Low vitamin D levels predict left atrial thrombus in nonvalvular atrial fibrillation

We determined the association between left atrial (LA) thrombus occurrence and a non-classic risk marker, plasma levels of vitamin D, in atrial fibrillation (AF) patients on continuous non-vitamin K antagonist oral anticoagulant (NOAC) therapy for ≥4 weeks. Low levels of plasma 25-hydroxy vitamin D (25-OHD) are predictive of fatal stroke. Vitamin D has anticoagulant effects on the coagulation cascade, which are indirectly targeted by NOAC therapy. The impact of plasma levels of vitamin D on the rate of LA thrombus detected by transesophageal echocardiography (TEE) in AF patients is unknown.

We enrolled 201 (133 female) AF patients who were using continuous NOAC therapy for ≥4 weeks. All patients underwent transthoracic and TEE examination. Serum concentrations of 25-OHD, C-reactive protein (CRP) levels, CHA₂DS₂-VASc scores and parameters, LA size, and left ventricle ejection fraction (LVEF) were examined before the TEE procedure. LA thrombus occurrence was independently associated with serum levels of 25-OHD (OR: 0.884; 95% CI: 0.839-0.932; P < 0.001), LA diameter (OR: 1.120; 95% CI: 1.038-1.209; P = 0.003), and LVEF(OR: 0.944; 95% CI: 0.896-0.995; P = 0.032). Dense spontaneous echo contrast (SEC) presence was also inversely associated with 25-OHD concentrations.

Low 25-OHD levels, as a non-classic risk factor, were independently and significantly associated with dense SEC and LA thrombus occurrence in AF patients under NOAC therapy, as well as LA enlargement and decreased LVEF. Further large-scale studies are needed to explain the role of vitamin D deficiency, or efficacy of replacement, on LA thrombus occurrence.