Arrhythmias & electrophysiologyCohort study
Association Between Syncope Trigger Type and Risk of Subsequent Life-Threatening Events in Patients With Long QT Syndrome
- Retrospective cohort study
- multicentre
- 5 international long QT syndrome (LQTS) registries
Authors' conclusion
In this study, trigger-specific syncope in LQTS patients was associated with differential risk of subsequent LTE and response to β-blocker therapy.
Study context
- Population
- Patients with genetically confirmed LQT1, LQT2 or LQT3 from a single LQTS-causative variant, enrolled July 1979 to July 2021
- Participants
- 2,938 patients
- Exposure
- Adrenergic- vs nonadrenergic-triggered syncope
- Outcome
- First occurrence of a life-threatening event (LTE)
Main finding
As reported in the abstract
First LTE, by genotype
Hazard ratio (95% CI)P value
ADLQT1
7.61(4.18–14.20)
P < 0.001non-ADLQT1
1.50(0.21–4.77)
P = 0.97ADLQT2
3.07(1.66–5.67)
P ≤ 0.001non-ADLQT2
3.45(1.96–6.06)
P ≤ 0.001- LQT3: LTE preceded by syncope
- 7 (12%)
Observational data: associations, not effects.
Further findings
First syncope and syncope preceding LTE, by genotype
- LQT1: first syncope
- 365 (27%)
- LQT1: syncope with adrenergic (AD) triggers
- 243 [67%]
- LQT1: syncope preceded life-threatening events (LTEs)
- 43 (68%)
- LQT2: first syncope
- 283 (26%)
- LQT2: AD / non-AD triggers
- 106 (37%) / 177 (63%)
- LQT2: syncope preceded LTEs
- 55 (56%)
- LQT3 (n = 501): LTE preceded by syncope
- 7 (12%)
β-blockers after syncope (LQT1 and LQT2)
- β-blockers associated with significant reduction in subsequent LTE risk
- Breakthrough events significantly higher with selective vs nonselective agents
Original publication
Association Between Syncope Trigger Type and Risk of Subsequent Life-Threatening Events in Patients With Long QT Syndrome. JAMA Cardiol. Published 1 August 2023. doi:10.1001/jamacardio.2023.1951
Summarised from the published abstract; every number is checked against it