Prevalence of early-onset atrial fibrillation in congenital long QT syndrome

Heart Rhythm. 2008 May;5(5):704-9. doi: 10.1016/j.hrthm.2008.02.007. Epub 2008 Feb 8.


Background: The prevalence of atrial fibrillation (AF) in the young (age <50 years) is 0.1%, or 1:1,000 persons. Mutations in KCNQ1-, KCNH2-, and KCNA5-encoded potassium channels and SCN5A-encoded sodium channels have been reported in familial AF. A mechanism of atrial torsade has been suggested to occur in patients with congenital long QT syndrome (LQTS).

Objective: The purpose of this study was to determine the prevalence of AF in patients with congenital LQTS.

Methods: History of documented AF was sought from two independent cohorts. One cohort consisted of 252 consecutive patients (146 females and 106 males, average age at diagnosis 23 +/- 16 years, QTc 465 +/- 51 ms) with genetically proven LQTS seen at Mayo's LQTS Clinic. The second cohort consisted of 205 consecutive patients (133 females and 72 males, average age at testing 23 +/- 16 years, QTc 479 +/- 51 ms) with a positive FAMILION genetic test (PGxHealth) for LQTS.

Results: Early-onset AF was documented in 8 (1.7%) of 457 patients, including 6 (2.4%) of 252 patients seen at Mayo and 2 (1%) of 205 patients with a positive FAMILION test. Five (2.4%) of 211 patients with LQT1-susceptibility mutations had documented AF, compared to 0 of 174 patients with LQT2, 1 of 59 patients with LQT3, 1 of 1 patient with Andersen-Tawil syndrome, and 1 of 34 patients with multiple mutations. The average age at diagnosis of AF of the six patients evaluated at Mayo was 24.3 years (range 4-46 years). Early-onset AF (age <50 years) was significantly more common in patients with LQTS compared to population-based prevalence statistics (P <.001, relative risk 17.5).

Conclusion: Compared to the background prevalence of 0.1%, early-onset AF was observed in almost 2% of patients with genetically proven LQTS and should be viewed as an uncommon but possible LQT-related dysrhythmia. Clinical complaints of palpitations warrant thorough assessment in patients with LQTS.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Atrial Fibrillation / epidemiology*
  • Atrial Fibrillation / etiology*
  • Atrial Fibrillation / genetics
  • Child
  • Female
  • Genetic Predisposition to Disease
  • Humans
  • Long QT Syndrome / complications*
  • Long QT Syndrome / epidemiology*
  • Male
  • Potassium Channels, Voltage-Gated / genetics
  • Prevalence
  • Sodium Channels / genetics


  • Potassium Channels, Voltage-Gated
  • Sodium Channels