation of coronary artery disease by myocardial perfusion imaging in women

El diagnóstico precoz de la enfermedad arterial coronaria constituye un reto en las mujeres, en quienes los métodos diagnósticos no invasivos para evaluar isquemia tales como prueba de esfuerzo tienen menor precisión. El objetivo del estudio fue conocer la utilidad de las imágenes de perfusión miocárdica con SPECT para la evaluación de isquemia en mujeres. Métodos: Se estudiaron 151 mujeres a las cuales se les realizaron imágenes de perfusión miocárdica con SPECT y Tc-99m- Sestamibi, electrocardiografía de esfuerzo, y angiografía. Se evaluó la sensibilidad y especificidad de cada prueba. Resultados: La prevalencia de enfermedad arterial coronaria angiográficamente significativa fue de 71.5%. La sensibilidad y especificidad de las imágenes de SPECT para la detección de isquemia fue de 91.6% y 87.9%. La sensibilidad y especificidad de la electrocardiografía de esfuerzo fue de 43% y 96.1%. La precisión de las imágenes de SPECT es mayor en pacientes mayores de 50 años, en las cuales se encontró mayor prevalencia y severidad de la enfermedad arterial coronaria. Conclusiones: Las imágenes de perfusión miocárdica con SPECT son de gran utilidad para la detección de isquemia en mujeres con enfermedad arterial coronaria, sobre todo en mayores de 50 años, siendo superior a la electrocardiografía de esfuerzo.

The early diagnosis of coronary artery disease continues to be a challenge in women because non invasive diagnostic tests to evaluate ischemia, such as stress test are less accurate in this group of patients. The aim of the study was to assess the value of myocardial perfusion imaging with SPECT for the detection of ischemia. Methods: We studied 151 consecutive women who were assessed by SPECT with Tc-99m Sestamibi, stress test and coronary angiography. Sensitivity and specificity was calculated for each test. Results: The prevalence of angiographycally significant coronary artery disease was 71.5%. The sensitivity and specificity of myocardial perfusion imaging for the detection of ischemia was 91.6% and 87.9% respectively. The sensitivity and specificity of stress test was 43% and 96.1%. Accuracy of myocardial perfusion imaging was higher in the group of patients older than 50 years of age, in whom severe coronary artery disease was more prevalent. Conclusions: The result of this study suggest that myocardial perfusion imaging is a very useful tool for detection of ischemia in women with CAD, especially for those over 50 years of age, being superiorto other non invasive tests as stress test.

[Positron emission tomography (PET): a useful tool for the assessment of cardiac metabolism]. / Tomografía por emisión de positrones (PET): Una herramienta util para el estudio del metabolismo cardiaco.

Under normal conditions, myocardial metabolism is based on the oxidation of fatty acids and in a lesser extent carbohydrates. Cardiac function depends upon an adequate supplement of adenosine triphosphate (ATP) by these substrates. However, the main source of energy is susceptible to change upon a various physiologic (exercise) as well as pathologic (ischemia-reperfusion) conditions. Recently, carnitine has gained attention as a modulator of fatty acids and carbohydrates metabolism by means of modifying intramitochondrial Acetyl-CoA/CoA ratio. Disturbances in fatty acids and carbohydrates metabolism in the myocardium have been associated with cardiovascular diseases (chronic ischemic disease, ventricular hypertrophy and dilated cardiomyopathy). The evaluation of cardiac metabolism attains great value regarding diagnosis, treatment and prognosis of these diseases. Currently, positron emission tomography (PET) is one of the preferred methods to evaluate cardiac energy metabolism in clinical practice. In PET images the tracers most commonly used are 11C-palmitate, 11C-acetate y 18Fluoro-2-deoxyglucose (FDG), the first two are employed to assess fatty acids oxidation and FDG is used to evaluate carbohydrates metabolism.