Detection rate by time period and predictors of serious arrhythmias in unexplained syncope: a multicenter implantable loop recorder registry study

Background/Aims Although an implantable loop recorder (ILR) is a valuable tool for investigation of unexplained syncope, there are limited data regarding time course to diagnosis and predictors of serious arrhythmias as a cause of unexplained syncope. We sought to investigate diagnosis rate by time...

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Main Authors: Juwon Kim, Il-Young Oh, Myung-Jin Cha, Jinhee Ahn, So-Ryoung Lee, Sung Ho Lee, Jae-Sun Uhm, Pil-Sung Yang, Jaemin Shim, Hyoung-Seob Park, Junbeom Park, Jun Hyung Kim, Ki-Hun Kim, Jumsuk Ko, Hong Euy Lim, Ju Youn Kim
Format: Article
Language:English
Published: The Korean Association of Internal Medicine 2025-07-01
Series:The Korean Journal of Internal Medicine
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Online Access:http://kjim.org/upload/kjim-2024-364.pdf
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Summary:Background/Aims Although an implantable loop recorder (ILR) is a valuable tool for investigation of unexplained syncope, there are limited data regarding time course to diagnosis and predictors of serious arrhythmias as a cause of unexplained syncope. We sought to investigate diagnosis rate by time period after ILR implantation and identify predictors of serious arrhythmias in patients with unexplained syncope. Methods We identified 394 patients who received ILR implantation for unexplained syncope enrolled in the Korean ILR registry. Results Serious arrhythmias were documented in 205 patients (52.0%). One hundred seventy-two patients (43.7%) had sick sinus-node syndrome (SSS), 24 (6.1%) had atrioventricular block, and nine (2.3%) had ventricular arrhythmia. Of these, 48 (23.4%) and 77 (37.6%) were diagnosed within two weeks and one month after ILR implantation, respectively. Median time to diagnosis was 62 days. In multivariable analysis, left atrial volume index (LAVI) ≥ 34 mL/m2 (hazard ratio [HR] 1.582), hypertension (HR 1.788), sinus bradycardia with a heartrate less than 60 beats per minute (HR 1.762), and LAVI ≥ 34 mL/m2 combined with sinus bradycardia (HR 1.911) were independent predictors of SSS. Cumulative detection rate of SSS was significantly higher in patients with LAVI ≥ 34 mL/m2 than those with LAVI < 34 mL/m2 (p < 0.001). Conclusions More than half of patients with unexplained syncope had serious arrhythmias, and more than one-third of these arrhythmias were diagnosed within one month after ILR implantation. LAVI combined with sinus bradycardia may be a useful predictor of SSS as a cause of unexplained syncope.
ISSN:1226-3303
2005-6648