Background—
The risk of systemic thromboemboli associated with transvenous leads in the presence of an intracardiac shunt is currently unknown.
Methods and 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.