title: Oral contraceptive use and the ECG: evidence of an adverse QT effect on corrected QT interval.
abstract: BACKGROUND
  A prolonged corrected QT (QTc) interval is a marker for an increased risk of sudden cardiac death. We evaluated the relationship between oral contraceptive (OC) use, type of OC, and QTc interval.
  
  
  METHODS
  We identified 410,782 ECGs performed at Northern California Kaiser Permanente on female patients between 15 and 53 years from January, 1995 to June, 2008. QT was corrected for heart rate using log-linear regression. OC generation (first, second and third) was classified by increasing progestin androgenic potency, while the fourth generation was classified as antiandrogenic.
  
  
  RESULTS
  Among 410,782 women, 8.4% were on OC. In multivariate analysis after correction for comorbidities, there was an independent shortening effect of OCs overall (slope = -0.5 ms; SE = 0.12, P < 0.0002). Users of first and second generation progestins had a significantly shorter QTc than nonusers (P < 0.0001), while users of fourth generation had a significantly longer QTc than nonusers (slope = 3.6 ms, SE = 0.35, P < 0.0001).
  
  
  CONCLUSIONS
  Overall, OC use has a shortening effect on the QTc. Shorter QTc is seen with first and second generation OC while fourth generation OC use has a lengthening effect on the QTc. Careful examination of adverse event rates in fourth generation OC users is needed.
authors.affiliation: Women's Heart Center, Cedars-Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
authors.forename: Tara
authors.initials: T
authors.lastname: Sedlak
authors.forename: Chrisandra
authors.initials: C
authors.lastname: Shufelt
authors.forename: Carlos
authors.initials: C
authors.lastname: Iribarren
authors.forename: Liisa L
authors.initials: LL
authors.lastname: Lyon
authors.forename: C Noel
authors.initials: CN
authors.lastname: Bairey Merz
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D002140:California; D003276:Contraceptives, Oral / Q000008:administration & dosage* / Q000009:adverse effects* / Q000145:classification; D003430:Cross-Sectional Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D015999:Multivariate Analysis; D012016:Reference Values; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
chemical_list: D003276:Contraceptives, Oral
keywords: QT; hormones