Unexplained Syncope in Patients With Congenital Long QT Syndrome　- Role of Implantable Loop Recorders in Diagnostic Evaluation.

Authors

Yuichiro Miyazaki, Takeshi Aiba, Koichi Kato, Hideo Fukunaga, Hiroshi Morita, Takahisa Noma, Tatsunori Takahashi, Akira Mizukami, Toshihiro Nakamura, Satoshi Oka, Akinori Wakamiya, Nobuhiko Ueda, Kenzaburo Nakajima, Tsukasa Kamakura, Mitsuru Wada, Kohei Ishibashi, Yuko Inoue, Koji Miyamoto, Satoshi Nagase, Kengo Kusano

Published in

Circulation journal : official journal of the Japanese Circulation Society. Sep 08, 2026. Epub Sep 08, 2026.

Abstract

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.
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.
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.

PMID:
42716773
Bibliographic data and abstract were imported from PubMed on 10 Sep 2026.

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