Positive antiphospholipid antibodies increase the risk of ischemic stroke in patients with atrial fibrillation.

BACKGROUND

Antiphospholipid antibodies (aPL), including lupus anticoagulant, antibodies against β2 glycoprotein I (anti-β2GPI), and anticardiolipin (aCL) antibodies are associated with ischemic stroke (IS). Their prevalence and clinical relevance in atrial fibrillation (AF) remain unclear.

OBJECTIVES

To assess whether aPL are associated with increased risk of IS in AF patients despite anticoagulation.

METHODS

We conducted a post hoc analysis of aPL using blood samples from 243 consecutive AF patients enrolled in a cohort study. Markers of a prothrombotic state, including endogenous thrombin potential, fibrin clot permeability, and lysis time, were measured at baseline. During a median follow-up of 52 months, IS/transient ischemic attack and major bleeding were recorded.

RESULTS

We observed aPL at a moderate or high titer in 51 (21%) patients, including 17 (7%) with anti-β2GPI, 19 (7.8%) with aCL antibodies, and 37 (15.2%) with lupus anticoagulant. aPL-positive patients were more likely to have prior stroke (P = .01) and be active smokers (P = .03), along with increased endogenous thrombin potential (P = .02), without any changes in fibrin clot properties. Anti-β2GPI (hazard ratio, 4.38; 95% CI, 1.58-12.19) and aCL (hazard ratio, 4.70; 95% CI, 1.80-12.30) at a moderate or high titer were associated with IS during follow-up (n = 20; 1.9% per year). There were 23 major bleedings (2.1% per year) and 20 deaths (1.9% per year), which were not associated with aPLs.

CONCLUSION

Our study showed a relatively high prevalence of aPL positivity in AF patients, which was linked to an increased risk of IS/transient ischemic attack. This suggests that screening for aPL might help optimize anticoagulant therapy in such patients.