F10 and atrial fibrillation: Therefore, it seems conceivable that the survival benefit found in this subcohort might even be underestimated, because patients with AC treatment in general, and FXa-i therapy in particular, tend to represent a cohort with negative prognostic properties as compared to patients not receiving AC, due to a higher rate of TEE and other comorbidities (i.e., atrial fibrillation, previous cardiovascular events, or VTE).