Recurrent stroke on imaging and presumed paradoxical embolism

OBJECTIVE: To identify whether factors supporting a diagnosis of paradoxical embolism (i.e., venous thrombosis or Valsalva maneuver) are associated with radiologic markers of recurrent strokes in patients with patent foramen ovale (PFO) and cryptogenic stroke (CS). Such clinical indicators of paradoxical embolism are commonly viewed as risk factors for CS recurrence, but precise risk estimates are lacking. METHODS: Data from the prospective Tufts PFO Registry collected at the time of the index CS were analyzed. We defined the following radiologic markers of stroke recurrence: 1) strokes of different radiologic ages and 2) silent strokes (detected on MRI but without symptoms preceding the index event). We examined the association between the radiologic endpoints and the clinical indicators of paradoxical embolism with multivariate logistic regression models, adjusting for age and gender. RESULTS: Data were available for 224 subjects. Strokes of different radiologic ages were not associated with the thrombosis-predisposing conditions (1.2 [95% confidence interval 0.5-2.7]), the Valsalva maneuver (1.3 [0.6-3.1]), or the presence of either of these factors. No statistically significant association was found in subgroups stratified by anatomic location of the index stroke or for the outcome of silent strokes. CONCLUSIONS: Our negative findings do not lend support to using the presence of clinical indicators of paradoxical embolism as an indication for percutaneous PFO closure. Factors that support a paradoxical embolism mechanism may be different from those that predict paradoxical embolism recurrence. Further investigations with clinical follow-up and larger sample sizes are needed to reach more precise estimates for the associations examined.