TY - JOUR
T1 - Fragmented QRS is associated with torsades de pointes in patients with acquired long QT syndrome
AU - Haraoka, Kayo
AU - Morita, Hiroshi
AU - Saito, Yukihiro
AU - Toh, Norihisa
AU - Miyoshi, Toru
AU - Nishii, Nobuhiro
AU - Nagase, Satoshi
AU - Nakamura, Kazufumi
AU - Kohno, Kunihisa
AU - Kusano, Kengo F.
AU - Kawaguchi, Kenji
AU - Ohe, Tohru
AU - Ito, Hiroshi
PY - 2010/12
Y1 - 2010/12
N2 - Background Acquired long QT syndrome (LQTS) is a disease due to a secondary repolarization abnormality induced by various predisposing factors. In contrast to congenital LQTS, risk factors that produce acquired LQTS include organic heart diseases that often exhibit depolarization abnormality. Although various repolarization parameters have been evaluated in acquired LQTS, the existence of depolarization abnormality in association with torsades de pointes (TdP) has not been reported. Objective The purpose of this study was to evaluate both repolarization (QT components) and depolarization parameters (fragmented QRS [fQRS]) in acquired LQTS patients with markedly prolonged QT interval. Methods Seventy patients with acquired severe QT prolongation (QTc <550 ms) were studied. Thirty-two patients had syncope or TdP (syncope group). Thirty-eight patients did not have any symptoms (asymptomatic group). The existence of fQRS and QT components (QT, QTc, Tpe [interval between peak and end of T wave] intervals, and U-wave voltage) was analyzed. Results The syncope group had more frequent fQRS (81%) than did the asymptomatic group (21%, P <.01) and the incidence of fQRS was not different before and after removal of predisposing factors. The incidence of organic heart disease was not different between the two groups. No differences in QTc interval were noted between the syncope and asymptomatic groups, although the syncope group had longer QT and Tpe intervals and higher U wave than the asymptomatic group (P <.01). Conclusion Acquired predisposing factors promoted repolarization abnormality (especially prolongation of QT and Tpe intervals), and the existence of fQRS had an important role in the development of TdP in patients with acquired LQTS.
AB - Background Acquired long QT syndrome (LQTS) is a disease due to a secondary repolarization abnormality induced by various predisposing factors. In contrast to congenital LQTS, risk factors that produce acquired LQTS include organic heart diseases that often exhibit depolarization abnormality. Although various repolarization parameters have been evaluated in acquired LQTS, the existence of depolarization abnormality in association with torsades de pointes (TdP) has not been reported. Objective The purpose of this study was to evaluate both repolarization (QT components) and depolarization parameters (fragmented QRS [fQRS]) in acquired LQTS patients with markedly prolonged QT interval. Methods Seventy patients with acquired severe QT prolongation (QTc <550 ms) were studied. Thirty-two patients had syncope or TdP (syncope group). Thirty-eight patients did not have any symptoms (asymptomatic group). The existence of fQRS and QT components (QT, QTc, Tpe [interval between peak and end of T wave] intervals, and U-wave voltage) was analyzed. Results The syncope group had more frequent fQRS (81%) than did the asymptomatic group (21%, P <.01) and the incidence of fQRS was not different before and after removal of predisposing factors. The incidence of organic heart disease was not different between the two groups. No differences in QTc interval were noted between the syncope and asymptomatic groups, although the syncope group had longer QT and Tpe intervals and higher U wave than the asymptomatic group (P <.01). Conclusion Acquired predisposing factors promoted repolarization abnormality (especially prolongation of QT and Tpe intervals), and the existence of fQRS had an important role in the development of TdP in patients with acquired LQTS.
KW - Acquired long QT syndrome
KW - Fragmented QRS
KW - Predisposing factor
KW - Repolarization reserve
KW - Torsades de pointes
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U2 - 10.1016/j.hrthm.2010.09.008
DO - 10.1016/j.hrthm.2010.09.008
M3 - Article
C2 - 20837161
AN - SCOPUS:78650127407
VL - 7
SP - 1808
EP - 1814
JO - Heart Rhythm
JF - Heart Rhythm
SN - 1547-5271
IS - 12
ER -