Arrhythmias & electrophysiology

A population-based study of trends in cardiac arrest and sudden death owing to long QT syndrome

Heart RhythmPublished population-based study

Authors' conclusion

Decreasing rates of LQTS detection in recent years suggest that most cases have been discovered in New Zealand. Decreasing cardiac arrest and sudden death owing to LQTS is likely related to the success of the overall program.

Study context

Population
Registry participants who underwent genetic testing for long QT syndrome (LQTS) presenting between 2000 and 2023, New Zealanddiagnosed as having LQTS, 378 probands
Participants
915 participants
Outcome
Presentation of probands
Methodological detailsnational LQTS registry
  • National LQTS registry

Main finding

As reported in the abstract

Mean corrected QT interval
512 ± 52 ms
Sudden cardiac death
26 of 378; 7%
Resuscitated cardiac arrest (RSCA)
82; 21%
Syncope or seizure
122; 32%
Incidental/other
148; 40%

Observational data: associations, not effects.

Further findings

Causative genetic variants in probands

Causative genetic variants found
165 of 378 probands (44%)
KCNQ1, of the 165 with variants
98 KCNQ1 (59%)
KCNH2, of the 165 with variants
41 KCNH2 (25%)
SCN5A, of the 165 with variants
7 SCN5A (4%)
Other genes, of the 165 with variants
19 other genes (12%)

Therapy

On therapy
593 of 915 participants (65%)
Beta blocker
565; 62%
Implantable cardioverter-defibrillator
134; 16%
Left cardiac sympathetic denervation
69; 8%

Events during follow-up · median 12 years

Likely arrhythmic deaths
3 likely arrhythmic deaths (0.3%)
Appropriate implantable cardioverter-defibrillator shocks
23 appropriate implantable cardioverter-defibrillator shocks (3%)

Detections of LQTS/population

2000
0.5 of 100,000
2009
1.6 of 100,000
2023
0.4 of 100,000

Presentation with RSCA · from 2007

Decreased per year
10%/y

Presentation with death · from 2014

Decreased per year
22%/y
P
P = 0.026
No deaths from 2019 to 2023

Original publication

A population-based study of trends in cardiac arrest and sudden death owing to long QT syndrome. Heart Rhythm. Published 26 February 2026. doi:10.1016/j.hrthm.2026.02.033

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