Unexplained Syncope in Patients With Congenital Long QT Syndrome ― Role of Implantable Loop Recorders in Diagnostic Evaluation ―
Abstract
BACKGROUND: Syncope is common in patients with congenital long QT syndrome (LQTS). However, not all episodes of syncope or loss of consciousness are caused by torsades de pointes (TdP); some are attributable to bradycardia or non-cardiac causes. This study investigated the clinical utility of implantable loop recorders (ILRs) in patients with LQTS presenting with unexplained syncope. METHODS AND RESULTS: We retrospectively studied 18 patients with LQTS (7 with LQTS type (LQT) 1, 3 with LQT2, 1 with LQT3, and 7 genotype-negative LQTS) who underwent ILR implantation for recurrent syncope. Multiple causes of syncope were suspected in each patient; there were 14 cases of arrhythmia, 4 of epilepsy, 8 of neurally mediated syncope (NMS), and 9 of unknown cause. During a mean (±SD) follow-up of 37±22 months after ILR implantation, 8 (44%) patients experienced recurrent syncope. Four episodes were caused by TdP and the remaining 4 episodes were attributed to epilepsy or NMS (cardioinhibitory type). No significant difference was observed in baseline clinical characteristics between patients with and without TdP following ILR implantation, but female sex (P=0.051) and a higher Schwartz score (P=0.08) tended to be associated with TdP. CONCLUSIONS: Syncope in patients with LQTS is not always attributable to TdP, and non-arrhythmic causes should be considered. Although ILRs may aid in diagnostic evaluation, careful risk stratification remains essential in patients with suspected arrhythmic syncope.
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BibTeX
@article{miyazaki2026unexplained,
title = {{Unexplained Syncope in Patients With Congenital Long QT Syndrome ― Role of Implantable Loop Recorders in Diagnostic Evaluation ―}},
author = {Yuichiro Miyazaki and Takeshi Aiba and Koichi Kato and Hideo Fukunaga and Hiroshi Morita and Takahisa Noma and Tatsunori Takahashi and Akira Mizukami and Toshihiro Nakamura and Satoshi Oka and Akinori Wakamiya and Nobuhiko Ueda and Kenzaburo Nakajima and Tsukasa Kamakura and Mitsuru Wada and Kohei Ishibashi and Yuko Inoue and Koji Miyamoto and Satoshi Nagase and Kengo Kusano},
journal = {Circulation Journal},
year = {2026},
month = sep,
doi = {10.1253/circj.cj-26-0111},
url = {https://www.jstage.jst.go.jp/article/circj/advpub/0/advpub_CJ-26-0111/_article},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Unexplained Syncope in Patients With Congenital Long QT Syndrome ― Role of Implantable Loop Recorders in Diagnostic Evaluation ―
AU - Yuichiro Miyazaki
AU - Takeshi Aiba
AU - Koichi Kato
AU - Hideo Fukunaga
AU - Hiroshi Morita
AU - Takahisa Noma
AU - Tatsunori Takahashi
AU - Akira Mizukami
AU - Toshihiro Nakamura
AU - Satoshi Oka
AU - Akinori Wakamiya
AU - Nobuhiko Ueda
AU - Kenzaburo Nakajima
AU - Tsukasa Kamakura
AU - Mitsuru Wada
AU - Kohei Ishibashi
AU - Yuko Inoue
AU - Koji Miyamoto
AU - Satoshi Nagase
AU - Kengo Kusano
PY - 2026
DA - 2026/09/08
JO - Circulation Journal
DO - 10.1253/circj.cj-26-0111
UR - https://www.jstage.jst.go.jp/article/circj/advpub/0/advpub_CJ-26-0111/_article
AB - BACKGROUND: Syncope is common in patients with congenital long QT syndrome (LQTS). However, not all episodes of syncope or loss of consciousness are caused by torsades de pointes (TdP); some are attributable to bradycardia or non-cardiac causes. This study investigated the clinical utility of implantable loop recorders (ILRs) in patients with LQTS presenting with unexplained syncope. METHODS AND RESULTS: We retrospectively studied 18 patients with LQTS (7 with LQTS type (LQT) 1, 3 with LQT2, 1 with LQT3, and 7 genotype-negative LQTS) who underwent ILR implantation for recurrent syncope. Multiple causes of syncope were suspected in each patient; there were 14 cases of arrhythmia, 4 of epilepsy, 8 of neurally mediated syncope (NMS), and 9 of unknown cause. During a mean (±SD) follow-up of 37±22 months after ILR implantation, 8 (44%) patients experienced recurrent syncope. Four episodes were caused by TdP and the remaining 4 episodes were attributed to epilepsy or NMS (cardioinhibitory type). No significant difference was observed in baseline clinical characteristics between patients with and without TdP following ILR implantation, but female sex (P=0.051) and a higher Schwartz score (P=0.08) tended to be associated with TdP. CONCLUSIONS: Syncope in patients with LQTS is not always attributable to TdP, and non-arrhythmic causes should be considered. Although ILRs may aid in diagnostic evaluation, careful risk stratification remains essential in patients with suspected arrhythmic syncope.
SN - 1347-4820
SN - 1346-9843
ER -