title: Transvenous pacing leads and systemic thromboemboli in patients with intracardiac shunts: a multicenter study.
abstract: BACKGROUND
  The risk of systemic thromboemboli associated with transvenous leads in the presence of an intracardiac shunt is currently unknown.
  
  
  RESULTS
  To define this risk, we conducted a multicenter, retrospective cohort study of 202 patients with intracardiac shunts: Sixty-four had transvenous leads (group 1), 56 had epicardial leads (group 2), and 82 had right-to-left shunts but no pacemaker or implantable cardioverter defibrillator leads (group 3). Patient-years were accrued until the occurrence of systemic thromboemboli or study termination. Censoring occurred in the event of complete shunt closure, death, or loss to follow-up. Mean ages for groups 1, 2, and 3 were 33.9+/-18.0, 22.2+/-12.6, and 22.9+/-15.0 years, respectively. Respective oxygen saturations were 91.2+/-9.1%, 88.1+/-8.1%, and 79.7+/-6.7%. During respective median follow-ups of 7.3, 9.3, and 17.0 years, 24 patients had at least 1 systemic thromboembolus: 10 (15.6%), 5 (8.9%), and 9 (11.0%) in groups 1, 2, and 3, respectively. Univariate risk factors were older age (hazard ratio [HR], 1.05; P=0.0001), ongoing phlebotomy (HR, 3.1; P=0.0415), and an transvenous lead (HR, 2.4; P=0.0421). In multivariate, stepwise regression analyses, transvenous leads remained an independent predictor of systemic thromboemboli (HR, 2.6; P=0.0265). In patients with transvenous leads, independent risk factors were older age (HR, 1.05; P=0.0080), atrial fibrillation or flutter (HR, 6.7; P=0.0214), and ongoing phlebotomy (HR, 14.4; P=0.0349). Having had aspirin or warfarin prescribed was not protective. Epicardial leads were, however, associated with higher atrial (P=0.0407) and ventricular (P=0.0270) thresholds and shorter generator longevity (HR, 1.9; P=0.0176).
  
  
  CONCLUSIONS
  Transvenous leads incur a >2-fold increased risk of systemic thromboemboli in patients with intracardiac shunts.
authors.affiliation: Adult Congenital Heart and Electrophysiology Services, Montreal Heart Institute, Montreal, Canada. paul.khairy@umontreal.ca
authors.forename: Paul
authors.initials: P
authors.lastname: Khairy
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Landzberg
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gatzoulis
authors.forename: Lise-Andrée
authors.initials: LA
authors.lastname: Mercier
authors.forename: Susan M
authors.initials: SM
authors.lastname: Fernandes
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Côté
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lavoie
authors.forename: Anne
authors.initials: A
authors.lastname: Fournier
authors.forename: Peter G
authors.initials: PG
authors.lastname: Guerra
authors.forename: Alexandra
authors.initials: A
authors.lastname: Frogoudaki
authors.forename: Edward P
authors.initials: EP
authors.lastname: Walsh
authors.forename: Annie
authors.initials: A
authors.lastname: Dore
mesh_terms: D001166:Arteriovenous Shunt, Surgical / Q000379:methods*; D002304:Cardiac Pacing, Artificial; D015331:Cohort Studies; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000145:classification / Q000453:epidemiology / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007431:Intraoperative Complications / Q000453:epidemiology; D010138:Pacemaker, Artificial; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013923:Thromboembolism / Q000453:epidemiology / Q000601:surgery*