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Arrhythmias & electrophysiologyCohort study

Fetal and Long-Term Maternal Outcomes of New-Onset Arrhythmia During Pregnancy

JACC AdvPublished

  • Epic Cosmos database study
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Authors' conclusion

New-onset AF/AFL and SVT during pregnancy were associated with increased long-term maternal MACE risk, extending well beyond the peripartum period. A first diagnosis of AF/AFL or SVT during pregnancy may identify women at elevated long-term cardiovascular risk warranting structured follow-up.

Study context

Population
Pregnant women with new-onset vs pre-existing AF/AFL or supraventricular tachycardia (SVT) and arrhythmia-free controlsAF/AFL new-onset 2,978 · SVT new-onset 12,860 · AF/AFL pre-existing 2,996 · SVT pre-existing 45,288 · AF/AFL arrhythmia-free 7,676,692 · SVT arrhythmia-free 6,553,510
Participants
2,978 / 2,996 / 7,676,692 / 12,860 / 45,288 / 6,553,510
Exposure
women with new-onset arrhythmia during pregnancy to women with pre-existing arrhythmia and arrhythmia-free women
  • New-onset AF/AFLn = 2,978
  • Pre-existing AF/AFLn = 2,996
  • Arrhythmia-free (AF/AFL cohort)n = 7,676,692reference
  • New-onset SVTn = 12,860reference
  • Pre-existing SVTn = 45,288
  • Arrhythmia-free (SVT cohort)n = 6,553,510reference

Main finding

As reported in the abstract

Long-term maternal major adverse cardiovascular events (MACE), AF/AFL
New-onset AF/AFL
HR 3.18; P < 0.001
Pre-existing AF/AFL
HR 3.02; P < 0.001

Observational data: associations, not effects.

Further findings

OutcomeHRP value
Long-term maternal MACE, SVT — New-onset SVT vs Arrhythmia-free (SVT cohort)1.96P < 0.001
Long-term maternal MACE, SVT — Pre-existing SVT vs Arrhythmia-free (SVT cohort)3.83P < 0.001
Long-term maternal MACE, SVT — Pre-existing SVT vs New-onset SVT · higher risk with pre-existing SVT1.95P < 0.001

Fetal outcomes

Both new-onset and pre-existing AF/AFL were associated with worse fetal outcomes, including preterm birth and stillbirth
new-onset SVT had higher preterm birth risk than pre-existing SVT

Original publication

Fetal and Long-Term Maternal Outcomes of New-Onset Arrhythmia During Pregnancy. JACC Adv. Published 20 August 2026. doi:10.1016/j.jacadv.2026.103135
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Summarised from the published abstract; every number is checked against it