Relationship of Vitamin D, Spondyloarthritis Activity and Left Ventricular Systolic and Diastolic Function

Background/Objectives: Vitamin D insufficiency is common in patients with spondyloarthritis (SpA). We analyzed the relationship between vitamin D, disease activity, and left ventricular (LV) function in patients with SpA. Methods: A total of 298 patients with SpA and 57 healthy controls were enrolled. Serum vitamin D and laboratory cardiovascular risk factors were analyzed, and LV function was assessed by echocardiography. Vitamin D, the Ankylosing Spondylitis Disease Activity Score (ASDAS), and the Disease Activity Index for Psoriatic Arthritis (DAPSA) were examined for mutual correlations using univariate and multivariate linear regression models and were compared between groups. Results: Vitamin D levels did not differ between the SpA group and controls, although vitamin D supplementation was more frequent among SpA patients. Vitamin D was not associated with SpA activity. ASDAS and DAPSA were positively correlated with isovolumic relaxation time, and DAPSA was inversely correlated with peak early diastolic mitral annular velocity (e'), after adjustment for age, sex, metabolic factors, and/or therapy. Patients with insufficient serum vitamin D levels (<75 nmol/L) showed greater impairment of systolic and diastolic LV function and a diabetic-like lipid profile compared with those with sufficient vitamin D levels. The e' wave was positively correlated with vitamin D after controlling for confounding factors. These findings in patients with SpA are consistent with those previously reported in patients with psoriatic arthritis (PsA). Conclusions: Patients with SpA were characterized by vitamin D supplementation, increased disease activity parameters, and impaired LV function. SpA activity, independent of vitamin D, was associated with LV functional impairment, and vitamin D was associated with an increase in the e' wave after adjustment for confounding factors. However, causal inferences cannot be drawn from correlational analyses.