Stroke or Transient Ischemic Attack in Patients With Transvenous Pacemaker or Defibrillator and Echocardiographically Detected Patent Foramen Ovale
Is the presence of a patent foramen ovale (PFO) in patients with implanted right heart leads associated with risk of stroke or transient ischemic attack (TIA)?
This retrospective single-center study examined 6,075 patients undergoing transvenous implantation of pacemaker or cardioverter-defibrillator leads in the right heart and echocardiography imaging. The risk of stroke or TIA was compared between patients with versus without a PFO on echocardiography. Standard echocardiography included routine assessment of the atrial septum by color Doppler; saline contrast studies were performed only when judged clinically necessary. Patients with possible, but not confirmed PFO were excluded from the study.
Mean follow-up was 4.7 ± 3.1 years. From the overall population, 6% (364/6,075) had a definite PFO. Patients with (vs. without) PFO had increased history of atrial fibrillation (49% vs. 44%, p = 0.03), although there were no other significant differences between groups regarding age, gender, hypertension, or other risk factors. Stroke/TIA was observed in 30 (8.2%) patients with a PFO versus 117 (2.0%) without a PFO (p < 0.001). The presence of a PFO was associated with increased risk of stroke/TIA on univariate analysis (hazard ratio, 3.5; 95% confidence interval, 2.3-5.2; p < 0.001). This remained significant after adjusting for age, gender, history of stroke/TIA, history of atrial fibrillation, and use of warfarin and aspirin at the time of device implantation (hazard ratio, 3.4; 95% confidence interval, 2.2-5.1; p < 0.001). There was no significant difference in all-cause unadjusted or adjusted mortality between groups.
The authors concluded that the presence of PFO on echocardiography is associated with an increased risk of stroke or TIA in patients with implanted cardiac leads.
This study raises important clinical questions, especially given the large number of patients with intracardiac devices and leads, and the common occurrence of PFOs. Even after adjusting for risk factors, patients with a PFO had an over threefold increased risk of stroke or TIA, and this difference persisted despite adjustment for risk factors including baseline aspirin and warfarin use. While intriguing, this study raises several questions. As saline contrast studies were not uniformly performed, and as transesophageal echocardiography was performed only in a small subset of patients, it is likely that many PFOs were missed during this study. It is unclear whether routine performance of saline contrast studies and transesophageal echocardiography would identify an additional cohort of patients with intracardiac leads and a PFO at increased risk of stroke or TIA. Further, while adjustment was made for baseline aspirin and warfarin use, it is not clear whether there were differences between groups at the time of the index event or follow-up. Most importantly, while this study identifies a relationship between PFO and risk of stroke or TIA, it is not clear whether a medical or procedural intervention would change this risk, and future studies are therefore needed.
Keywords: Stroke, Ischemic Attack, Transient, Foramen Ovale, Patent, Pacemaker, Artificial
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