Do LQTS Gene Single Nucleotide Polymorphisms Alter QTc Intervals at Rest and during Exercise Stress Testing?. Issue 3 (20th January 2013)

• Record Type: Journal Article
• Authors: Aziz, Peter F.; Wieand, Tammy S.; Ganley, Jamie; Henderson, Jacqueline; McBride, Michael; Shah, Maully J.
• Is Part Of: Annals of noninvasive electrocardiology. Volume 18:Issue 3(2013:May)
• Page Start: 288
• Page End: 293
• Publication Date: 2013-01-20
• Subjects: Electrocardiography -- Periodicals; Arrhythmia -- Periodicals; 616.1207547
• DOI: 10.1111/anec.12037
• Languages: English
• ISSNs: 1082-720X

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="anec12037-sec-0010" sec-type="section"> <title>Background</title> <p>The impact of harboring, genetic variants or single nucleotide polymorphisms (LQT‐PM) on the repolarization response during exercise and recovery is unknown.</p> </sec> <sec id="anec12037-sec-0020" sec-type="section"> <title>Objective</title> <p>To assess the QTc interval adaptation during exercise stress testing (EST) in children with LQT polymorphisms compared to a group of age and gender matched normal controls.</p> </sec> <sec id="anec12037-sec-0030" sec-type="section"> <title>Methods</title> <p>One hundred forty‐eight patients were age and gender matched into two groups: LQT‐PM and control. Each patient underwent a uniform exercise protocol employing a cycle ergometer followed by a 9 minute recovery phase with continuous 12‐lead electrocardiogram (ECG) monitoring. Intervals (RR, QT and QTc) at rest (supine), peak exercise and in recovery (1, 3, 5, 7, and 9 minutes) were measured.</p> </sec> <sec id="anec12037-sec-0040" sec-type="section"> <title>Results</title> <p>Forty‐three patients were positive for LQT‐PM and the control group consisted of 105 patients. A total of 83 SNPs were identified: <italic>SCN5A</italic> n = 31 (37%), <italic>KCNE1</italic> n = 29 (35%), <italic>KCNH2</italic> n = 20 (24%), <italic>KCNQ1</italic> n = 2 (2%) and <italic>KCNE2</italic> n = 1 (1%). The QTc interval measurements of the LQT‐PM were longer at rest, peak exercise and all phases of recovery when compared to the control group. Neither group demonstrated abnormal QTc interval adaptation in response to exercise. Patients with homozygous SNPs had longer resting QTc intervals when compared to patients with only heterozygous SNPs (435 ± 23 ms vs. 415 ± 20 ms, respectively, <italic>P</italic> value <0.006).</p> </sec> <sec id="anec12037-sec-0050" sec-type="section"> <title>Conclusions</title> <p>Individuals with LQT‐PM may have longer QTc intervals at rest as well as at peak exercise and all phases of the recovery period compared to normal controls. Additionally, subjects with homozygous SNPs had longer resting QTc intervals when compared to those with only heterozygous SNPs.</p> </sec> </abstract>