Índice de varianza versus duración del complejo QRS para el diagnóstico de dispersión mecánica del ventrículo izquierdo

Introducción. En el complejo universo de la falla cardíaca, el pronóstico y el tratamiento de la misma sumaron un aspecto de valor durante la última década del siglo pasado, a partir del reconocimiento de la disincronía mecánica durante la sístole y las consiguientes propuestas de resincronización cardíaca. Desde los inicios la predicción de disincronía mecánica se ha fundamentado en la duración del complejo QRS, las imágenes y más recientemente el análisis del índice de varianza del QRS. Objetivo. Tomando como estándar la dispersión mecánica ventricular izquierda medida por ecocardiografía, valorar la concordancia entre duración promedio del QRS del electrocardiograma (ECG) versus el índice de varianza, en cuanto a sensibilidad, especificidad y valor predictivo de dispersión anormal. Métodos. Población de pacientes consecutivos citados para ecocardiografía strain, sin escara ventricular, para medir dispersión mecánica, duración promedio del QRS del ECG e índice de varianza espacial. Resultados. Se evaluaron 54 pacientes y 57 escenarios distintos. Edad promedio: 66,3±14,2 años; duración promedio del QRS fue de 119,7±31,5 mseg. El índice de varianza promedio fue 0,52±0,35. Un índice de varianza >0,4 demostró sensibilidad y especificidad de 82,6% y 64,7% respectivamente, para diagnóstico de dispersión mecánica anormal (e"56 mseg); valor predictivo positivo: 61,3%, negativo: 84,6%. La duración promedio de QRS e"130 mseg logró sensibilidad y especificidad de 52,6% y 71%, con valores predictivos positivo y negativo de 54,5% y 68,6%, respectivamente. La duración promedio del QRS no guarda dependencia con la disincronía mecánica (p=0,1458); la disincronía mecánica (>56 mseg) y la electrocardiografía de varianza, por otra parte, sí guardan dependencia muy significativa (p=0,0012). Los métodos no son comparables para diagnosticar disincronía (kappa=0,376). Conclusión. El ECG de varianza tiene mejor sensibilidad y valor predictivo negativo para el diagnóstico de dispersión mecánica ventricular izquierda valorada por ecocardiografía.

Introduction. The prediction of mechanical dyssynchrony has generally been based on the duration of the QRS complex, although other resources are available, such as the QRS variance index; these methods have not been compared with each other. Objective. Taking as a standard the left ventricular mechanical dispersion measured by speckle-tracking strain echocardiography, to assess the concordance between the average QRS duration of the standard electrocardiogram versus the spatial variance index in terms of sensitivity, specificity and predictive value of abnormal mechanical dispersion. Methods. Population of consecutive patients cited for strain echocardiography and without ventricular scar tissue, to measure mechanical dispersion, average QRS duration of the standard electrocardiogram and the variance index. Results. Fifty-four patients and 57 different scenarios were evaluated; the average age was 66.3±14.2 years, the QRS average duration on standard electrocardiogram was 119.7±31.5 ms. Average ID was 0.52±0.35. A spatial variation index >0.4 showed sensitivity and specificity of 82.6% and 64.7% respectively, for the diagnosis of abnormal mechanical dispersion (e"56 ms); positive predictive value: 61.3%, negative: 84.6%. The average duration of QRS e"130 ms achieved sensitivity and specificity of 52.6% and 71%, and the positive and negative predictive values were 54.5 and 68.6%, respectively. The average QRS duration are not interdependent with mechanical dyssynchrony (p=0.1458); mechanical dyssynchrony (>56 ms) and spatial variance electrocardiography are, nevertheless, clearly interdependent (p=0.0012). The methods are not comparable between them (kappa=0.376). Conclusion. The QRS variation electrocardiogram has better sensitivity and negative predictive value respect to the average QRS duration for the diagnosis of left ventricular mechanical dispersion prevalence, measured by echocardiography.

Introdução. No complexo universo da insuficiência cardíaca, seu prognóstico e tratamento agregaram valor durante a última década do século passado, com base no reconhecimento da dissincronia mecânica durante a sístole e nas propostas subsequentes de ressincronização cardíaca. Desde o início, a previsão da dissincronia mecânica tem sido baseada na duração do complexo QRS, nas imagens e, mais recentemente, na análise do índice de variância QRS. Objetivo. Tomando como padrão a dispersão mecânica do ventrículo esquerdo medida pelo ecocardiograma, avalie a concordância entre a duração média do QRS do eletrocardiograma (ECG) versus o índice de variância, em termos de sensibilidade, especificidade e valor preditivo de dispersão anormal. Métodos População de pacientes consecutivos citados para ecocardiograma de deformação, sem escara ventricular, para medir dispersão mecânica, duração média do QRS do ECG e índice de variância espacial. Resultados. Foram avaliados 54 pacientes e 57 cenários diferentes. Idade média: 66,3±14,2 anos; a duração média do QRS foi de 119,7±31,5 mseg. O índice de variância médio foi de 0,52±0,35. Um índice de variância >0,4 mostrou sensibilidade e especificidade de 82,6% e 64,7%, respectivamente, para diagnóstico de dispersão mecânica anormal (e"56 mseg); valor preditivo positivo: 61,3%, negativo: 84,6%. A duração média do QRS e"130 mseg alcançou sensibilidade e especificidade de 52,6% e 71%, com valores preditivos positivos e negativos de 54,5% e 68,6%, respectivamente. A duração média do QRS não depende de dissincronia mecânica (p=0,1458); dissincronia mecânica (>56 mseg) e eletrocardiografia de variância, por outro lado, têm dependência muito significativa (p=0,0012). Os métodos não são comparáveis para diagnosticar dissincronia (kappa=0,376). Conclusão. A variância do ECG apresenta melhor sensibilidade e valor preditivo negativo para o diagnóstico de dispersão mecânica do ventrículo esquerdo avaliada pelo ecocardiograma.

The change of left ventricular function and mechanical dispersion in patients with hypertrophic cardiomyopathy :a study with exercise stress echocardiography / 中华超声影像学杂志

To investigate the association between the change of left ventricular ( LV ) function and mechanical dispersion ( MD ) and exercise capacity in patients with hypertrophic cardiomyopathy ( HCM ) by exercise stress echocardiography . Methods Sixty‐five HCM patients [ 40 cases of hypertrophic non‐obstructive cardiomyopathy ( HNCM ) , 25 cases of hypertrophic obstructive cardiomyopathy ( HOCM ) ] and 25 control subjects were recruited .LV function ,MD and exercise capacity were evaluated by two‐dimensional speckle‐tracking imaging and echocardiography at rest and during exercise ,and the following parameters of LV function were recorded : LV global longitudinal strain ( LVGLS) ,MD ,early diastolic strain rate ( Sre) ,the ratio of peak early diastolic mitral inflow and annulus velocity ( E/e′) ,LV outflow tract gradient ( LVO TG) ; LV functional reserve was assessed by ΔLVGLS and ΔSRe ; exercise capacity was evaluated by metabolic equivalents ( M ET s ) . T he association between the change of LV function and MD and exercise capacity was investigated . Results ①Compared with normal controls ,LVO TG ,E/e′ and MD increased ,and LVGLS ,Sre , ΔLVGLS , ΔSRe and M ET s decreased in HNCM patients at rest and during exercise ( all P ＜ 0 .05 ) . ② LVO TG , E/e′ and MD were further increased ,LVLGS ,Sre ,ΔSRe and M Ets were further reduced in HOCM patients compared with HNCM patients ( all P ＜ 0 .05 ) . ③LVGLS and MD measured at peak exercise were associated with M ET s ( r ＝－0 .68 , P ＜ 0 .001 ; r ＝ －0 .43 , P ＜ 0 .001 ) . ④ ROC curve analysis showed LVGLS had a better predictive value for exercise intolerance in HCM patients ,followed by E/e′ and MD . Conclusions LV function and mechanic reserve are reduced but MD is increased in HCM patients ,especially in HOCM patients . Exercise capacity is associated with LV function and MD ,w hich can predict the reduced exercise capacity in HCM patients .

The impact of overt hypothyroidism on left ventricular mechanical synchrony : speckle tracking echocardiography study / 中华超声影像学杂志

Objective To explore the impact of hypothyroidism on left ventricular ( LV ) mechanics using two-dimensional speckle tracking imaging ( 2D-STI ) . Methods Forty-two patients with newly diagnosed overt hypothyroidism ( HT ) were prospectively collected as the case group and 47 subjects matching by age ,gender and hypertension history were enrolled as control group . All participants received comprehensive echocardiography examination ,and 2D-STI was used to assess LV global longitudinal strain ( GLS) and mechanical dispersion ( MD ) . The inter-group difference in GLS and MD ,correlations with thyroid hormones and reproducibility were evaluated . Results LV GLS at both sectional ( apical 4- ,3- ,2-chamber views) and global levels were significantly impaired in the HT group than the control group [ ( - 21 .3 ± 3 .2) ％ vs ( - 23 .9 ± 2 .9) ％ ,( - 20 .4 ± 3 .8 ) ％ vs ( - 22 .7 ± 2 .9 ) ％ ,( - 21 .2 ± 3 .9) ％ vs ( - 23 .9 ± 2 .5) ％ ,( - 20 .9 ± 3 .4) ％ vs ( - 23 .5 ± 2 .3) ％ ;all P < 0 .01] . Similarly ,MD at both sectional ( apical 4- ,3- ,2-chamber views) and global levels were significantly prolonged in the HT group than the control group[ 3 .4 ms vs 0 .9 ms ,2 .2 ms vs 0 .7 ms ,2 .3 ms vs 1 .7 ms and 12 .2 ms vs ( 5 .9 ± 2 .6) ms ;all P < 0 .01] . No significant correlation was found between MD and GLS ,left ventricular ejection fraction ( LVEF) ( r = 0 .12 , P = 0 .27 ; r = - 0 .17 , P = 0 .10) . Weak correlations were found between MD and FT3 ,FT4 ,TSH( r = - 0 .34 , P = 0 .01 ; r = - 0 .38 , P = 0 .005 ; r = 0 .31 , P = 0 .02) . Conclusions Primary overt HT is associated with impaired LV deformation and increased systolic dyssynchrony . LV MD is a promising parameter for assessment of myocardial impairment in HT .