ABSTRACT ST-segment elevation myocardial infarction is one of the cardiovascular diseases with the highest mortality. Its prognosis is related to the probability of developing short- or long-term complications and depends more on conditions at admission than on previous coronary risk factors. Studies aimed at developing a formula to quantify the risk of death or complications in patients with acute myocardial infarction using either a rating or a score date back to the 1950s. Differences in the applicability of these risk stratification scores within the Cuban population are due to the fact that they were developed in high-income countries and, therefore, their extrapolation is questionable. Sociodemographic, ethnic, genetic and idiosyncratic differences may prevent the results predicted in the original studies from being accurately reproduced in different populations.

RESUMEN El infarto agudo de miocardio con elevación del segmento ST es una de las enfermedades cardiovasculares con mayor mortalidad. Su pronóstico se relaciona con la probabilidad de desarrollar complicaciones a corto o largo plazo y depende más de las condiciones al ingreso que de los factores de riesgo coronario previos. Los estudios encaminados a desarrollar una fórmula que permita cuantificar riesgo de muerte o complicaciones de un paciente con infarto agudo de miocardio, mediante una puntuación o score, se remontan a la década de 1950. Las diferencias en la aplicabilidad de estas escalas de estratificación de riesgo existentes, a la población cubana, derivan del hecho de haber sido desarrolladas en países de ingresos altos, por lo cual su extrapolación es cuestionable. Existen diferencias sociodemográficas, étnicas, genéticas e idiosincráticas, que pueden ser la causa de que los resultados predichos en los estudios originales no sean reproducibles con exactitud en poblaciones diferentes.

ABSTRACT Introduction: The frequency of non-ST elevation acute myocardial infarction is on the increase, and so is the number of adverse results in patients with acute ischemic coronary disease. Objective: Identify the electrocardiographic variables associated to the occurrence of adverse cardiovascular events in non-ST elevation acute myocardial infarction. Method: A cross-sectional correlational study was conducted of 68 patients with non-ST elevation acute myocardial infarction cared for at Arnaldo Milián Castro Hospital in the province of Villa Clara. Attention was paid to electrocardiographic findings and adverse cardiac events occurring during the hospital stay. Bivariate analyses were performed to establish the relationship between the two variables, using the chi square statigram and relative risk estimation. Results: The most common electrocardiographic findings were T-wave inversion (≥ 2 mm), ST depression and long corrected QT by Bazzet's formula. Of the total study subjects 26.5% had adverse cardiovascular events. ST depression, long corrected QT and ST elevation in aVR were significantly associated to in-hospital adverse events (p < 0.05). Conclusions: Association of ST depression, ST elevation in aVR and long corrected QT with the occurrence of adverse in-hospital cardiovascular events suggests that these findings may be taken into account as possible indicators of an unfavorable evolution in patients with non-ST elevation acute myocardial infarction.

RESUMEN Introducción: La frecuencia de infarto agudo de miocardio sin elevación del segmento ST se está incrementando y, con ella, los resultados adversos en pacientes con enfermedad coronaria isquémica aguda. Objetivo: Identificar las variables electrocardiográficas asociadas a la aparición de eventos cardiovasculares adversos en el infarto agudo de miocardio sin elevación del segmento ST. Método: Se realizó un estudio transversal, de tipo correlacional, con 68 pacientes con infarto agudo de miocardio sin elevación del segmento ST atendidos en el Hospital “Arnaldo Milián Castro”, en la provincia de Villa Clara. Se estudiaron los hallazgos electrocardiográficos y eventos cardiacos adversos durante el ingreso. Se hicieron análisis bivariados para establecer la relación de ambas variables, utilizando el estadígrafo chi cuadrado y el riesgo relativo. Resultados: Los hallazgos electrocardiográficos más frecuentes fueron la inversión de la onda T (≥ 2mm), depresión del segmento ST y el QT corregido largo mediante la fórmula de Bazzet. El 26,5 % presentaron eventos cardiovasculares adversos. La depresión del segmento ST, el QT largo corregido y la elevación del segmento ST en aVR se asociaron significativamente con eventos adversos intrahospitalarios (p < 0,05). Conclusiones: La asociación de la depresión del segmento ST, la elevación del segmento ST en aVR y el QT largo corregido con la ocurrencia de eventos cardiovasculares adversos intrahospitalarios, sugiere que estos hallazgos se pueden tener en cuenta como posibles indicadores de evolución desfavorable en pacientes con infarto agudo de miocardio sin elevación del segmento ST.

ABSTRACT Introduction: Controversies still persist regarding the events of cardiovascular morphogenesis and an almost total absence of morphometric parameters in the initial phases of its development. Objectives: To determine the non-compacted to compacted (NC/C) myocardium ratio in both ventricles and the chronological progression of this ratio in the period studied. Method: A descriptive, cross-sectional study was carried out with 18 human embryos belonging to the Embryoteca of the Universidad de Ciencias Médicas de Villa Clara (Cuba) classified between Carnegie stages 17 and 23. The NC/C ratio -which is simply the mathematical calculation of the ratio between the non-compacted and compacted portions per specimen and per stage- was determined. Results: The application of this ratio in the right ventricle of the embryos obtained the following results: 7.17; 4.26; 3.12; 2.79; 2.36; 2.84 and 2.10 in Carnegie's stages 17, 18, 19, 20, 21, 22 and 23, respectively. In these same specimens, the left ventricle yielded the following results: 5.0; 3.80; 2.68; 2.18; 2.50; 2.01 and 1.56, also organized by stages. Conclusions: NC/C ratios obtained quantitatively support a progression of the ventricular myocardial compaction in the evaluated stages; their higher values at the apex denote that it may still be incomplete in this zone.

RESUMEN Introducción: Aún persisten controversias en los eventos de la morfogénesis cardiovascular y una ausencia, casi total, de parámetros morfométricos en las fases iniciales de su desarrollo. Objetivos: Determinar la razón miocardio no compactado/miocardio compactado (NC/C) en ambos ventrículos y la evolución cronológica de esta razón en el período estudiado. Método: Se realizó un estudio descriptivo, transversal, con 18 embriones humanos pertenecientes a la Embrioteca de la Universidad de Ciencias Médicas de Villa Clara (Cuba) clasificados entre los estadios 17 y 23 de Carnegie. Se determinó el índice NC/C, el cual no es más que el cálculo matemático de la razón entre las porciones no compactada y compactada por espécimen y por estadios. Resultados: Los resultados de la aplicación de este índice en el ventrículo derecho de los embriones son: 7,17; 4,26; 3,12; 2,79; 2,36; 2,84 y 2,10 en los estadios de Carnegie 17, 18, 19, 20, 21, 22 y 23, respectivamente. En estos mismos especímenes se obtuvo como resultado en el ventrículo izquierdo: 5,0; 3,80; 2,68; 2,18; 2,50; 2,01 y 1,56, igualmente organizado por estadios. Conclusiones: Los índices NC/C obtenidos sustentan cuantitativamente que la compactación del miocardio ventricular avanza en los estadios evaluados; sus valores, mayores en el vértice, denotan que es posible que aún no haya concluido en esta zona.

ABSTRACT Introduction: Although some studies relate P wave parameters to different atrial conduction times, they do not consider each electrocardiogram lead separately. Objective: To determine the duration of P wave (Pdur) in the 12 leads of the electrocardiogram and relate it to the interatrial conduction time. Method: We conducted a cross-sectional study in 153 adult patients with confirmed diagnosis of atrioventricular nodal reentry tachycardia (AVNRT) or accessory pathways by invasive electrophysiological study. Results: When comparing the Pdur between arrhythmic substrates by each lead, no significant differences were found, except for V6. In leads II, III, aVR, aVF, V1 and V3-V6, Pdur was correlated with the interatrial conduction time in both arrhythmic substrates. In our multivariate analysis, the Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile in inferior wall leads and in V3, V5 and V6. High values of the area under the receiver operating characteristic curve were observed in II (0.950; p<0.001), III (0.850; p<0.001) and V5 (0.891; p<0.001) leads. Conclusions: The Pdur showed no difference by leads when comparing cases with AVNRT and accessory pathways, except for V6. Most of the leads were correlated with the interatrial conduction time; Pdur was an independent predictor of interatrial conduction times ≥ 95 percentile. Lead II has the greatest discriminatory ability to find prolonged values of interatrial conduction time.

RESUMEN Introducción: Existen algunos estudios que relacionan parámetros de la onda P con diferentes tiempos de conducción auricular, pero no se han realizado teniendo en cuenta a cada derivación del electrocardiograma. Objetivo: Determinar la duración de la onda P (Pdur) en las 12 derivaciones y relacionarlas con el tiempo de conducción interauricular. Método: Estudio de corte transversal en 153 pacientes adultos con diagnóstico confirmado de taquicardia por reentrada intranodal (TRIN) o vías accesorias mediante estudio electrofisiológico invasivo. Resultados: Al comparar la Pdur entre sustratos arrítmicos por cada derivación, no existieron diferencias significativas, excepto en V6. En las derivaciones DII, DIII, aVR, aVF, V1 y de V3-V6 la Pdur se correlacionó con el tiempo de conducción interauricular en ambos sustratos arrítmicos. En el análisis multivariado, la Pdur constituyó un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil, en las derivaciones de cara inferior y en V3, V5 y V6. Se observaron altos valores del área bajo la curva de la Característica Operativa del Receptor en las derivaciones DII (0,950; p<0,001), DIII (0,850; p<0,001) y V5 (0,891; p<0,001). Conclusiones: No existen diferencias por derivación en la Pdur al comparar casos con TRIN y vías accesorias, excepto en V6. La mayoría de las derivaciones se correlacionaron con el tiempo de conducción interauricular. La Pdur fue un predictor independiente de tiempos de conducción interauricular ≥ 95 percentil. La derivación DII presenta la mayor capacidad discriminativa para encontrar valores prolongados del tiempo de conducción interauricular.

Abstract INTRODUCTION The scales available to predict death and complications after acute coronary syndrome include angiographic studies and serum biomarkers that are not within reach of services with limited resources. Such services need specific and sensitive instruments to evaluate risk using accessible resources and information. OBJECTIVE Develop a scale to estimate and stratify the risk of intrahospital death in patients with acute ST-segment elevation myocardial infarction. METHODS An analytical observational study was conducted in a universe of 769 patients with acute ST-segment elevation myocardial infarction who were admitted consecutively to the Camilo Cienfuegos Provincial Hospital in Sancti Spíritus Province, Cuba, from January 2013 to March 2018. The final study cohort included 667 patients, excluding 102 due to branch blocks, atrial fibrillation, drugs that prolong the QT interval, low life expectancy or history of myocardial infarction. The demographic variables of age, sex, skin color, classic cardiovascular risk factors, blood pressure, heart rate, blood glucose level, in addition to duration and dispersion of the QT interval with and without correction, left ventricular ejection fraction, and glomerular filtration rate were included in the analysis. Patients were categorized according to the Killip-Kimball Classification for degree of heart failure. A risk scale was constructed, the predictive ability of which was evaluated using the detectability index associated with an receiver-operator curve. RESULTS Seventy-seven patients died (11.5%). Mean blood glucose levels were higher among the deceased, while their systolic and diastolic blood pressure, left ventricular ejection fraction, and glomerular filtration rate were lower than those participants discharged alive. Relevant variables included in the scale were systolic blood pressure, Killip-Kimball class, cardiorespiratory arrest, glomerular filtration rate, corrected QT interval dispersion, left ventricular ejection fraction, and blood glucose levels. The variable with the best predictive ability was cardiorespiratory arrest, followed by a blood glucose level higher than 11.1 mmol/L. The scale demonstrated a great predictive ability with a detectability index of 0.92. CONCLUSIONS The numeric scale we designed estimates and stratifies risk of death during hospitalization for patients with ST-segment elevation myocardial infarction and has good metric properties for predictive ability and calibration.

ABSTRACT Wolff-Parkinson-White syndrome is a rare and non-structural heart disease, which belongs to the ventricular preexcitation syndromes. It is associated with the development of sudden death, as it can induce the appearance of malignant arrhythmias in the patient and its diagnosis can be established through electrocardiogram. If it takes place in people linked to sport, with the development of intense physical exercise, it can increase the risk of sudden death. The case of a high-performance athlete with a diagnosis of Wolff-Parkinson-White syndrome is described, and the guidelines to be followed according to international criteria for the interpretation of the electrocardiogram in sportsmen and women are presented.

RESUMEN El síndrome de Wolff-Parkinson-White es una cardiopatía no estructural poco frecuente que pertenece a los denominados síndromes de preexcitación ventricular. Está asociada al desarrollo de muerte súbita, pues puede inducir a la aparición de arritmias malignas y su diagnóstico puede establecerse a través de la realización de un electrocardiograma. En caso de presentarse en personas vinculadas a la práctica deportiva, con el desarrollo de ejercicio físico intenso, puede incrementar el riesgo de muerte súbita. Se describe el caso de un atleta de alto rendimiento con diagnóstico de síndrome de Wolf Parkinson White y se presentan las pautas a seguir, según los criterios internacionales para la interpretación del electrocardiograma en deportistas.

ABSTRACT Introduction: Despite their indisputable benefits for the quality of life and life expectancy of patients with precise pacemaker indications, a number of these devices have shown to have deleterious effects in terms of left ventricular function and geometry. Objective: Identify echocardiographic changes in patients with permanent cardiac stimulation applied from the right ventricular tip. Methods: A prospective longitudinal descriptive study was conducted of 84 patients requiring permanent pacemaker implantation with stimulation from the right ventricular tip. Echocardiographic data were collected before and after implantation. Results: Of the total patients, 53.65% were male. Mean age was 68.25 years. An increase was observed in all the means of echocardiographic values except for the left ventricular ejection fraction, which decreased. The sequential stimulation group presented 4 more cases with grade II diastolic dysfunction than at baseline, whereas the group with non-sequential stimulation included 5 grade III diastolic dysfunction cases. Left ventricular ejection fraction lowered 6% in patients with sequential stimulation and 9% in patients with non-sequential stimulation. Conclusions: Echocardiographic changes during the study showed a group tendency to increase, except for the left ventricular ejection fraction, which decreased.

RESUMEN Introducción: A pesar de los indiscutibles beneficios en cuanto a calidad y expectativa de vida en los pacientes con indicaciones precisas de marcapasos, existen un grupo de ellos con efectos deletéreos en la función y geometría ventricular izquierda. Objetivo: Identificar modificaciones ecocardiográficas en pacientes con estimulación cardíaca permanente realizada desde punta de ventrículo derecho. Métodos: Se realizó estudio descriptivo longitudinal prospectivo a 84 pacientes que requirieron implantación de marcapasos permanente con estimulación desde punta del ventrículo derecho. Se recolectaron datos ecocardiográficos antes y después del implante. Resultados: El 53,65 % fueron del sexo masculino, edad media 68,25. Las medias de las variables ecocardiográficas incrementaron sus valores, excepto, la fracción de eyección del ventrículo izquierdo que disminuyó, el grupo con estimulación secuencial presentó 4 casos más con disfunción diastólica grado II que al inicio, el grupo con estimulación no secuencial tuvo 5 casos con disfunción diastólica grado III, la fracción de eyección del ventrículo izquierdo disminuye un 6 % en pacientes con estimulación secuencial y 9 % para el modo no secuencial. Conclusiones: Las modificaciones ecocardiográficas durante el estudio mostraron una tendencia grupal al aumento excepto la fracción de eyección del ventrículo izquierdo que disminuyó.

Resumen Objetivo: Caracterizar el Tpico-Tfinal, la dispersión del Tpico-Tfinal y el Tpico-Tfinal/QT en niños y su relación con variables clínicas. Métodos: Estudio transversal en 126 niños entre 9 y 12 años de la escuela Camilo Cienfuegos en Santa Clara, Cuba. Se obtuvieron variables clínicas y antropométricas para determinar su relación con los parámetros electrocardiográficos: el Tpico-Tfinal V5, la dispersión del Tpico-Tfinal y el Tpico-Tfinal/QT V5. Además, se realizaron pruebas de laboratorio. Resultados: La edad y la presión arterial sistólica se asocian con una mayor probabilidad de tener valores del Tpico-Tfinal/QT V5 ≥75 percentil para ambos sexos (OR: 1.72, IC 95%: 1.02-2.91; p= 0.043), (OR: 1.08, IC 95%: 1.01-1.16; p= 0.017) respectivamente. El índice de masa corporal y la presión arterial sistólica están correlacionados de manera lineal y significativa con el Tpico-Tfinal/QT V5 (r= 0.224; p= 0.012) y (r= 0.220; p= 0.014) respectivamente. Conclusiones: La edad de los pacientes y las cifras de presión arterial sistólica son factores que aumentan la probabilidad de tener valores del percentil Tpico-Tfinal/QT V5 ≥75. Existe correlación lineal significativa entre el Tpico-Tfinal/QT V5 con el índice de masa corporal y la presión arterial sistólica.

Abstract Aim: To characterize the Tpeak-Tend, the Tpeak-Tend dispersion and Tpeak-Tend/QT in children and its relationship with clinical variables. Methods: Cross-sectional study in 126 children between 9 and 12 years of the Camilo Cienfuegos School in Santa Clara, Cuba. Clinical and anthropometric variables were obtained to determine their relationship with electrocardiographic parameters: Tpeak-Tend V5, Tpeak-Tend dispersion and Tpeak-Tend/QT ratio V5. In addition, laboratory tests were conducted. Results: Age and systolic blood pressure are associated with an increased probability of having values of Tpeak-Tend/QT V5 ≥75 percentile for both sexes (OR: 1.72, CI 95%: 1.02-2.91; p= 0.043), (OR: 1.08, CI 95%: 1.01-1.16; p= 0.017) respectively. The body mass index and systolic blood pressure are linearly and significantly correlated with the Tpeak-Tend/QT V5 (r= 0.224; p= 0.012) and (r= 0.220; p= 0.014) respectively. Conclusions: The age of the patients and the systolic blood pressure figures are factors that increase the probability of having values of the Tpeak-Tend/QT V5 ≥75 percentile. There was a significant linear correlation between the Tpeak-Tend/QT V5 with the body mass index and the systolic blood pressure.

ABSTRACT At the end of the 1990s, off-pump myocardial revascularization surgery gained momentum. Hence, a number of cardiac surgery centers adopted it as the most frequent surgical procedure to reduce complications. To implement it, the many medical equipment companies provided the surgical community with retractable stabilizers to facilitate cardiac positioning by suction and pressure, especially for lateral and posterior wall revascularization and coronary segment stabilization. These devices have been shown to be safe and effective; however, the patient presented is a rare case, in which epicardial dissection occurred secondary to the use of stabilizers. Although complex, this complication was eventually resolved with an endomyocardial circular pericardial patch technique and ventricular repair. The patient had a satisfactory outcome.

RESUMEN A finales de la década de los '90, la cirugía de revascularización miocárdica sin circulación extracorpórea tomó gran auge, por lo que -en muchos centros de cirugía cardíaca- pasó a ocupar la manera más frecuente de realizarla, en aras de reducir sus complicaciones. Para ejecutarla, las diferentes firmas de fabricantes de equipos médicos pusieron a disposición de la comunidad quirúrgica estabilizadores retráctiles para facilitar el posicionamiento cardíaco por succión y presión, para revascularizar, sobre todo, los sectores lateral y posterior; además, para la estabilización del segmento coronario. Estos dispositivos han mostrado seguridad y eficacia; sin embargo, el paciente que se presenta constituye un caso aislado, donde se produjo disección epicárdica secundaria al uso de estabilizadores. A pesar de su complejidad, esta complicación pudo ser solucionada con técnica de parche pericárdico circular endomiocárdico y reparación ventricular, y el paciente tuvo una evolución satisfactoria.

ABSTRACT INTRODUCTION Hypertension is one of the most studied risk factors for cardiovascular disease in adults; in children and adolescents, its global prevalence changes with age, from 1%-3% in children to 3.2% in adolescents. In adults, in addition to hypertension, several biochemical markers of cardiovascular risk have been identified. Confirming an association between these and hypertension in childhood and adolescence would allow for more timely diagnosis and monitoring of cardiovascular disease, since the presence of both the markers and hypertension would imply increased risk. OBJECTIVE Confirm an association between biochemical risk markers of cardiovascular disease and hypertension in children aged 8 to 11 years. METHODS A cross-sectional study of 373 children aged 8-11 years was conducted in 3 primary schools in the city of Santa Clara in central Cuba. The variables examined were age, sex, height, blood pressure, cholesterol, triglycerides, lipoproteins and apolipoproteins. The children were classified as normotensive, prehypertensive or hypertensive, based on blood pressure readings and percentiles for age, sex and height. Descriptive statistics were calculated for quantitative variables. A bivariate analysis, tests of independence for qualitative variables and a means comparison for quantitative variables (ANOVA and its nonparametric alternative, the Kruskal Wallis test) were performed. Fisher’s F-test and its associated probability value were employed. RESULTS Some 32.2% of the children were prehypertensive and 5.1% hypertensive. Cholesterol and triglyceride values were significantly higher in hypertensive than in normotensive children (p = 0.028 and p = 0.047, respectively). HDL numbers were higher in normotensive children (p = 0.001), and LDL numbers and the LDL/ HDL ratio were higher in the hypertensive children, with differences between groups (p = 0.001 for both variables). There were differences between the three blood pressure categories for lipoprotein(a) and ApoA (p <0.001 and p = 0.001), for ApoB and for the ApoB/ApoA ratio (p <0.001 for both variables), with lower ApoA values and higher ApoB and ApoB/ApoA values in the hypertensive children. CONCLUSIONS The biochemical risk markers most strongly associated with hypertension in children are ApoB values, LDL, lipoprotein(a), and LDL/HDL and ApoB/ApoA ratios.

ABSTRACT INTRODUCTION Many clinical settings lack the necessary resources to complete angiographic studies, which are commonly used to predict complications and death following acute coronary syndrome. Corrected QT-interval dispersion can be useful for assessing risk of myocardial infarction recurrence. OBJECTIVE Evaluate the relationship between corrected QT-interval dispersion and recurrence of myocardial infarction in patients with ST- segment elevation. METHODS We conducted a prospective observational study of 522 patients with ST-segment elevation myocardial infarction admitted consecutively to the Camilo Cienfuegos General Provincial Hospital in Sancti Spiritus, Cuba, from January 2014 through June 2017. Of these, 476 were studied and 46 were excluded because they had other disorders. Demographic variables and classic cardiovascular risk factors were included. Blood pressure, heart rate, blood glucose, and corrected and un- corrected QT-interval duration and dispersion were measured. Patients were categorized according to the Killip-Kimball classification. Association between dispersion of the corrected QT-interval and recurrence of infarction was analyzed using a binary logistic regression model, a regression tree and receiver operator characteristic curves. RESULTS Patients with recurrent infarction (56; 11.8%) had higher average initial blood glucose values than those who did not have recurrence; the opposite occurred for systolic and diastolic blood pressure and for left ventricular ejection fraction. Dispersion of the corrected QT-interval was a good predictor of infarction recurrence according to a multivariate analysis (OR = 3.09; 95% CI = 1.105–8.641; p = 0.032). Cardiac arrest is the variable that best predicts recurrence. No recurrence of infarction occurred in 97% of patients without cardiac arrest, left ventricular ejection fraction >45% and corrected QT- interval dispersion <80 ms. CONCLUSIONS Risk of infarction recurrence is low in patients without cardiac arrest, with left ventricular ejection fraction >45% and with dispersion of corrected QT-interval <80 ms. Patients with corrected QT-interval dispersion ≥80 ms have greater risk of recurrence of infarction, which suggests that this variable could be used for stratification of risk following ST-segment elevation myocardial infarction.