OBJECTIVES: The purpose of this study was to characterize the effect of epinephrine on T-wave morphology in patients with congenital long QT syndrome (LQTS). BACKGROUND: QT prolongation is a paradoxical, LQT1-specific response to low-dose epinephrine infusion. At rest, notched T waves are more common in LQT2. METHODS: Thirty subjects with LQT1, 28 with LQT2, and 32 controls were studied using epinephrine provocation. Twelve-lead ECG was recorded continuously, and QT, QTc, and heart rate were obtained during each stage. Blinded to phenotype and genotype, T-wave morphology was classified as normal, biphasic, G1 (notch at or below the apex), or G2 (distinct protuberance above the apex). RESULTS: At baseline, 97% LQT1, 71% LQT2, and 94% control had normal T-wave profiles. During epinephrine infusion, G1- and G2-T waves were more common in LQT2 than in LQT1 (75% vs 26%, P = .009). However, epinephrine-induced G1-T waves were present in 34% of control. Epinephrine-precipitated biphasic T waves were observed similarly in all groups: LQT1 (6/30), LQT2 (3/28), and control (4/32). During low-dose epinephrine infusion (< or =0.05 microg/kg/min), G1-T waves occurred more frequently in LQT2 (LQT1: 25% vs 3%; control 9%, P = .02). Low-dose epinephrine-induced G2-T waves were detected exclusively in LQT2 (18%). Low-dose epinephrine elicited G1/G2-T waves in 8 of 15 LQT2 patients with a nondiagnostic baseline QTc. CONCLUSIONS: Biphasic and G1-T waves are nonspecific responses to high-dose epinephrine. Changes in T-wave morphology during low-dose epinephrine (<0.05 microg/kg/min) may yield diagnostic information. G2-notched T waves elicited during low-dose epinephrine may unmask some patients with concealed LQT2.
OBJECTIVES: The purpose of this study was to characterize the effect of epinephrine on T-wave morphology in patients with congenital long QT syndrome (LQTS). BACKGROUND:QT prolongation is a paradoxical, LQT1-specific response to low-dose epinephrine infusion. At rest, notched T waves are more common in LQT2. METHODS: Thirty subjects with LQT1, 28 with LQT2, and 32 controls were studied using epinephrine provocation. Twelve-lead ECG was recorded continuously, and QT, QTc, and heart rate were obtained during each stage. Blinded to phenotype and genotype, T-wave morphology was classified as normal, biphasic, G1 (notch at or below the apex), or G2 (distinct protuberance above the apex). RESULTS: At baseline, 97% LQT1, 71% LQT2, and 94% control had normal T-wave profiles. During epinephrine infusion, G1- and G2-T waves were more common in LQT2 than in LQT1 (75% vs 26%, P = .009). However, epinephrine-induced G1-T waves were present in 34% of control. Epinephrine-precipitated biphasic T waves were observed similarly in all groups: LQT1 (6/30), LQT2 (3/28), and control (4/32). During low-dose epinephrine infusion (< or =0.05 microg/kg/min), G1-T waves occurred more frequently in LQT2 (LQT1: 25% vs 3%; control 9%, P = .02). Low-dose epinephrine-induced G2-T waves were detected exclusively in LQT2 (18%). Low-dose epinephrine elicited G1/G2-T waves in 8 of 15 LQT2patients with a nondiagnostic baseline QTc. CONCLUSIONS: Biphasic and G1-T waves are nonspecific responses to high-dose epinephrine. Changes in T-wave morphology during low-dose epinephrine (<0.05 microg/kg/min) may yield diagnostic information. G2-notched T waves elicited during low-dose epinephrine may unmask some patients with concealed LQT2.
Authors: Arnon Adler; Christian van der Werf; Pieter G Postema; Raphael Rosso; Zahir A Bhuiyan; Jonathan M Kalman; Jitendra K Vohra; Milton E Guevara-Valdivia; Manlio F Marquez; Amir Halkin; Jesaia Benhorin; Charles Antzelevitch; Arthur A M Wilde; Sami Viskin Journal: Heart Rhythm Date: 2012-01-31 Impact factor: 6.343
Authors: Sami Viskin; Raphael Rosso; Ori Rogowski; Bernard Belhassen; Aviva Levitas; Abraham Wagshal; Amos Katz; Dana Fourey; David Zeltser; Antonio Oliva; Guido D Pollevick; Charles Antzelevitch; Uri Rozovski Journal: Eur Heart J Date: 2005-08-16 Impact factor: 29.983