Which factor may lead to a patient experiencing strokes even after LAAO?

The reason that new thrombus formation outside the device is the correct answer lies in the understanding of the mechanism of strokes related to the left atrial appendage (LAA) and the limitations of LAAO procedures.

LAAO is primarily designed to prevent thrombus formation within the left atrial appendage, which is a common source of emboli leading to strokes in patients with atrial fibrillation. However, once the device is in place, if the patient has other underlying conditions or risk factors that promote thrombus formation in different areas of the cardiovascular system, they can still experience strokes. Potential locations for new thrombus formation include the heart chambers, particularly the left ventricle, or even in the systemic circulation, depending on other health issues the patient may have.

By addressing the opportunities for thrombus formation outside of the LAA, it becomes clear that while LAAO reduces the risk significantly, it does not eliminate the risk of strokes entirely, especially if other factors that promote clot formation are present. Thus, it is essential for patients to continue management of their overall cardiovascular health post-procedure to mitigate other stroke risks.