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Revista Española de Cardiología (English Edition) Revista Española de Cardiología (English Edition)
Rev Esp Cardiol. 2017;70:907-14 - Vol. 70 Num.11 DOI: 10.1016/j.rec.2017.01.006

Value of the “Standing Test” in the Diagnosis and Evaluation of Beta-blocker Therapy Response in Long QT Syndrome

Carmen Muñoz-Esparza a,, Esther Zorio b, Diana Domingo Valero b, Pablo Peñafiel-Verdú a, Juan J. Sánchez-Muñoz a, Esperanza García-Molina a, María Sabater a, Marina Navarro a, Irene San-Román a, Inmaculada Pérez a, Juan J. Santos a, Valentín Cabañas-Perianes c, Mariano Valdés a, Domingo Pascual a, Arcadio García-Alberola a, Juan R. Gimeno Blanes a

a Unidad de Cardiopatías Familiares, Hospital Clínico Universitario Virgen de la Arrixaca, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria, Murcia, Spain
b Unidad de Valoración del Riesgo de Muerte Súbita Familiar, Servicio de Cardiología, Hospital Universitario y Politécnico La Fe, Valencia, Spain
c Departamento de Hematología y Análisis Clínico, Hospital Clínico Universitario Virgen de la Arrixaca, Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria, Murcia, Spain

Refers to

Diagnosis of Long QT Syndrome: Time to Stand Up!
Andrea Mazzanti, Silvia G. Priori
Rev Esp Cardiol. 2017;70:898-900
Full text - PDF

Keywords

Long QT syndrome. Standing test. Corrected QT interval. T wave morphology. Beta-blocker therapy.

Abstract

Introduction and objectives

Patients with congenital long QT syndrome (LQTS) have an abnormal QT adaptation to sudden changes in heart rate provoked by standing. The present study sought to evaluate the standing test in a cohort of LQTS patients and to assess if this QT maladaptation phenomenon is ameliorated by beta-blocker therapy.

Methods

Electrographic assessments were performed at baseline and immediately after standing in 36 LQTS patients (6 LQT1 [17%], 20 LQT2 [56%], 3 LQT7 [8%], 7 unidentified-genotype patients [19%]) and 41 controls. The corrected QT interval (QTc) was measured at baseline (QTcsupine) and immediately after standing (QTcstanding); the QTc change from baseline (ΔQTc) was calculated as QTcstanding – QTcsupine. The test was repeated in 26 patients receiving beta-blocker therapy.

Results

Both QTcstanding and ΔQTc were significantly higher in the LQTS group than in controls (QTcstanding, 528 ± 46 ms vs 420 ± 15 ms, P < .0001; ΔQTc, 78 ± 40 ms vs 8 ± 13 ms, P < .0001). No significant differences were noted between LQT1 and LQT2 patients. Typical ST-T wave patterns appeared after standing in LQTS patients. Receiver operating characteristic curves of QTcstanding and ΔQTc showed a significant increase in diagnostic value compared with the QTcsupine (area under the curve for both, 0.99 vs 0.85; P < .001). Beta-blockers attenuated the response to standing in LQTS patients (QTcstanding, 440 ± 32 ms, P < .0001; ΔQTc, 14 ± 16 ms, P < .0001).

Conclusions

Evaluation of the QTc after the simple maneuver of standing shows a high diagnostic performance and could be important for monitoring the effects of beta-blocker therapy in LQTS patients.

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1885-5857/© 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved