scholarly journals Age-Gender Influence on the Rate-Corrected QT Interval and the QT-Heart Rate Relation in Families With Genotypically Characterized Long QT Syndrome

1997 ◽  
Vol 29 (1) ◽  
pp. 93-99 ◽  
Author(s):  
Michael H Lehmann ◽  
Katherine W Timothy ◽  
Debra Frankovich ◽  
Barbara S Fromm ◽  
Mark Keating ◽  
...  
Keyword(s):  
Heart Rate ◽  
Long Qt Syndrome ◽  
Qt Interval ◽  
Long Qt ◽  
Corrected Qt Interval ◽  
Gender Influence ◽  
Qt Syndrome ◽  
Rate Relation

Reproducibility of corrected QT interval in pediatric genotyped long QT syndrome

2016 ◽  
Vol 58 (11) ◽  
pp. 1246-1248
Author(s):  
Yoshiharu Ogawa ◽  
Toshikatsu Tanaka ◽  
Sachiko Kido
Keyword(s):  
Long Qt Syndrome ◽  
Qt Interval ◽  
Long Qt ◽  
Corrected Qt Interval ◽  
Qt Syndrome

scholarly journals P1793Impact of QTc formulae in the prevalence of long corrected QT interval and impact on risk of Long QT Syndrome

EP Europace ◽  
2017 ◽  
Vol 19 (suppl_3) ◽  
pp. iii396-iii396
Author(s):  
R. Providencia ◽  
N. Srinivasan ◽  
N. Karim ◽  
S. Honarbakhsh ◽  
MJ. Ferreira ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Qt Interval ◽  
Long Qt ◽  
Corrected Qt Interval ◽  
Qt Syndrome

scholarly journals Corrected QT Interval–Polygenic Risk Score and Its Contribution to Type 1, Type 2, and Type 3 Long-QT Syndrome in Probands and Genotype-Positive Family Members

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Kari L. Turkowski ◽  
Steven M. Dotzler ◽  
David J. Tester ◽  
John R. Giudicessi ◽  
J. Martijn Bos ◽  
...  
Keyword(s):  
General Population ◽  
Risk Score ◽  
Long Qt Syndrome ◽  
Genetic Variants ◽  
Qt Interval ◽  
Polygenic Risk Score ◽  
Long Qt ◽  
Polygenic Risk ◽  
Corrected Qt Interval ◽  
Qt Syndrome

Background: Long-QT syndrome (LQTS) is characterized by a prolonged heart rate–corrected QT interval (QTc). Genome-wide association studies identified common genetic variants that collectively explain ≈8% to 10% of QTc variation in the general population. Methods: Overall, 423 patients with LQT1, LQT2, or LQT3 were genotyped for 61 QTc-associated genetic variants used in a prototype QTc–polygenic risk score (QTc-PRS). A weighted QTc-PRS (range, 0–154.8 ms) was calculated for each patient, and the FHS (Framingham Heart Study) population-based reference cohort (n=853). Results: The average QTc-PRS in LQTS was 88.0±7.2 and explained only ≈2.0% of the QTc variability. The QTc-PRS in LQTS probands (n=137; 89.3±6.8) was significantly greater than both FHS controls (87.2±7.4, difference-in-means±SE: 2.1±0.7, P <0.002) and LQTS genotype-positive family members (87.5±7.4, difference-in-mean, 1.8±.7, P <0.009). There was no difference in QTc-PRS between symptomatic (n=156, 88.6±7.3) and asymptomatic patients (n=267; 87.7±7.2, difference-in-mean, 0.9±0.7, P=0.15). LQTS patients with a QTc≥480 ms (n=120) had a significantly higher QTc-PRS (89.3±6.7) than patients with a QTc<480 ms (n=303, 87.6±7.4, difference-in-mean, 1.7±0.8, P <0.05). There was no difference in QTc-PRS or QTc between genotypes. Conclusions: The QTc-PRS explained <2% of the QTc variability in our LQT1, LQT2, and LQT3 cohort, contributing 5× less to their QTc value than in the general population. This prototype QTc-PRS does not distinguish/predict the clinical outcomes of individuals with LQTS.

Individualized corrected QT interval is superior to QT interval corrected using the Bazett formula in predicting mutation carriage in families with long QT syndrome

Heart Rhythm ◽  
2017 ◽  
Vol 14 (3) ◽  
pp. 376-382 ◽  
Author(s):  
Tomas Robyns ◽  
Rik Willems ◽  
Bert Vandenberk ◽  
Joris Ector ◽  
Christophe Garweg ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
Qt Interval ◽  
Long Qt ◽  
Corrected Qt Interval ◽  
Qt Syndrome

scholarly journals Response of the QT interval to mental and physical stress in types LQT1 and LQT2 of the long QT syndrome

Heart ◽  
2001 ◽  
Vol 86 (1) ◽  
pp. 39-44
Author(s):  
K J Paavonen ◽  
H Swan ◽  
K Piippo ◽  
L Hokkanen ◽  
P Laitinen ◽  
...  
Keyword(s):  
Heart Rate ◽  
Serum Potassium ◽  
Long Qt Syndrome ◽  
Qt Interval ◽  
Mental Stress ◽  
Physical Stress ◽  
Exercise Stress ◽  
Long Qt ◽  
Qt Intervals ◽  
Qt Syndrome

OBJECTIVETo study and compare the effects of mental and physical stress on long QT syndrome (LQTS) patients.DESIGNCase–control study.MAIN OUTCOME MEASURESQT intervals were measured from lead V3. Serum potassium and plasma catecholamine concentrations were also monitored.PATIENTS16 patients with type 1 LQTS (LQT1), 14 with type 2 LQTS (LQT2), both groups asymptomatic, and 14 healthy control subjects.INTERVENTIONSThree types of mental stress tests and a submaximal exercise stress test.RESULTSHeart rate responses to mental stress and exercise were similar in all groups. During mental stress, the mean QT interval shortened to a similar extent in controls (–29 ms), LQT1 patients (–34 ms), and LQT2 patients (–30 ms). During exercise, the corresponding QT adaptation to exercise stress was more pronounced (p < 0.01) in healthy controls (–47 ms) than in LQT1 (–38 ms) or LQT2 patients (–38 ms). During exercise changes in serum potassium concentrations were correlated to changes in QT intervals in controls, but not in LQTS patients. LQT1 and LQT2 patients did not differ in serum potassium, catecholamine or heart rate responses to mental or physical stress.CONCLUSIONSQT adaptation to mental and exercise stress in healthy people and in patients with LQTS is different. In healthy people QT adaptation is more sensitive to physical than to mental stress while no such diverging pattern was seen in asymptomatic LQTS patients.

“QT-Stunning:” the Abnormal Response of the QT Interval to Brisk Standing Persists Even as the Heart Rate Returns to Baseline in Patients with Long QT Syndrome

Heart Rhythm ◽  
2010 ◽  
Vol 7 (11) ◽  
pp. 1718-1719
Author(s):  
Arnon Adler ◽  
Sami Viskin ◽  
Christian van der Werf ◽  
Pieter Postema ◽  
Raphael Rosso ◽  
...  
Keyword(s):  
Heart Rate ◽  
Long Qt Syndrome ◽  
Qt Interval ◽  
Long Qt ◽  
Abnormal Response ◽  
Qt Syndrome

scholarly journals Long QT syndrome in children: the value of the rate corrected QT interval in children who present with fainting

2001 ◽  
Vol 8 (4) ◽  
pp. 178-182 ◽  
Author(s):  
W.C. Allan ◽  
K. Timothy ◽  
G.M. Vincent ◽  
G.E. Palomaki ◽  
L.M. Neveux ◽  
...  
Keyword(s):  
Long Qt Syndrome ◽  
False Positive ◽  
Qt Interval ◽  
False Positives ◽  
Long Qt ◽  
Corrected Qt Interval ◽  
History Of ◽  
Qt Syndrome

OBJECTIVE:A strategy was evaluated for identifying a proportion of children with long QT syndrome (LQTS) using the rate corrected QT interval (QTc) to systematically evaluate children who faint. METHODS:QTc measurements and rates of fainting for the present analysis are available from families with KVLQT1, HERG, or SCN5A genotypes. QTc distributions in affected and unaffected children were documented and detection and false positive rates were modelled. RESULTS:The mean QTc (SD) in 117 affected children was 0.484 seconds (0.031), and 0.420 seconds (0.021) among 133 unaffected children. At a cut off of 0.49 seconds, QTc measurement will identify 42.5% of affected and 0.1% of unaffected persons with a history of fainting who are alive at the time of testing. Assumptions include a prevalence of 1:5000 for LQTS, 2% mortality with the first arrhythmia, and a rate of fainting of 50% in affected children and 7% in unaffected children. Given these variables, a QTc cut off of 0.49 seconds detects 42 of 200 affected, along with 70 unaffected children out of a population of 1 million. If QTc ≥0.49 seconds is found in either parent of children with a QTc of 0.44 through 0.48 seconds, another 21 affected and 25 unaffected children will be identified. CONCLUSION:Systematically performing QTc measurements as part of the evaluation of children who faint might optimally identify about one third of patients with LQTS with few false positives and thereby offer an opportunity to prevent some sudden deaths.

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