Associated factors with the occurrence of in-hospital cardiac arrest in patients admitted to internal medicine wards for non-cardiovascular causes. / Factores asociados a la ocurrencia de paro cardiaco intrahospitalario en pacientes ingresados en salas de medicina interna por causas no cardiovasculares.

BACKGROUND AND OBJECTIVE: In-hospital cardiac arrest (IHCA) has a low survival rate, so it is essential to recognize the cases with the highest probability of developing it. The aim of this study is to identify factors associated with the occurrence of IHCA. MATERIAL AND METHODS: A single-center case-control study was conducted including 65 patients admitted to internal medicine wards for non-cardiovascular causes who experienced IHCA, matched with 210 admitted controls who did not present with IHCA. RESULTS: The main reason for admission was pneumonia. The most prevalent comorbidity was arterial hypertension. Four characteristics were strongly and independently associated with IHCA presentation, these are electrical left ventricular hypertrophy (LVH) (OR: 13.8; 95% IC: 4.7-40.7), atrial fibrillation (OR: 9.4: 95% CI: 4.3-20.6), the use of drugs with known risk of torsades de pointes (OR: 2.7; 95% CI: 1.3-5.5) and the combination of the categories known risk plus conditional risk (OR: 17.1; 95% CI: 6.7-50.1). The first two detected in the electrocardiogram taken at the time of admission. CONCLUSION: In admitted patients for non-cardiovascular causes, the use of drugs with a known risk of torsades de pointes, as well as the detection of electrical LVH and atrial fibrillation in the initial electrocardiogram, is independently associated with a higher probability of suffering a IHCA.

Would a complete electrophysiological study allow us to make a correct diagnosis? Case report.

BACKGROUND: Oblique course of some left accessory pathways is rare An incomplete electrophysiological study may confuse us between an oblique accessory pathway or the presence of two accessory pathways. The proximity of all atrial and ventricular electrograms, at each pole of the catheter, within the coronary sinus may be a novel finding. CASE PRESENTATION: A 68-year-old woman patient presented arrhythmias with hypotension requiring electrical cardioversion. Her electrocardiogram (ECG) was interpreted as atrial fibrillation by accessory pathway. We performed with the protocol of ablation stablished in our laboratory: two punctures on the right femoral vein with placement of introducers (8F and 7F) by Seldigner technique and one puncture on the left femoral vein (7F). The study was performed with BIOTRONIK technology (Multicath study catheter), a non-deflectable 7F quadripolar catheter with 2 mm tip electrode to record the His electrogram, a non-deflectable decapolar catheter with 5 pairs of coronary sinus (CS) electrodes. Accessory pathway mapping was performed in right and left cavities and within the CS. All electrograms into CS showed short AV from proximal to distal CS. Finally, ablation of two accessory pathway recordings was achieved at two distant epicardial points within the CS. CONCLUSIONS: Ablation at two distant sites, one on the ventricular side and the other on the mitral annulus, suggests the presence of an oblique accessory pathway and at the same time the differential diagnosis of the presence of two accessory pathways. In our point of view according the above, we consider this is a very rare case of oblique AP with epicardial trajectory. The sequence of electrograms (in this case) along the CS has not been seen before in the literature reviewed. It is important, regardless of the urgency, to follow diagnostic and therapeutic protocols in invasive electrophysiology.

El "vetusto" electrocardiograma sigue aportando nuevas variables para la asistencia y educación médicas / The "old" electrocardiogram continues to provide new variables for medical care and education

El descubrimiento de la electrocardiografía marcó un hito para la medicina: ofreció una mejor comprensión de la fisiología cardiovascular, es una herramienta imprescindible para el diagnóstico, evaluación y estratificación pronóstica de casi la totalidad de las enfermedades cardiovasculares, y ha sido un componente insustituible de las investigaciones cardiológicas de la medicina contemporánea. Importantes investigaciones de la cátedra de Cardiología del Hospital Universitario Cardiocentro "Ernesto Guevara" la han tenido como objeto de estudio en consonancia con las directrices del sistema de salud, para su aplicación en la asistencia y la actualización de los programas de la especialidad, los que se han enriquecido con nuevas variables electrocardiográficas denominadas como "no clásicas". Es objetivo de los autores comunicar algunos resultados científicos novedosos de investigaciones relacionadas con este vetusto medio de diagnóstico, los que han sido publicadas en revistas de alto impacto.

The discovery of electrocardiography marked a milestone for medicine: it offered a better understanding of cardiovascular physiology and has been an essential tool for the diagnosis, evaluation, and prognostic stratification of almost all cardiovascular diseases, and it has been an irreplaceable component of cardiology research in contemporary medicine. Important investigations of the Cardiology professorship of the "Ernesto Guevara" University Hospital have had it as an object of study in line with the guidelines of the health system, for its application in assistance and updating of specialty programs, which have been enriched with new electrocardiographic variables called "non-classical". It is the objective of the authors to communicate some novel scientific results of investigations related to this ancient aid of diagnosis, which have been published in high-impact journals.

Uneven vectorial projection is the best explanation for QRS dispersion, not the asynchronic ventricular activation.

BACKGROUND: It is believed that QRS dispersion (QRSd) is caused by asynchrony of ventricular activation, but there are no studies that prove it. OBJECTIVES: To determine the mechanism that best explains QRSd in surface electrocardiogram (ECG). METHODS: Cross-sectional study in 95 consecutive patients (median age: 31.0 years [25-52], female sex: 66.3%) with atrioventricular nodal reentrant tachycardia. All 12 ECG leads were recorded at once, simultaneously with the intracardiac recordings. QRSd was quantified as the difference between maximum (QRSmax) and minimum QRS duration (QRSmin). QRS was measured firstly at a calibration of 20 mm/mV and a sweep speed of 50 mm/s, enhancement 10× (basic measurement [BM]), and after at sweep speed of 150 mm/s, enhancement 80 - 160×. The interventricular dyssynchrony (IVD) was also quantified. RESULTS: QRSmax increased from BM (98 ms [91-103]) to 80× (102 ms [99-108]; p = 0.029) and 160× (104 ms [101.5-110]; p = 0.027). QRSmin, almost equaled the duration of QRSmax at 160× (103 ms [100-108]). With BM, QRSd was 26 ms [22-35] and was reduced 26-fold (p < 0.001) by magnifying the QRS at 160× (1 ms [0-3]). IVD was weakly correlated with QRSd (r = 0.234, p = 0.023), but strongly with the total QRS at 160× (r = 0.676, p < 0.001). CONCLUSION: When QRS complex is narrow, the best explanation for the origin of QRSd on the surface ECG is the unequal projection of the ventricular depolarization vector in the different axis of the leads.

Ventricular arrhythmias are associated with increased QT interval and QRS dispersion in patients with ST-elevation myocardial infarction.

INTRODUCTION AND OBJECTIVES: The electrocardiogram continues to be essential in the diagnosis of acute myocardial infarction, and a useful tool in arrhythmic risk stratification. We aimed to determine which electrocardiographic variables can successfully predict the occurrence of ventricular arrhythmias (VA) in patients following ST-segment elevation myocardial infarction (STEMI). METHODS: We performed an observational study including 667 patients with STEMI admitted to the University Hospital in Sancti Spíritus, Cuba. Demographic variables, cardiovascular risk factors, and clinical variables were recorded. Electrocardiographic variables included QT interval duration (measured and corrected) and QT dispersion, QRS duration and dispersion, JT interval duration and ST-segment elevation magnitude. We also determined left ventricular ejection fraction and glomerular filtration rate. A binary statistical regression model and a regression tree were used to determine the variables that successfully predicted VA. RESULTS: VA occurred in 92 (13.8%) patients, within the first 48 hours in 68 (73.9%) and after this period in 24 (26.1%) patients. The variables associated with VA were QT interval duration >529 ms and QT dispersion >66 ms, QRS dispersion >50 ms, and the presence of ST-segment elevation in six or more leads. CONCLUSIONS: The main predictor of VA occurring during the initial 48 hours was QT interval duration, while, after this period, it was QRS dispersion.

QRS and QT Interval Modifications in Patients with Type 2 Diabetes Mellitus.

INTRODUCTION: Diabetes Mellitus imbricates inflammatory processes on their pathophysiology, it could affect cardiac electrophysiology. Cardiac inflammatory process leads electrocardiogram changes. Nevertheless, there are discrepancies about whether it prolongs or decreases waves and intervals such as QRS and QT. Furthermore, QRS dispersion has not been studied. OBJECTIVE: To identify QRS complex and QT interval modifications in type 2 diabetic patients. METHODS: A descriptive cross-sectional study was carried out in 59 type 2 diabetic patients selected by non-probabilistic sampling. Electrocardiogram was performed, QRS and QT interval were measured manually by two observers. Dispersion of both variables was calculated to compare with normal values. RESULTS: Two variables showed differences for sex, QRS dispersion was higher in females (45.84), p=0.0001 vs. reference value; QT dispersion (63.12) showed significance difference (p=0.0246) vs. reference value for males. Greater than five years of illness was related to higher QRS values (124.11 vs. 137.28), p=0.005 and corrected QT dispersion (61.81 vs. 78.79), p=0.022. CONCLUSIONS: The electrocardiographic differences between sexes may suggest a gender influence. The longer duration of diabetes diseases could increase cardiovascular risk of arrhythmias due to greater QRS duration and corrected QT interval prolongation.

Increased QRS duration and dispersion are associated with mechanical dyssynchrony in patients with permanent right ventricular apical pacing.

BACKGROUND: Permanent right ventricular apical pacing may have negative effects on ventricular function and contribute to development of heart failure. We aimed to assess intra- and interventricular mechanical dyssynchrony in patients with permanent right ventricular apical pacing, and to establish electrocardiographic markers of dyssynchrony. METHODS: 84 patients (46:38 male:female) who required permanent pacing were studied. Pacing was done from right ventricular apex in all patients. We measured QRS duration and dispersion on standard 12-lead ECG. Intra- and interventricular mechanical dyssynchrony and left ventricular ejection fraction were assessed by transthoracic echocardiography. Patients were followed-up for 24 months.  Results: Six months after implantation, QRS duration increased from 128.02 ms to 132.40 ms, p≤0.05. At 24 months, QRS dispersion increased from 43.26 ms to 46.13 ms, p≤0.05. Intra- and interventricular dyssynchrony increased and left ventricular ejection fraction decreased during follow-up. A QRS dispersion of 47 ms predicted left ventricular dysfunction and long-term electromechanical dyssynchrony with a sensitivity of 80% and a specificity of 76%.  Conclusion: In patients with permanent right ventricular apical pacing there is an increased duration and dispersion of QRS related to dyssynchrony and decreased left ventricular ejection fraction. This study shows that QRS dispersion could be a better predictive variable than QRS duration for identifying left ventricular ejection fraction worsening in patients with permanent right ventricular apical pacing. The electrocardiogram is a simple tool for predicting systolic function worsening in these patients and can be used at the bedside for early diagnosis in the absence of clinical symptoms, allowing adjustments of medical treatment to prevent progression of heart failure and improve the patient's quality of life.

Variables asociadas a la severidad en pacientes con Covid-19 / Variables associated with severity in COVID-19 patients

En la COVID-19 un porcentaje de los enfermos desarrolla cuadros severos, con una elevada mortalidad, siendo necesario el estudio de sus características con el objetivo de frenar la progresión de la enfermedad. Se realizó un estudio retrospectivo en una cohorte de 150 pacientes adultos atendidos en el hospital Manuel Fajardo de Villa Clara, Cuba, en el período de marzo a junio de 2020. Se analizaron variables demográficas, clínicas, de laboratorio, gasométricas y radiológicas medidas al ingreso hospitalario; definiéndose dos grupos de pacientes según la evolución clínica: severos y no severos. Para la comparación de los grupos se realizó un análisis bivariado con el objetivo de determinar aquellas variables con asociación significativa a la severidad. Del total de pacientes, 26 (17,3%) evolucionaron a la severidad y 124 (83.7%), evolucionó satisfactoriamente. Los pacientes severos se caracterizaron por tener edad avanzada (media: 83 años) y presentar comorbilidades; siendo las más significativas: hipertensión arterial, diabetes mellitus, cardiopatía, enfermedad renal crónica y cáncer (p<0.0001). La polipnea y diarrea fueron las manifestaciones clínicas con mayor asociación a la severidad (p<0.0001), seguido por la fiebre (p=0.0157). La escala pronóstica quick SOFA mostró ser un instrumento útil para evaluar a los pacientes al ingreso. Las variables de laboratorio: neutrófilos, linfocitos, índice neutrófilos/linfocitos, hemoglobina. y lactato deshidrogenasa fueron las que mayor asociación tuvieron con la severidad (p<0.0001). Los leucocitos, lactato, dímero D, proteína C reactiva, glicemia y calcio también mostraron resultados significativos (p< 0.05). De las variables gasométricas, la presión y saturación arterial de oxígeno fueron las más significativamente asociadas a la severidad; así como la presencia de infiltrados o consolidación pulmonar en la radiografía de tórax (p <0.0001). El estudio permitió identificar variables al ingreso hospitalario, asociadas a progresión hacia formas severas de la enfermedad

In COVID-19, a percentage of patients develop severe disease, with high mortality, since has been necessary to study its characteristics to stop the progression of the disease. A retrospective study was carried out in a cohort of 150 adult patients attended at Manuel Fajardo Hospital in Villa Clara, Cuba, from March to June 2020. Demographic, clinical, laboratory, gasometric and radiological variables measured at hospital admission were analyzed, defining two groups of patients according to clinical evolution: severe and non-severe. For the comparison of the groups a bivariate analysis was performed, with the objective of determining those variables with a significant association to severity. Of the total number of patients, 26 (17.3%) evolved to severity and 124 (83.7%) evolved satisfactorily. Severe patients were characterized by advanced age (mean: 83 years) and comorbidities; the most significant being hypertension, diabetes mellitus, heart disease, chronic kidney disease and cancer (p< 0.0001). Polypnea and diarrhea were the clinical manifestations with the highest association with severity (p<0.0001), followed by fever (p=0.0157). The quick SOFA prognostic scale proved to be a useful instrument to evaluate patients at admission. Laboratory variables: neutrophils, lymphocytes, neutrophil/lymphocyte ratio, hemoglobin and lactate dehydrogenase were the most associated with severity (p<0.0001). Leukocytes, lactate, D-dimer, C-reactive protein, glycemia and calcium also showed significant results (p<0.05). Of the gasometric variables, arterial oxygen pressure and saturation were the most significantly associated with severity; as well as the presence of pulmonary infiltrates or consolidation in the chest X-ray (p<0.0001). The study allowed us to identify variables at hospital admission associated with progression to severe forms of the disease.

Estimación de riesgo en pacientes con infarto agudo de miocardio con elevación del segmento ST: Su realidad en Cuba

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 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.

New Parameter of the Second Half of the P-Wave, P-Wave Duration, and Atrial Conduction Times Predict Atrial Fibrillation during Electrophysiological Studies.

OBJECTIVE: Several P-wave parameters reflect atrial conduction characteristics and have been used to predict atrial fibrillation (AF). The aim of this study was to determine the relationship between maximum P-wave duration (PMax) and new P-wave parameters, with atrial conduction times (CT), and to assess their predictive value of AF during electrophysiological studies (AF-EPS). SUBJECTS AND METHODS: This was a cross-sectional study in 153 randomly selected patients aged 18-70 years, undergoing EPS. The patients were divided into 2 groups designated as no AF-EPS and AF-EPS, depending on whether AF occurred during EPS or not. Different P-wave parameters and atrial CT were compared for both study groups. Subsequently, the predictive value of the P-wave parameters and the atrial CT for AF-EPS was evaluated. RESULTS: The values of CT, PMax, and maximum Ppeak-Pend interval (Pp-eMax) were significantly higher in patients with AF-EPS. Almost all P-wave parameters were correlated with the left CT. PMax, Pp-eMax, and CT were univariate and multivariate predictors of AF-EPS. The largest ROC area was presented by interatrial CT (0.852; p < 0.001; cutoff value: ≥82.5 ms; sensitivity: 91.1%; specificity: 81.1%). Pp-eMax showed greater sensitivity (79.5%) to discriminate AF-EPS than PMax (72.7%), but the latter had better specificity (60.4% vs. 41.5%). CONCLUSIONS: Left atrial CT were directly and significantly correlated with PMax and almost all the parameters of the second half of the P-wave. CT, PMax, and Pp-eMax (new parameter) were good predictors of AF-EPS, although CT did more robustly.

Vectorial theory surpasses the local theory in explaining the origin of P-wave dispersion.

BACKGROUND: Local theory and the vectorial theory are used to explain the origin of P-wave dispersion (PWD). There are no previous studies that analyze both at the same time. OBJECTIVES: We set out to determine the implication of local and vectorial theories in the origin of PWD. METHODS: Cross-sectional study in 153 randomly selected patients aged 18-70 years, undergoing electrophysiological study. Inhomogeneous atrial conduction was evaluated by atrial electrogram dispersion in terms of duration (EGMdurdis) and morphology (EGMmorph dis). P-distal coronary sinus interval (P-DCS) was also measured. P-wave was measured twice, firstly at a calibration of 20 mm/mV and a sweep speed of 50 mm/s, enhancement 10× (basic measurement [BM]), and second time at sweep speed of 150 mm/s, enhancement 80-160× (high precision measurement [HPM]). RESULTS: PWD with BM was 48 ms [36-54 ms] while with HPM it was 4 ms [0-10 ms], p < 0.001. With BM, maximum and minimum P- wave duration presented a moderate correlation (r = 0.342; p < 0.001), using HPM it becomes strong (r = 0.750; p < 0.001). In cases with P-DCS < 80 ms (r = 0.965; p < 0.001), but not with P-DCS ≥ 80 ms (r = 0.649; p < 0.001), the previous correlation became almost perfect with HPM. EGMdurdis and EGMmorphdis were weak but significantly correlated with PWD. This correlation became moderate in patients with P-DCS ≥ 80 ms and disappeared in those with P-DCS, using BM and HPM. CONCLUSION: Vectorial theory explains almost entirely the PWD phenomenon. Inhomogeneous conduction could be an additional mechanism to explain PWD, but its contribution is small.

Atrial conduction explains the occurrence of the P-wave dispersion phenomenon, but weakly.

BACKGROUND: P-wave dispersion (PWD) is believed to be caused by inhomogeneous atrial conduction. This statement, however, is based on limited little solid evidence. The aim of this study was to determine the relationship between atrial conduction and PWD by means of invasive electrophysiological studies. METHODS: Cross-sectional study in 153 patients with accessory pathways and atrioventricular node reentry tachycardia (AVNRT) undergoing an electrophysiological study. Different atrial conduction times were measured and correlated with PWD. RESULTS: Only the interatrial (P-DCS) and left intra-atrial conduction times (ΔDCS-PCS) showed a significant correlation with PWD, but this correlation was weak. Multivariate linear regression analysis determined that both P-DCS (ß = 0.242; P = .008) and ΔDCS-PCS (ß = 0.295; P < .001) are independent predictors of PWD. Performing the multivariate analysis for arrhythmic substrates, it is observed that only ΔDCS-PCS continued to be an independent predictor of PWD. Analysis of the receiver operating characteristic curves showed that regardless of the types of arrhythmic substrates, PWD discriminates significantly, but moderately, to patients with P-DCS and ΔDCS-PCS ≥75 percentile. CONCLUSIONS: Interatrial and intraleft atrial conduction times were directly and significantly correlated with PWD, but only weakly, and were independent predictors of PWD. In general, PWD correctly discriminates patients with high values in interatrial and intraleft atrial conduction times, but moderately. This is maintained in cases with accessory pathways; however, in patients with AVNRT it only does so for intraleft atrial conduction times. Interatrial and intraleft atrial conduction times weakly explains PWD.

Variables electrocardiográficas asociadas a la aparición de eventos cardiovasculares adversos en el infarto agudo de miocardio sin elevación del segmento ST / Electrocardiographic variables associated to the occurrence of adverse cardiovascular events in non-ST elevation acute myocardial infarction

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 (#8805; 2mm), depresión del segmento ST y el QT corregido largo mediante la fórmula de Bazzet. El 26,5 por ciento 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 lt; 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(AU)

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 (#8805; 2 mm), ST depression and long corrected QT by Bazzet's formula. Of the total study subjects 26.5 percent 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(AU)

Índice de compactación cardíaca calculado en embriones humanos de los estadios 17 al 23 de Carnegie / Cardiac compaction index calculated in human embryos of Carnegie stages 17-23

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: 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.

Duración de la onda P en las 12 derivaciones del electrocardiograma y su relación con el tiempo de conducción interauricular en pacientes con taquicardias paroxísticas supraventriculares / P wave duration in the 12 leads of the electrocardiogram and its relationship with interatrial conduction time in patients with paroxysmal supraventricular tachycardias

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: 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.

Prognostic Scale to Stratify Risk of Intrahospital Death in Patients with Acute Myocardial Infarction with ST-Segment Elevation.

INTRODUCTION The scales available to predict death and complica-tions after acute coronary syndrome include angiographic studies and serum biomarkers that are not within reach of services with limited resources. Such services need specifi c and sensitive instruments to evaluate risk using accessible resources and information. OBJECTIVE Develop a scale to estimate and stratify the risk of intra-hospital 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 fi nal study cohort included 667 patients, ex-cluding 102 due to branch blocks, atrial fi brillation, drugs that prolong the QT interval, low life expectancy or history of myocardial infarction. The demographic variables of age, sex, skin color, classic cardiovas-cular 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 fi ltration rate were included in the analysis. Patients were categorized according to the Killip-Kimball Classifi cation 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 dia-stolic blood pressure, left ventricular ejection fraction, and glomerular fi ltration rate were lower than those participants discharged alive. Rel-evant variables included in the scale were systolic blood pressure, Killip-Kimball class, cardiorespiratory arrest, glomerular fi ltration 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 strati-fi es risk of death during hospitalization for patients with ST-segment elevation myocardial infarction and has good metric properties for predictive ability and calibration. KEYWORDS ST-segment elevation myocardial infarction, mortality, risk assessment, Cuba.