Given both lipoprotein (Lp)(a) and vitamin D have been found to be associated with coronary heart disease (CHD) risk and a biochemical link between vitamin D and cholesterol on atherosclerosis has been proposed, we hypothesised there could exist an interaction between Lp(a) and vitamin D on the severity of CHD.

Lp(a) and 25-OH vitamin D were measured in the plasma of 348 consecutive patients (mean age 62.4±10.5 years; 56.3% male) undergoing coronary angiography at our Heart Center. A multivariate logistic regression model was used to estimate the odds ratios (ORs) of CHD.

Of these patients, CHD was identified in 212 (60.9%). A multivariable logistic regression model showed multivariable-adjusted ORs (95% CI) of CHD for patients with Lp(a)≧30mg/dl and vitamin D <10 ng/ml, Lp(a) <30mg/dl and vitamin D <10 ng/ml, and Lp(a)≧30mg/dl and vitamin D ≧10 ng/ml were 4.62 (2.04–10.46), 1.79 (1.00–3.17), and 1.70 (0.88–3.31), respectively, compared with those with Lp(a) <30mg/dl and vitamin D ≧10 ng/ml; the multivariable-adjusted ORs of a higher Gensini Score for the above three corresponding groups were 3.48 (1.84–6.60), 1.59 (0.96–2.65), and 1.55 (0.86–2.79), respectively. The interaction term between Lp(a) and vitamin D in each of the above two models was significant (p=0.004 and p=0.005, respectively).

Among patients undergoing coronary angiography, there existed an interaction between Lp(a) and vitamin D on the severity of CHD. Future cohort studies are warranted to confirm this finding.