Objective Antiphospholipid (aPL) antibodies may activate platelets and contribute to vegetation growth and embolisation in infective endocarditis (IE). We aimed to determine the value of aPL as predictors of embolic events (EE) in IE.

Methods We studied 186 patients with definite IE (Duke-Li criteria, all types of IE) from the Nanc-IE prospective registry (2007–2012) who all had a frozen blood sample and at least one imaging procedure to detect asymptomatic or confirm symptomatic EE. Anticardiolipin (aCL) and anti-β₂-glycoprotein I (β₂GPI) antibodies (IgG and IgM) were assessed after the end of patients’ inclusion. The relationship between antibodies and the detection of EE after IE diagnosis were studied with Kaplan-Meier and Cox multivariate analyses.

Results At least one EE was detected in 118 (63%) patients (52 cerebral, 95 other locations) after IE diagnosis in 80 (time interval between IE and EE diagnosis: 5.9±11.3 days). At least one aPL antibody was found in 31 patients (17%).

Detection of EE over time after IE diagnosis was more frequent among patients with anti-β₂GPI IgM (log-rank P=0.0036) and that of cerebral embolisms, among patients with aCL IgM and anti-β₂GPI IgM (log-rank P=0.002 and P<0.0001, respectively).

Factors predictive of EE were anti-β₂GPI IgM (HR=3.45 (1.47–8.08), P=0.0045), creatinine (2.74 (1.55–4.84), P=0.0005) and vegetation size (2.41 (1.41–4.12), P=0.0014). Those of cerebral embolism were aCL IgM (2.84 (1.22–6.62), P=0.016) and anti-β₂GPI IgM (4.77 (1.79–12.74), P=0.0018).

Conclusion The presence of aCL and anti-β₂GPI IgM was associated with EE, particularly cerebral ones, and could contribute to assess the embolic risk of IE.