Document Detail


Heart rate-dependent variability of cardiac events in type 2 congenital long-QT syndrome.
MedLine Citation:
PMID:  20880952     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
AIMS: We aimed to examine the validity of heart rate (HR) at rest before β-blocker therapy as a risk factor influencing cardiac events (ventricular fibrillation, torsades de pointes, or syncope) in long QT type 2 (LQT2) patients.
METHODS AND RESULTS: In 110 genetically confirmed LQT2 patients (45 probands), we examined the significance of variables [HR at rest, corrected QT (QTc), female gender, age of the first cardiac event, mutation site] as a risk factor for cardiac events. We also evaluated frequency of cardiac events in four groups classified by the combination of basal HR and QTc with cutoff values of 60 b.p.m. and 500 ms to estimate if these two electrocardiographic parameters in combination could be a good predictor of outcome (mean follow-up period: 50 ± 39 months). Logistic regression analysis revealed three predictors: HR < 60 b.p.m., QTc ≥ 500 ms, and female gender. When the study population was divided into four groups using the cutoff values of 60 b.p.m. for HR and 500 ms for QTc, the cumulative event-free survival by the Kaplan-Meier method was significantly higher in the group with HR ≥ 60 b.p.m. and QTc < 500 ms than in the group with HR < 60 b.p.m. and QTc < 500 ms or that with HR < 60 b.p.m. and QTc ≥ 500 m (P < 0.05). Irrespective of QTc interval, LQT2 patients with basal HR < 60 b.p.m. were at significantly higher risk.
CONCLUSION: The basal HR of < 60 b.p.m. is a notable risk factor for the prediction of life-threatening arrhythmias in LQT2 patients.
Authors:
Iori Nagaoka; Wataru Shimizu; Yuka Mizusawa; Tomoko Sakaguchi; Hideki Itoh; Seiko Ohno; Takeru Makiyama; Ken-ichiro Yamagata; Hisaki Makimoto; Yoshihiro Miyamoto; Shiro Kamakura; Minoru Horie
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-29
Journal Detail:
Title:  Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology     Volume:  12     ISSN:  1532-2092     ISO Abbreviation:  Europace     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100883649     Medline TA:  Europace     Country:  England    
Other Details:
Languages:  eng     Pagination:  1623-9     Citation Subset:  IM    
Affiliation:
Department of Cardiovascular and Respiratory Medicine, Shiga University of Medical Science, Seta, Tsukinowa-cho, Otsu, Shiga 520-2192, Japan.
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