Gut-Derived Serum Lipopolysaccharide is Associated With Enhanced Risk of Major Adverse Cardiovascular Events in Atrial Fibrillation: Effect of Adherence to Mediterranean Diet.

BACKGROUND
Gut microbiota is emerging as a novel risk factor for atherothrombosis, but the predictive role of gut-derived lipopolysaccharide (LPS) is unknown. We analyzed (1) the association between LPS and major adverse cardiovascular events (MACE) in atrial fibrillation (AF) and (2) its relationship with adherence to a Mediterranean diet (Med-diet).

METHODS AND RESULTS
This was a prospective single-center study including 912 AF patients treated with vitamin K antagonists (3716 patient-years). The primary end point was a composite of MACE. Baseline serum LPS, adherence to Med-diet (n=704), and urinary excretion of 11-dehydro-thromboxane B2 (TxB2, n=852) were investigated. Mean age was 73.5 years; 42.9% were women. A total of 187 MACE (5.0% per year) occurred: 54, 59, and 74 in the first, second, and third tertile of LPS, respectively (log-rank test P=0.004). Log-LPS (hazard ratio 1.194, P=0.009), age (hazard ratio 1.083, P<0.001), and previous cerebrovascular (hazard ratio 1.634, P=0.004) and cardiac events (hazard ratio 1.822, P<0.001) were predictors of MACE. In the whole cohort, AF (versus sinus rhythm) (β 0.087, P=0.014) and low-density lipoprotein cholesterol (β 0.069, P=0.049) were associated with circulating LPS. Furthermore, Med-diet score (β -0.137, P<0.001) was predictive of log-LPS, with fruits (β -0.083, P=0.030) and legumes (β -0.120, P=0.002) negatively associated with log-LPS levels. Log-LPS and log-TxB2 were highly correlated (r=0.598, P<0.001). Log-LPS (β 0.574, P<0.001) and Med-diet score (β -0.218, P<0.001) were significantly associated with baseline urinary excretion of TxB2.

CONCLUSIONS
In this cohort of AF patients, LPS levels were predictive of MACE and negatively affected by high adherence to Med-diet. LPS may contribute to MACE incidence in AF by increasing platelet activation.