¿Conocemos los límites del corazón?

Heart diseasesMalalties del corEnfermedades del corazó

Case report: Removal of a subcutaneous implantable cardiac defibrillator in a pediatric patient with hypertrophic cardiomyopathy after a septal myectomy. Insights on current indications of type of ICD in children with hypertrophic cardiomyopathy and left ventricular tract obstruction

Hypertrophic cardiomyopathy; Myectomy; Sudden cardiac deathMiocardiopatia hipertròfica; Miectomia; Mort cardíaca sobtadaMiocardiopatía hipertrófica; Miectomía; Muerte cardíaca súbitaHypertrophic cardiomyopathy is a heart muscle disease with an annual incidence between 0.24 and 0.47/100000 in childhood. Sudden cardiac death is the most common cause of death in this population. Although some medical treatment can decrease the risk of sudden cardiac death, implantable cardioverter defibrillator continues to be the most reliable treatment. Different types of devices and programming strategies can be used in patients with hypertrophic cardiomyopathy depending on each center and specific patient condition. We report a pediatric patient affected with hypertrophic cardiomyopathy who had and ICD implantation in primary prevention. Four years later he developed symptomatic left ventricular outflow tract obstruction and a surgical septal myectomy was performed. After the myectomy the patient developed complete left bundle branch block on his 12 lead ECG, and unfortunately none of the S-ICD vectors were suitable after the myectomy and it had to be explanted and replaced for a new transvenous ICD

Clinical Features and Natural History of Preadolescent Nonsyndromic Hypertrophic Cardiomyopathy

Childhood hypertrophic cardiomyopathy; Outcomes; PhenotypeMiocardiopatía hipertrófica infantil; Resultados; FenotipoMiocardiopatia hipertròfica infantil; Resultats; FenotipBackground Up to one-half of childhood sarcomeric hypertrophic cardiomyopathy (HCM) presents before the age of 12 years, but this patient group has not been systematically characterized. Objectives The aim of this study was to describe the clinical presentation and natural history of patients presenting with nonsyndromic HCM before the age of 12 years. Methods Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children diagnosed with HCM younger than 12 years were collected and compared with those from 568 children diagnosed between 12 and 16 years. Results At baseline, 339 patients (53.6%) had family histories of HCM, 132 (20.9%) had heart failure symptoms, and 250 (39.2%) were prescribed cardiac medications. The median maximal left ventricular wall thickness z-score was 8.7 (IQR: 5.3-14.4), and 145 patients (27.2%) had left ventricular outflow tract obstruction. Over a median follow-up period of 5.6 years (IQR: 2.3-10.0 years), 42 patients (6.6%) died, 21 (3.3%) underwent cardiac transplantation, and 69 (10.8%) had life-threatening arrhythmic events. Compared with those presenting after 12 years, a higher proportion of younger patients underwent myectomy (10.5% vs 7.2%; P = 0.045), but fewer received primary prevention implantable cardioverter-defibrillators (18.9% vs 30.1%; P = 0.041). The incidence of mortality or life-threatening arrhythmic events did not differ, but events occurred at a younger age. Conclusions Early-onset childhood HCM is associated with a comparable symptom burden and cardiac phenotype as in patients presenting later in childhood. Long-term outcomes including mortality did not differ by age of presentation, but patients presenting at younger than 12 years experienced adverse events at younger ages.This work was supported by the British Heart Foundation (grant FS/16/72/32270) to Drs Norrish and Kaski. This work is (partly) funded by the National Institute for Health Research Great Ormond Street Hospital Biomedical Research Centre. Dr Norrish is supported by Great Ormond Street Hospital Children’s Charity. Drs Field and Kaski are supported by Max’s Foundation and Great Ormond Street Hospital Children’s Charity. Dr Kaski is supported by a Medical Research Council–National Institute for Health Research Clinical Academic Research Partnership award. This work was financially supported by the Foundation for Paediatric Research of Finland (Dr Ojala). Dr Fernandez has received speaker fees from Sanofi-Genzyme. Dr Kubus is supported by MH CZ – DRO, Motol University Hospital (00064203). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose

Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy

Child; Death; Hypertrophic cardiomyopathyNiño; Muerte; Miocardiopatía hipertróficaNen; Mort; Miocardiopatia hipertròficaBackground: Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort. Methods: The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1–16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids). Results: MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3–9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk. Conclusions: In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM

The relationship between maximal left ventricular wall thickness and sudden cardiac death in childhood onset hypertrophic cardiomyopathy

Background: Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort. Methods: The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1–16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids). Results: MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3–9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk. Conclusions: In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM

Clinical Features and Natural History of Preadolescent Nonsyndromic Hypertrophic Cardiomyopathy

BACKGROUND Up to one-half of childhood sarcomeric hypertrophic cardiomyopathy (HCM) presents before the age of 12 years, but this patient group has not been systematically characterized. OBJECTIVES The aim of this study was to describe the clinical presentation and natural history of patients presenting with nonsyndromic HCM before the age of 12 years. METHODS Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children diagnosed with HCM younger than 12 years were collected and compared with those from 568 children diagnosed between 12 and 16 years. RESULTS At baseline, 339 patients (53.6%) had family histories of HCM, 132 (20.9%) had heart failure symptoms, and 250 (39.2%) were prescribed cardiac medications. The median maximal left ventricular wall thickness z-score was 8.7 (IQR: 5.3-14.4), and 145 patients (27.2%) had left ventricular outflow tract obstruction. Over a median follow-up period of 5.6 years (IQR: 2.3-10.0 years), 42 patients (6.6%) died, 21 (3.3%) underwent cardiac transplantation, and 69 (10.8%) had life-threatening arrhythmic events. Compared with those presenting after 12 years, a higher proportion of younger patients underwent myectomy (10.5% vs 7.2%; P = 0.045), but fewer received primary prevention implantable cardioverter-defibrillators (18.9% vs 30.1%; P = 0.041). The incidence of mortality or life-threatening arrhythmic events did not differ, but events occurred at a younger age. CONCLUSIONS Early-onset childhood HCM is associated with a comparable symptom burden and cardiac phenotype as in patients presenting later in childhood. Long-term outcomes including mortality did not differ by age of presentation, but patients presenting at younger than 12 years experienced adverse events at younger ages. (C) 2022 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.Peer reviewe

Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy

Background: Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort. Methods: The study cohort comprised 1075 children (mean age, 10.2 years [+/- 4.4]) diagnosed with HCM (1-16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids). Results: MLVWT Z score was = 10 to = 20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score >= 20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3-9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores = 10 to = 20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk. Conclusions: In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM.Peer reviewe

Diagnóstico y tratamiento de la miocarditis aguda en pediatría

Introducción y objetivos: La miocarditis es una enfermedad inflamatoria del miocardio, secundaria a una infección vírica en la mayoría de los casos. El diagnóstico de certeza se establece por la biopsia endomiocárdica (BEM), aunque al tratarse de una técnica invasiva, su uso está muy restringido en la población pediátrica. El cuadro suele resolverse de forma espontánea, pero algunos pacientes pueden fallecer o presentar una disfunción ventricular severa que precise trasplante cardíaco. Ningún tratamiento ha demostrado mejorar el pronóstico. El objetivo de este estudio es revisar las características de una serie de pacientes pediátricos con miocarditis aguda, describir su evolución, los criterios de mal pronóstico y la utilidad y los riesgos de las diferentes técnicas diagnósticas, como la BEM. Describiremos la utilidad del tratamiento antiviral e inmunosupresor en una población seleccionada de pacientes. Material y métodos: revisamos todos los pacientes < 18 años que han ingresado en el Hospital Materno Infantil de la Vall d´Hebron con el diagnóstico de miocarditis aguda desde abril de 2007 hasta septiembre de 2018. Se revisan las características clínicas y demográficas, los resultados de las diferentes exploraciones complementarias así como la utilidad de la BEM en esta población. Se comparan los resultados inmunohistoquímicos de la BEM con los observados en pacientes con miocardiopatía de origen genético. Se estudia la efectividad del tratamiento médico comparando la evolución de los pacientes tratados con la de una cohorte histórica de características similares que no recibieron tratamiento específico. Resultados: 41 pacientes (25 varones, 16 mujeres, edad mediana 25 meses) presentaron 42 episodios de miocarditis. El diagnóstico se realizó por BEM en 14/42 casos (33.3%), por resonancia magnética en 27/42 (64.3%) y por clínica en 1/42 paciente (2.4%). Con una mediana de seguimiento de 47 meses (entre 7 y 140 meses), se produjo una resolución completa del cuadro con normalización de la FEVI y del DTDVI en 33/42casos (78.5%). El virus más frecuentemente implicado fue el PVB19 (9/42 casos, 21.4%) seguido por el enterovirus (5/42 casos, 11.9%). Fallecieron 4/41 pacientes (9.7%) y 5/41 (12.2%) precisaron un trasplante cardíaco. En el análisis univariado, los factores que se relacionaron con una peor evolución (fallecimiento del paciente o trasplante) fueron la necesidad de ECMO al ingreso (p=0.041), una fracción de eyección del ventrículo izquierdo (FEVI) inferior al 35% (p=0.02) y la disfunción del ventrículo derecho (p=0.02). En el análisis multivariado sólo la FEVI tuvo significación estadística (p=0.007). En cuanto a los hallazgos anatomopatológicos se observó que ningún dato era específico de miocarditis aguda y que 3/5 pacientes (60%) con miocardiopatía dilatada de origen genético cumplían los criterios de inmunohistológicos de miocarditis. Desde febrero de 2015, los casos más graves recibieron tratamiento con inmunosupresión o antiviral en función del resultado anatomopatológico y de la PCR vírica en la BEM. En total fueron tratados 9 pacientes y su evolución se comparó con una cohorte histórica de 11 pacientes de características similares. La supervivencia libre de trasplante al año fue del 100% en el grupo tratado vs el 63% (p=0.042). A largo plazo, 8/9 pacientes tratados evolucionaron a la curación completa frente a 6/11 (88.9% vs 54.5%, p=0.095) Conclusiones: una FEVI<35% es el único facor de riesgo asociado a una mayor mortalidad o a un mayor riesgo de trasplante. La BEM es una técnica segura y útil para el diagnóstico de miocarditis aguda en la población pediátrica. El tratamiento específico guiado por los resultados de la BEM mejora la FEVI y la evolución de los pacientes a corto plazo.Introduction and objectives: Acute myocarditis is an inflammatory disease of the myocardiumdue to a viral infection in majority ofcases. Diagnosis is performed by obtaining anendomyocardial biopsy (BEM), however it is an invasive technique; its use is not very common in pediatrics. The disease usually resolves itself spontaneously, but some patients may die or have severe ventricular dysfunction, which requires a heart transplant. No treatment has demonstrated to improve the prognosis yet. The aim of this study is to check the characteristics of a series of pediatric patients with acute myocarditis, describe their outcome, the criteria of poor prognosis and the usefulness and risks of different diagnostic techniques, such as BEM. We will describe the usefulness of antiviral and immunosuppressive treatment in a selected population of patients. Material and methods: We reviewed all cases of persons under the age of 18 who had been admitted to Vall d'Hebron Hospital with the diagnosis of acute myocarditis between April 2007 and September 2018. We reviewed clinical and demographic characteristics, diagnostic tests as well as the usefulness of the BEM in this population. Immunohistochemical results of BEM were compared with those observed in a patient population with inheritedcardiomyopathy. The effectiveness of medical treatment was studied by comparing the outcome of treated patients with that of a historical cohort of similar characteristics that did not receive any specific treatment. Results:41 patients (25 men, 16 women, median age 25 months) presented 42 episodes of myocarditis. The diagnosis was performed by BEM in 14/42 cases (33.3%), magnetic resonance in 27/42 (64.3%) and through clinical presentation in 1/42 patient (2.4%). With a median follow-up of 47 months (between 7 and 140 months), a complete resolution of the situation with normalization of left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDD) occurred in 33/42 cases (78.5%). The most frequently implicated virus was PVB19 (9/42 cases, 21.4%) followed by enterovirus (5/42 cases, 11.9%). Four patients died (9.7%) and 5/41 (12.2%) required a heart transplant. In the univariate analysis, the factors that were associated with a poor outcome (death or transplant) were the need for ECMO at admission (p = 0.041), LVEF less than 35% (p = 0.02) and right ventricular dysfunction (p = 0.02). In the multivariate analysis, only the LVEF had statistical significance (p = 0.007). Regarding the anatomopathological findings, it was observed that no data were specific for acute myocarditis and that 3/5 patients (60%) with genetic cardiomyopathy met the immunohistological criteria of myocarditis. From February 2015 the patients with the most severe illness were treated with immunosuppression or antiviral treatment based on the anatomopathologicalresults and the viral PCR in the BEM. A total of 9 patients were treated and their outcomewas compared with a historical cohort of 11 patients with similar characteristics. Transplant-free survival at one year was 100% in the treated group vs. 63% (p = 0.042). In the long term, 8/9 treated patients were able to fully recover in comparison to 6/11 patients of the other group who received standard treatment (88.9% vs. 54.5%, p = 0.095) Conclusions: LVEF <35% is the only risk factor associated with a higher mortality or a higher risk of transplantation. BEM is a safe and useful diagnostic tool in the pediatric population with acute myocarditis. The specific treatment based on the results of the BEM improves LVEF and the outcome of patients in the short term

Diagnóstico y tratamiento de la miocarditis aguda en pediatría

Introducción y objetivos: La miocarditis es una enfermedad inflamatoria del miocardio, secundaria a una infección vírica en la mayoría de los casos. El diagnóstico de certeza se establece por la biopsia endomiocárdica (BEM), aunque al tratarse de una técnica invasiva, su uso está muy restringido en la población pediátrica. El cuadro suele resolverse de forma espontánea, pero algunos pacientes pueden fallecer o presentar una disfunción ventricular severa que precise trasplante cardíaco. Ningún tratamiento ha demostrado mejorar el pronóstico. El objetivo de este estudio es revisar las características de una serie de pacientes pediátricos con miocarditis aguda, describir su evolución, los criterios de mal pronóstico y la utilidad y los riesgos de las diferentes técnicas diagnósticas, como la BEM. Describiremos la utilidad del tratamiento antiviral e inmunosupresor en una población seleccionada de pacientes. Material y métodos: revisamos todos los pacientes < 18 años que han ingresado en el Hospital Materno Infantil de la Vall d´Hebron con el diagnóstico de miocarditis aguda desde abril de 2007 hasta septiembre de 2018. Se revisan las características clínicas y demográficas, los resultados de las diferentes exploraciones complementarias así como la utilidad de la BEM en esta población. Se comparan los resultados inmunohistoquímicos de la BEM con los observados en pacientes con miocardiopatía de origen genético. Se estudia la efectividad del tratamiento médico comparando la evolución de los pacientes tratados con la de una cohorte histórica de características similares que no recibieron tratamiento específico. Resultados: 41 pacientes (25 varones, 16 mujeres, edad mediana 25 meses) presentaron 42 episodios de miocarditis. El diagnóstico se realizó por BEM en 14/42 casos (33.3%), por resonancia magnética en 27/42 (64.3%) y por clínica en 1/42 paciente (2.4%). Con una mediana de seguimiento de 47 meses (entre 7 y 140 meses), se produjo una resolución completa del cuadro con normalización de la FEVI y del DTDVI en 33/42casos (78.5%). El virus más frecuentemente implicado fue el PVB19 (9/42 casos, 21.4%) seguido por el enterovirus (5/42 casos, 11.9%). Fallecieron 4/41 pacientes (9.7%) y 5/41 (12.2%) precisaron un trasplante cardíaco. En el análisis univariado, los factores que se relacionaron con una peor evolución (fallecimiento del paciente o trasplante) fueron la necesidad de ECMO al ingreso (p=0.041), una fracción de eyección del ventrículo izquierdo (FEVI) inferior al 35% (p=0.02) y la disfunción del ventrículo derecho (p=0.02). En el análisis multivariado sólo la FEVI tuvo significación estadística (p=0.007). En cuanto a los hallazgos anatomopatológicos se observó que ningún dato era específico de miocarditis aguda y que 3/5 pacientes (60%) con miocardiopatía dilatada de origen genético cumplían los criterios de inmunohistológicos de miocarditis. Desde febrero de 2015, los casos más graves recibieron tratamiento con inmunosupresión o antiviral en función del resultado anatomopatológico y de la PCR vírica en la BEM. En total fueron tratados 9 pacientes y su evolución se comparó con una cohorte histórica de 11 pacientes de características similares. La supervivencia libre de trasplante al año fue del 100% en el grupo tratado vs el 63% (p=0.042). A largo plazo, 8/9 pacientes tratados evolucionaron a la curación completa frente a 6/11 (88.9% vs 54.5%, p=0.095) Conclusiones: una FEVI<35% es el único facor de riesgo asociado a una mayor mortalidad o a un mayor riesgo de trasplante. La BEM es una técnica segura y útil para el diagnóstico de miocarditis aguda en la población pediátrica. El tratamiento específico guiado por los resultados de la BEM mejora la FEVI y la evolución de los pacientes a corto plazo.Introduction and objectives: Acute myocarditis is an inflammatory disease of the myocardiumdue to a viral infection in majority ofcases. Diagnosis is performed by obtaining anendomyocardial biopsy (BEM), however it is an invasive technique; its use is not very common in pediatrics. The disease usually resolves itself spontaneously, but some patients may die or have severe ventricular dysfunction, which requires a heart transplant. No treatment has demonstrated to improve the prognosis yet. The aim of this study is to check the characteristics of a series of pediatric patients with acute myocarditis, describe their outcome, the criteria of poor prognosis and the usefulness and risks of different diagnostic techniques, such as BEM. We will describe the usefulness of antiviral and immunosuppressive treatment in a selected population of patients. Material and methods: We reviewed all cases of persons under the age of 18 who had been admitted to Vall d'Hebron Hospital with the diagnosis of acute myocarditis between April 2007 and September 2018. We reviewed clinical and demographic characteristics, diagnostic tests as well as the usefulness of the BEM in this population. Immunohistochemical results of BEM were compared with those observed in a patient population with inheritedcardiomyopathy. The effectiveness of medical treatment was studied by comparing the outcome of treated patients with that of a historical cohort of similar characteristics that did not receive any specific treatment. Results:41 patients (25 men, 16 women, median age 25 months) presented 42 episodes of myocarditis. The diagnosis was performed by BEM in 14/42 cases (33.3%), magnetic resonance in 27/42 (64.3%) and through clinical presentation in 1/42 patient (2.4%). With a median follow-up of 47 months (between 7 and 140 months), a complete resolution of the situation with normalization of left ventricular ejection fraction (LVEF) and left ventricular end diastolic volume (LVEDD) occurred in 33/42 cases (78.5%). The most frequently implicated virus was PVB19 (9/42 cases, 21.4%) followed by enterovirus (5/42 cases, 11.9%). Four patients died (9.7%) and 5/41 (12.2%) required a heart transplant. In the univariate analysis, the factors that were associated with a poor outcome (death or transplant) were the need for ECMO at admission (p = 0.041), LVEF less than 35% (p = 0.02) and right ventricular dysfunction (p = 0.02). In the multivariate analysis, only the LVEF had statistical significance (p = 0.007). Regarding the anatomopathological findings, it was observed that no data were specific for acute myocarditis and that 3/5 patients (60%) with genetic cardiomyopathy met the immunohistological criteria of myocarditis. From February 2015 the patients with the most severe illness were treated with immunosuppression or antiviral treatment based on the anatomopathologicalresults and the viral PCR in the BEM. A total of 9 patients were treated and their outcomewas compared with a historical cohort of 11 patients with similar characteristics. Transplant-free survival at one year was 100% in the treated group vs. 63% (p = 0.042). In the long term, 8/9 treated patients were able to fully recover in comparison to 6/11 patients of the other group who received standard treatment (88.9% vs. 54.5%, p = 0.095) Conclusions: LVEF <35% is the only risk factor associated with a higher mortality or a higher risk of transplantation. BEM is a safe and useful diagnostic tool in the pediatric population with acute myocarditis. The specific treatment based on the results of the BEM improves LVEF and the outcome of patients in the short term