**5.4 Implications of acute diagnosis**

Unless the patient presents with a prior history of APS, the diagnosis of APS will likely be in question during the acute and subacute stroke window. This is because APS by laboratory criteria needs to be performed 12-weeks apart with two positive tests to confirm. That said, a patient that presents with a stroke and has one or more laboratory results that are concerning for APS (positive LA, aCL, anti-β2GPI), there is a question if confirming APS would change acute management. Oftentimes, the answer is yes; this even in the setting of likely APS, because thrombosis can be multifactorial and can progress between confirmatory APS testing [67]. As such, management should focus on appropriate treatment for the source of the stroke. For example, if the source is cardioembolic, the timing of initiation of anticoagulation should be considered, weighing the risk of a second embolic event while not on indicated therapy versus the risk of hemorrhagic conversion of the primary infarct.
