title: Absence of an association between anti-Ro antibodies and prolonged QTc interval in systemic sclerosis: a multicenter study of 689 patients.
abstract: OBJECTIVE
  To examine the association between anti-Ro antibodies, namely anti-Ro60/SS-A and anti-Ro52/TRIM21, together and separately, and a prolonged QT interval corrected for heart rate (QTc) in systemic sclerosis (SSc) patients.
  
  
  METHODS
  A total of 689 SSc patients enrolled in a multicenter cohort study underwent a 12-lead resting EKG at baseline. The QTc interval was measured, and a QTc ≥ 440ms was considered prolonged. Detailed clinical data and sera of these patients were collected and positivity for anti-Ro60/SS-A and anti-Ro52/TRIM21 antibodies was determined using an addressable laser bead immunoassay (ALBIA).
  
  
  RESULTS
  QTc prolongation was common in this SSc cohort (25%). In a univariate analysis, Ro antibodies, together or separately, were not associated with prolongation of the QTc interval [mean difference in QTc in anti-Ro antibody positive versus negative subjects was -2.2ms (p = 0.5748), in anti-Ro60/SS-A antibody positive versus negative subjects was 1.3ms (p = 0.8616), and in anti-Ro52/TRIM21 antibody positive versus negative subjects was -3.3ms (p = 0.4106)]. In a multivariate logistic regression analysis adjusting for possible confounders, there was no association between prolonged QTc and anti-Ro antibodies [odds ratio (OR) = 0.74, 95% confidence interval (CI): 0.45, 1.22], anti-Ro60/SS-A antibodies (OR = 1.57, 95% CI: 0.72, 3.41), and anti-Ro52/TRIM21 antibodies (OR = 0.76, 95% CI: 0.46, 1.26). However, in both univariate and multivariate analyses, QTc prolongation was associated with longer disease duration, greater disease severity, and the presence of anti-RNA polymerase III antibodies.
  
  
  CONCLUSIONS
  QTc prolongation is common in SSc, although anti-Ro antibodies do not seem to be associated with it as is the case in systemic lupus erythematosus. The reasons for this difference as well as the cause of abnormalities in cardiac repolarization in SSc will require additional studies.
authors.affiliation: Department of Medicine, McGill University, Montréal, Quebec, Canada.
authors.forename: Charles
authors.initials: C
authors.lastname: Massie
authors.affiliation: Department of Medicine, McGill University, Montréal, Quebec, Canada; Division of Rheumatology, Jewish General Hospital, Room A-725, 3755 Côte Sainte-Catherine Rd, Montréal, Quebec, Canada H3T 1E2; Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada. Electronic address: marie.hudson@mcgill.ca.
authors.forename: Marie
authors.initials: M
authors.lastname: Hudson
authors.affiliation: Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada.
authors.forename: Solène
authors.initials: S
authors.lastname: Tatibouet
authors.affiliation: Lady Davis Institute, Jewish General Hospital, Montréal, Quebec, Canada; Department of Mathematics, McGill University, Montréal, Quebec, Canada.
authors.forename: Russell
authors.initials: R
authors.lastname: Steele
authors.affiliation: Department of Medicine, McGill University, Montréal, Quebec, Canada; Division of Cardiology, McGill University Health Center, Montreal, Quebec, Canada.
authors.forename: Thao
authors.initials: T
authors.lastname: Huynh
authors.affiliation: Faculty of Medicine, Department of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Marvin J
authors.initials: MJ
authors.lastname: Fritzler
authors.affiliation: Department of Medicine, McGill University, Montréal, Quebec, Canada; Division of Rheumatology, Jewish General Hospital, Room A-725, 3755 Côte Sainte-Catherine Rd, Montréal, Quebec, Canada H3T 1E2.
authors.forename: Murray
authors.initials: M
authors.lastname: Baron
authors.affiliation: Department of Medicine, McGill University, Montréal, Quebec, Canada; Division of Rheumatology, McGill University Health Center, Montreal, Quebec, Canada.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Pineau
mesh_terms: D000368:Aged; D000888:Antibodies, Anti-Idiotypic / Q000097:blood*; D015331:Cohort Studies; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D053208:Kaplan-Meier Estimate; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012595:Scleroderma, Systemic / Q000097:blood / Q000276:immunology* / Q000503:physiopathology*; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D000888:Antibodies, Anti-Idiotypic
keywords: Anti-Ro antibodies; Anti-Ro52/TRIM21; Anti-Ro60/SS-A; Autoantibodies; Congenital heart block; Myocardial fibrosis; QTc prolongation; Systemic sclerosis