Test Characteristics of Electrocardiography for Detection of Left Ventricular Hypertrophy in Asymptomatic Emergency Department Patients With Hypertension

Objectives The objective was to evaluate the diagnostic test characteristics of three validated electrocardiographic (ECG) criteria for the diagnosis of left ventricular hypertrophy (LVH) in undifferentiated, asymptomatic emergency department (ED) patients with hypertension (HTN). Methods This was a prospective cohort study of ED patients with asymptomatic HTN at a single tertiary care facility. Patients 35 years of age or older with systolic blood pressure (sBP) ≥ 140 mm Hg or diastolic blood pressure (dBP) ≥ 90 mm Hg on two separate readings (at least 1 hour apart) were eligible for inclusion. At enrollment, ECGs were obtained for all patients. Presence of LVH on ECG was defined using Cornell voltage, Cornell product, and Minnesota Code 3.1/3.2 criteria. Echocardiography was then performed, with LVH defined by the presence of one or more of the following validated criteria: interventricular septal or posterior wall thickness ≥ 1.3 cm, LV mass ≥ 225 g (male) or ≥ 163 g (female), or LV mass indexed to height raised to the power of 2.7 ≥ 48 g/m2.7 (male) or ≥ 45 g/m2.7 (female). Descriptive statistics and diagnostic characteristics (i.e., sensitivity and specificity) with corresponding 95% confidence intervals (CIs) for each of the three ECG criteria were derived for both the composite and the individual echocardiographic determinants of LVH. Logistic regression was also used to model LVH before and after subsequent inclusion of clinically relevant variables. Results A total of 161 patients (93.8% African American; mean [±SD] age = 49.8 [±8.3] years) were enrolled, and LVH was present in 89 patients (55.2%, 95% CI = 47.6% to 62.8%). On ECG analysis, mean Cornell voltage (21.5 mV vs. 28.7 mV; difference = –7.2 mV, 95% CI = –3.8 to –10.7 mV) and Cornell product (1868.4 msec × mV vs. 2616.4 msec × mV; difference = –748.0 msec × mV, 95% CI = –401.2 to –1094.8 msec × mV) were significantly lower among those without LVH on echocardiography. Subjects without LVH on echocardiography were less likely to meet Cornell voltage (30.5% vs. 48.3%; difference = –17.8%, 95% CI = –2.5% to –31.7%) or Cornell product (26.4% vs. 49.4%; difference = –23.0%, 95% CI = –8.0% to –36.5%) criteria for LVH. The diagnosis of LVH by Minnesota Code was less common (18.1% vs. 25.8%; difference = –7.7%, 95% CI = –20.1% to 5.3%) with no difference by group. Sensitivity and specificity were as follows: for the Cornell voltage, sensitivity 25.4% (95% CI = 15.3% to 37.9%), specificity 50.0% (95% CI = 67.6% to 93.2%); for the Cornell product, sensitivity 25.4% (95% CI = 15.3% to 37.9%), specificity 75.0% (95% CI = 19.4% to 99.4%); and for the Minnesota code, sensitivity 26.9% (95% CI = 16.6% to 39.7%), specificity 75.0% (95% CI = 19.4% to 99.4%). On logistic regression, the c-statistics for Cornell voltage and Cornell product were equivalent (0.67), with only marginal improvement after the addition of body mass index (BMI; 0.69 and 0.70, respectively), B-type natriuretic peptide (BNP; 0.68 and 0.69, respectively), or both (0.71 and 0.72, respectively) to the models. Conclusions In this cohort of predominately African American ED patients with asymptomatic HTN, sensitivity and specificity of standard ECG criteria were relatively poor for the diagnosis of LVH on echocardiography. Thus, ECG is of limited use for LVH risk stratification in asymptomatic ED patients with elevated blood pressure, with additional clinical information only modestly strengthening its predictive value. Resumen Objetivos Evaluar las caracteristicas de la prueba diagnostica de tres criterios electrocardiograficos (ECG) validados para el diagnostico de la hipertrofia ventricular izquierda (HVI) en pacientes con hipertension (HTA) asintomatica del servicio de urgencias (SU). Metodologia Estudio de cohorte prospectivo de pacientes con HTA asintomatica del SU en un centro de nivel terciario. Se incluyo a los pacientes de 35 anos o mas con una presion arterial sistolica (PAS) ≥ 140 mm Hg o una presion arterial diastolica (PAD) ≥ 90 mm Hg en dos lecturas separadas (al menos 1 hora de diferencia). En el momento del reclutamiento se realizo un ECG a todos ellos. La presencia de HVI en el ECG se definio segun los criterios de voltaje de Cornell, el producto de Cornell, y el Minnesota Code 3.1/3.2. Se realizo una ecocardiografia, y se definio la HVI por la presencia de uno o mas de los siguientes criterios validados: espesor del septo interventricular o de la pared posterior ≥ 1,3 cm; masa del VI ≥ 225g (varones) o ≥163g (mujeres); masa del VI indexada por el peso elevado a la potencia de 2,7 ≥ 48 g/m2.7 en varones) o ≥ 45 g/m2.7 en mujeres. Los estadisticos descriptivos y las caracteristicas diagnosticas (sensibilidad y especificidad) con sus correspondientes intervalos de confianza (IC) al 95% para cada uno de los tres criterios ECG se derivaron tanto para los determinantes ecocardiograficos individuales y compuestos de HVI. Se uso un modelo de regresion logistica para el modelo HVI antes y despues tras la inclusion de las variables clinicamente relevantes. Resultados Se incluyeron 161 pacientes (93,8% de raza negra, edad media 49,8 anos [DE ± 8,3 anos]) y 89 pacientes (55,2%, IC 95% = 47,6% al 62,8%) presentaron HVI. En el analisis del ECG, la media de voltaje de Cornell (21,5 vs 28,7 mV; diferencia –7,2 mV [IC 95% = –3,8 a –10.7mv]) y del producto de Cornell (1868,4 vs 2616,4 ms × mV; diferencia –748,0 ms × mV [IC del 95% = –401,2 a –1094,8 ms × mV]) fueron significativamente menores entre aquellos sin HVI en la ecocardiografia. Los sujetos sin HVI en la ecocardiografia tenian menor probabilidad de cumplir los criterios de voltaje de Cornell (30,5% vs 48,3%; diferencia –17,8% [IC 95% = –2,5% al –31,7%]) o del producto de Cornell (26,4% vs 49,4%; diferencia –23,0% [IC 95% = –8,0% al –36,5]). El diagnostico de HVI mediante el Minnesota Code fue menos frecuente (18,1% vs 25,8%; diferencia –7,7% [IC 95% = –20,1% al 5,3%]), sin diferencias entre ambos grupos. La sensibilidad y la especificidad fueron los siguientes: para el voltaje de Cornell, la sensibilidad fue de un 25,4% (IC 95% = 15,3% al 37,9%), la especificidad de un 50,0% (IC 95% = 67,6% al 93,2%); para el producto de Cornell, la sensibilidad fue de un 25,4% (IC 95% = 15,3% al 37,9%), la especificidad de un 75,0% (IC 95% = 19,4% al 99,4%); y para Minnesota code, la sensibilidad fue de un 26,9% (IC 95% = 16,6% al 39,7%) y la especificidad de un 75,0% (IC 95% = 19,4% al 99,4). En la regresion logistica, los c-estadisticos para el voltaje de Cornell y el producto de Cornell fueron equivalentes (0,67), con solo una mejoria minima despues de la adicion a los modelos del indice de masa corporal (0,69 y 0,70, respectivamente), del peptido natriuretico tipo B (0,68 y 0,69, respectivamente) o de ambos (0,71 y 0,72, respectivamente). Conclusiones En esta cohorte de pacientes del SU de predominio afroamericano con HTA asintomatica, la sensibilidad y la especificidad de los criterios ECG estandar fueron relativamente pobres para el diagnostico ecografico de HVI. Por tanto, el ECG es de uso limitado para la estratificacion del riesgo de pacientes asintomaticos del SU con presion arterial elevada, y la informacion clinica adicional fortalece solo modestamente su valor predictivo.