Dispersión del intervalo QT corregido como predictor de arritmias ventriculares en el infarto agudo del miocardio / Dispersion of the corrected QT interval as a predictor of ventricular arrhythmias in acute myocardial infarction

RESUMEN Fundamento: La dispersión del intervalo QT es un marcador electrocardiográfico que puede resultar útil en la estratificación de riesgo arrítmicos en pacientes con infarto agudo del miocardio. Objetivo: Describir la influencia de la dispersión del intervalo QT corregido en asociación a otros factores de riesgo como predictores de arritmias ventriculares en el infarto agudo del miocardio con elevación del segmento ST. Metodología: Se estudiaron de menera prospectiva 209 pacientes que ingresaron de forma consecutiva con diagnóstico de infarto agudo de miocardio con elevación del segmento ST de enero de 2013 a junio de 2014 en el Hospital Provincial General Camilo Cienfuegos de Sancti Spíritus. Se recogieron datos clínicos, de laboratorio electrocardiográficos y ecocardiográficos; se determinó la implicación pronóstica de la dispersión del intervalo QT corregido en la aparición de arritmias ventriculares a través de la regresión logística binaria y las curvas de operador-receptor. Resultados: Las arritmias ventriculares se presentaron en 39 (18.7 %) pacientes. La dispersión del QT corregido mostró una adecuada capacidad de discriminación en la predicción de cualquier episodio arrítmico ventricular grave (c=0.768, p=0.0001). En el análisis multivariado la dispersión del QT resultó un predictor independiente de arritmias ventriculares (OR= 7.075; IC 95%= 1.6- 32.9; p=0.009). Conclusiones: La probabilidad de presentar arritmias ventriculares durante el infarto agudo del miocardio es mayor cuando se incrementan la dispersión del intervalo QT, por lo que se sugiere debe ser una variable a evaluar en la estratificación pronostica del infarto agudo del miocardio.

ABSTRACT Background: Dispersion of the QT interval is an electrocardiographic marker that can be useful in the stratification of arrhythmic risk in patients with acute myocardial infarction. Objective: To describe the influence of corrected QT interval dispersion in association with other risk factors as predictors of ventricular arrhythmias in acute myocardial infarction with ST-segment elevation. Methodology: 209 patients who entered consecutively with diagnosis of acute myocardial infarction with elevation of the ST segment from January 2013 to June 2014 at Camilo Cienfuegos General Provincial Hospital of Sancti Spíritus were studied prospectively. Clinical, electrocardiographic and echocardiographic laboratory data were collected; the prognostic implication of the corrected QT interval dispersion in the appearance of ventricular arrhythmias through binary logistic regression and operator-receiver curves was determined. Results: Ventricular arrhythmias occurred in 39 (18.7%) patients. The dispersion of the corrected QT showed an adequate discrimination capacity in the prediction of any serious ventricular arrhythmic episode (c = 0.768, p = 0.0001). In the multivariate analysis, QT dispersion was an independent predictor of ventricular arrhythmias (OR = 7.075, 95% CI = 1.6-32.9, p = 0.009). Conclusions: The probability of presenting ventricular arrhythmias during acute myocardial infarction is greater when the dispersion of the QT interval is increased, so it is suggested that it should be a variable to be evaluated in the prognostic stratification of acute myocardial infarction.

Cuantificación de la dispersión espacial de la repolarización ventricular cardíaca a través del electrocardiograma de superficie / Quantification of Cardiac Ventricular Repolarization and its Spatial Dispersion through the Surface Electrocardiogram

La dispersión de la repolarización ventricular (DRV) está determinada esencialmente por la heterogeneidad de los potenciales de acción en diferentes regiones del miocardio. Con frecuencia el corazón responde a ciertos estados fisiopatológicos con la producción de un incremento de la DRV, fenómeno éste que puede devenir en una arritmia ventricular maligna y/o en la muerte súbita. Hace 25 años, con el objetivo de identificar a pacientes de riesgo cardíaco, se comenzó a cuantificar la DRV con diversos índices obtenidos por procesamiento computacional del electrocardiograma. Estos índices se basan en la detección de cambios en la duración o en la forma en la onda T en presencia de cardiopatías. En este trabajo se presenta una revisión de los índices de dispersión espacial y su potencialidad como herramienta de apoyo al diagnóstico de riesgo cardíaco.

The ventricular repolarization dispersion (VRD) is determined basically by the heterogeneity of the action potentials in different myocardial regions. Usually the heart responds to certain physiopathological states by producing a VRD increase, which may lead to a malignant ventricular arrhythmia and/or sudden death. For 25 years, the VRD has been quantified with several indexes obtained by computerprocessing the electrocardiogram, in order to identify cardiac- risk patients. These indexes are based on the detection of T wave changes in duration or form, in the presence of cardiopathies. A revision of the spatial dispersion indexes and their potential as supporting tool for the diagnosis of cardiac risk is presented in this work.

QT-interval and its dispersion in type 2 diabetic and non-diabetic patients with post-myocardial infarction and effects of different hypoglycemic drugs on QT-interval dispersion / 中国综合临床

Objective To compare the QTc and QTcd between type 2 diabetic and non-diabetic patients with post-myocardial infarction (post-MI) ,and to compare the QTcd in type 2 diabetic patients with post-MI treated with insulin,sulfonylurea,mefformin,or diet alone. Methods We measured the QTc and QTcd through simultaneous 12-lead Electrocardiogram in 138 post-MI patients,including 70 type 2 diabetic (of which,23 were assigned to re-ceive insulin,20 glipizide,16 mefformin,11 diet control) and 68 non-diabetic patients. Result Compared with post-MI patients without diabetes,those with type 2 diabetes had significantly higher QTc [(377.2±24.3) ms vs (342.9±27.5)ms,t=7.79,P<0.01] and QTcd [(48.8±19.7)ms vs (40.3±26.6)ms,t=2.14,P<0.05]. There were no significant difference between the mefformin group and the diet control group (P>0.05). The QTc and QTcd in the insulin group were significantly higher than those in the other three group s(P<0.05),and the QTc and QTcd in the glipizide group were higher than those in the mefformin group or diet control group(P<0.05,and P<0.01,respectively). Conclusion Type 2 diabetes is associated with an additional increase in the QTcd in post-MI patients,suggesting higher mortality risk in post-MI patients with type 2 diabetes. Insulin and glipizide may in-crease the QTc and QTcd in post-MI patients with diabetes. These effects were more significant in the insulin therapy group.

Effects of Different Hypoglycemic Drugs on QT Interval Dispersion in Patients with Type 2 Diabetes Mellitus / 中国药房

OBJECTIVE:To investigate the effects of different kinds of hypoglycemic drugs on the QT interval dispersion in patients with type 2 diabetes mellitus. METHODS: The differences of QT interval dispersion (QTd) and corrected QT interval dispersion (QTcd) in 318 patients with type 2 diabetes (of which, 129 were assigned to receive insulin, 110 glibenclamide and 79 metformin) and 33 healthy volunteers (normal control) were compared. RESULTS: The QTd and QTcd were all significantly higher in glibenclamide group than in the other three groups(P0.05). CONCLUSION: The results suggest that glibenclamide and insulin may increase the QTd and QTcd in patients with type 2 diabetes.