Recurrent stroke on imaging and presumed paradoxical embolism

Neurology®, 04/16/2012

The negative findings do not lend support to using the presence of clinical indicators of paradoxical embolism as an indication for percutaneous patent foramen ovale (PFO) closure. Factors that support a paradoxical embolism mechanism may be different from those that predict paradoxical embolism recurrence.

Methods

  • Data from the prospective Tufts PFO Registry collected at the time of the index CS were analyzed.
  • The authors defined the following radiologic markers of stroke recurrence:
    • Strokes of different radiologic ages
    • Silent strokes (detected on MRI but without symptoms preceding the index event).
  • They 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.

Author Commentary

This article allowed us to use a surrogate marker for recurrent stroke that we called "precurrence" - although we didn't put the word into the paper. This is the indisputable presence of a prior stroke on imaging done at the time of the index event. The benefit of this approach is that it allows for the outcome to be much more prevalent (~25% in this cohort) than recurrent clinical stroke and permits analysis without prolonged follow-up. It also introduces the idea of a "provoked" paradoxical embolus. The implication in the literature has frequently been that if you are confident in the diagnosis of PFO (known DVT, Valsalva at onset) then the treatment decision is made (endovascular PFO closure). We attempted to disentangle the confidence of the diagnosis from the risk of recurrence. One could argue that the unprovoked paradoxical emboli, for which diagnostic confidence may be lower, are at higher risk of recurrence because they did not "require" the added risk of DVT and Valsalva and yet they still permitted an embolus to occur. Only well designed randomized clinical trials will help us to determine the treatment effect in different groups of patients.

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