TY - JOUR
T1 - Long QT syndrome complicating atrioventricular block
T2 - Arrhythmogenic effects of cardiac memory
AU - Rosso, Raphael
AU - Adler, Arnon
AU - Strasberg, Boris
AU - Guevara-Valdivia, Milton E.
AU - Somani, Riyaz
AU - Baranchuk, Adrian
AU - Halkin, Amir
AU - Márquez, Manlio F.
AU - Scheinman, Melvin
AU - Steinvil, Arie
AU - Belhassen, Bernard
AU - Kazatsker, Mark
AU - Katz, Amos
AU - Viskin, Sami
N1 - Publisher Copyright:
© 2014 American Heart Association, Inc.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - Background: The magnitude of QT prolongation in response to bradycardia, rather than the bradycardia per se, determines the risk for torsade de pointes during atrioventricular block (AVB). However, we do not know why some patients develop more QT prolongation than others, despite similar bradycardia. We hypothesized that in patients who develop significant QRS vector changes during AVB, the effects of cardiac memory lead to excessive QT prolongation. Methods and Results: We studied 91 patients who presented with AVB and who also had an ECG predating the bradyarrhythmia for comparison. We correlated changes in QRS morphology and axis taking place during AVB with the bradycardia-induced QT prolongation. Patients with and without QRS morphology changes at the time of AVB were of similar age and sex. Moreover, despite similar R-R interval during AVB, cases with a QRS morphology change had significantly longer QT (648±84 versus 561±84; P<0.001) than those without. Patients who developed a change in QRS morphology at the time of AVB had a 7-fold higher risk of developing long QT. This risk nearly doubled when the change in QRS morphology was accompanied by a change in QRS axis. Conclusions: Cardiac memory resulting from a change in QRS morphology during AVB is independently associated with QT prolongation and may be arrhythmogenic during AVB.
AB - Background: The magnitude of QT prolongation in response to bradycardia, rather than the bradycardia per se, determines the risk for torsade de pointes during atrioventricular block (AVB). However, we do not know why some patients develop more QT prolongation than others, despite similar bradycardia. We hypothesized that in patients who develop significant QRS vector changes during AVB, the effects of cardiac memory lead to excessive QT prolongation. Methods and Results: We studied 91 patients who presented with AVB and who also had an ECG predating the bradyarrhythmia for comparison. We correlated changes in QRS morphology and axis taking place during AVB with the bradycardia-induced QT prolongation. Patients with and without QRS morphology changes at the time of AVB were of similar age and sex. Moreover, despite similar R-R interval during AVB, cases with a QRS morphology change had significantly longer QT (648±84 versus 561±84; P<0.001) than those without. Patients who developed a change in QRS morphology at the time of AVB had a 7-fold higher risk of developing long QT. This risk nearly doubled when the change in QRS morphology was accompanied by a change in QRS axis. Conclusions: Cardiac memory resulting from a change in QRS morphology during AVB is independently associated with QT prolongation and may be arrhythmogenic during AVB.
KW - Atrioventricular block
KW - Long QT syndrome
KW - Torsade de pointes
UR - http://www.scopus.com/inward/record.url?scp=84925547729&partnerID=8YFLogxK
U2 - 10.1161/CIRCEP.114.002085
DO - 10.1161/CIRCEP.114.002085
M3 - Article
AN - SCOPUS:84925547729
SN - 1941-3149
VL - 7
SP - 1129
EP - 1135
JO - Circulation: Arrhythmia and Electrophysiology
JF - Circulation: Arrhythmia and Electrophysiology
IS - 6
ER -