Acquired long QT syndrome in chronic kidney disease patients

Patients with chronic kidney disease (CKD) have a high risk of fatal arrhythmias. The extended severe corrected QT (QTc) interval is a hallmark of ventricular arrhythmias and sudden cardiac death. The objective of this study was to evaluate the prevalence of acquired long QT syndrome (aLQTS) in hospitalized patients with CKD and search for potential risk factors to improve clinical risk stratification in patients with CKD. Information about patients with CKD was retrospectively collected in our hospital between January 2013 and June 2017. The prevalence of aLQTS in different stages of CKD was evaluated. The common risk factors for QTc prolongation in patients with CKD were compiled, and multivariable logistic regression analysis was used to evaluate how each factor was related to aLQTS in CKD. A total of 804 patients with CKD (299 females, 37.2%) participated in our study. The prevalence of aLQTS among all 804 patients was 56.97%, and the prevalence of QTc prolongation (>500 ms) was 10.07%. Among the elderly, impaired kidney function, hemodialysis, low serum potassium and low left ventricular ejection fraction (LVEF) were associated with QTc prolongation in patients with CKD. The prevalence of aLQTS is much higher and increases with the decline of kidney function in hospitalized patients with CKD, which is related to older age, impaired kidney function, hemodialysis, serum potassium and low LVEF.

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Abstract 5316: hERG 1b as a Potential Target for Inherited and Acquired Long QT Syndrome

Circulation ◽

10.1161/circ.118.suppl_18.s_525-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Gail A Robertson ◽

Harinath Sale ◽

David Tester ◽

Thomas J O’Hara ◽

Pallavi Phartiyal ◽

...

Keyword(s):

Action Potential ◽

Long Qt Syndrome ◽

Time Course ◽

Drug Sensitivity ◽

Long Qt ◽

Hek 293 ◽

Hek 293 Cells ◽

Acquired Long Qt Syndrome ◽

293 Cells ◽

Qt Syndrome

Cardiac I Kr is a critical repolarizing current in the heart and a target for inherited and acquired long QT syndrome. Biochemical studies show that native I Kr channels are heteromers composed of both hERG 1a and 1b subunits, yet our current understanding of I Kr functional properties derives primarily from studies of homo-oligomers of the original hERG 1a isolate. The hERG 1a and 1b subunits are identical except at the amino (NH2) terminus, which in hERG 1b is much shorter and has a unique primary sequence. We compared the biophysical properties of currents produced by hERG 1a and 1a/1b channels expressed in HEK-293 cells at near-physiological temperatures. We found that heteromeric hERG 1a/1b currents are much larger than hERG 1a currents and conduct 80% more charge during an action potential. This surprising difference corresponds to a two-fold increase in the apparent rates of activation and recovery from inactivation, which reduces rectification and facilitates current rebound during repolarization. Kinetic modeling shows these gating differences account quantitatively for the differences in current amplitude between the two channel types. Depending on the action potential model used, loss of 1b predicts an increase in action potential duration of 27 ms (7%) or 41 ms (17%), respectively. Drug sensitivity was also different. Compared to homomeric 1a channels, heteromeric 1a/1b channels were inhibited by E-4031 with a slower time course and a corresponding four-fold positive shift in the IC 50 . Differences in current kinetics and drug sensitivity were modeled by “NH2 mode” gating with conformational states bound by the amino terminus in hERG 1a homomers but not 1a/1b heteromers. The importance of hERG 1b in vivo is supported by the identification of a 1b-specific A8V missense mutation in 1/269 unrelated genotype-negative LQTS patients and absent in 400 control alleles. Mutant 1bA8V expressed alone or with hERG 1a in HEK-293 cells nearly eliminated 1b protein. Thus, mutations specifically disrupting hERG 1b function are expected to reduce cardiac I Kr , prolong QT interval and enhance drug sensitivity, thus representing a potential mechanism underlying inherited or acquired LQTS.

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Pro- and antiarrhythmic effects of fast cardiac pacing in a canine model of acquired long QT syndrome

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/s00210-004-0874-0 ◽

2004 ◽

Vol 369 (4) ◽

pp. 447-454 ◽

Cited By ~ 3

Author(s):

Alexander Bauer ◽

J. Kevin Donahue ◽

Frederik Voss ◽

Ruediger Becker ◽

Patricia Kraft ◽

...

Keyword(s):

Long Qt Syndrome ◽

Cardiac Pacing ◽

Canine Model ◽

Long Qt ◽

Acquired Long Qt Syndrome ◽

Qt Syndrome ◽

Antiarrhythmic Effects

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Prolonged QTc: "Mind the Gap"

Bangladesh Critical Care Journal ◽

10.3329/bccj.v2i1.19970 ◽

2014 ◽

Vol 2 (1) ◽

pp. 44-45

Author(s):

Ahmad Mursel Anam ◽

Raihan Rabbani ◽

Farzana Shumy ◽

M Mufizul Islam Polash ◽

M Motiul Islam ◽

...

Keyword(s):

Cardiac Arrest ◽

Long Qt Syndrome ◽

Qt Interval ◽

Torsades De Pointes ◽

Junior Doctors ◽

Long Qt ◽

Acquired Long Qt Syndrome ◽

Prolonged Qt Interval ◽

Prolonged Qt ◽

Qt Syndrome

We report a case of drug induced torsades de pointes, following acquired long QT syndrome. The patient got admitted for shock with acute abdomen. The initial prolonged QT-interval was missed, and a torsadogenic drug was introduced post-operatively. Patient developed torsades de pointes followed by cardiac arrest. She was managed well and discharged without complications. The clinical manifestations of long QT syndromes, syncope or cardiac arrest, result from torsades de pointes. As syncope or cardiac arrest have more common differential diagnoses, even the symptomatic long QT syndrome are commonly missed or misdiagnosed. In acquired long QT syndrome with no prior suggestive feature, it is not impossible to miss the prolonged QT-interval on the ECG tracing. We share our experience so that the clinicians, especially the junior doctors, will be more alert on checking the QT-interval even in asymptomatic patients. DOI: http://dx.doi.org/10.3329/bccj.v2i1.19970 Bangladesh Crit Care J March 2014; 2 (1): 44-45

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