[QT interval shortening in families with history of sudden death at young age]
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Updated: Aug 25, 2026
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Published on: January 16, 2019
Insights
Shortened QT intervals are common in children with a family history of young sudden death. This finding suggests a need for further investigation into genetic cardiac conditions.
Area of Science:
- Cardiology
- Genetics
- Pediatrics
Context:
- Sudden death in young individuals (<40 years) without obvious cause is a significant concern.
- Family history of early sudden death often indicates underlying genetic predispositions.
- The QT interval on an electrocardiogram (ECG) reflects ventricular repolarization and can be a marker for cardiac channelopathies.
Purpose:
- To determine the frequency of short QT intervals in children from families with a history of young sudden death.
- To investigate the correlation between shortened QT intervals and unexplained early sudden cardiac death in familial contexts.
Summary:
- Eleven children (ages 3-16) from families with unexplained sudden death underwent ECG analysis.
- A significant proportion (81.1%) exhibited shortened QT intervals, defined as less than 88% of the predicted QT value.
- Three children with syncope showed QT intervals at 80% of predicted, alongside a high family burden of sudden death.
Impact:
- Identifies shortened QT interval as a characteristic finding in pediatric cases with a family history of early sudden death.
- Highlights the importance of ECG screening for short QT intervals in at-risk children.
- Suggests that QT interval duration below 88% of predicted warrants exclusion of specific cardiac diseases and syndromes associated with sudden death risk.
Aim:
To assess frequency of short QT interval among members of families with history of young age sudden death.
Material:
Eleven children aged 3-16 years (mean age 11.2+/-4.2 years) from families with cases of sudden death at young age (<40 years) not caused by an obvious disease according to autopsy data. None of the probands had overt heart disease, life threatening arrhythmias, long QT syndrome.
Methods:
Predicted QT value was estimated according to the P. Rautaharju formula [QT(p)=656/(1+HR/100)], and values equal to 80 and 88% of QT(p) (QT(p)80 and QT(p)88) were determined. Corrected QT interval duration (QT(c)) was calculated for all these values with the use of the Bazett formula.
Results:
Values of corrected QT(c)88 370 ms and 350 ms were considered minimal for heart rates above and below 78 bpm, respectively. QT shortening to the level of QT(p)80 at heart rates above 70 bpm corresponded to QT(c) values <330 ms. Nine of 11 children (81.1%) had QT interval equal to or less than QT(p)88. Three probands with attacks of syncope had QT equal to QT(p)80, high concentration of sudden deaths in family (up to 30% of family members), and high prevalence of shortened QT <80% among family members.
Conclusion:
Shortened QT interval is characteristic for children with family history of sudden death at young age. Registration of QT duration equal to or shorter than 88% of predicted value requires exclusion of diseases and syndromes with increased risk of sudden death.
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