Effect of Vitamin D and parathyroid hormone levels on the coronary slow-flow phenomenon.

BACKGROUND: The presence of vitamin D, and parathyroid hormone receptors has been demonstrated in the vascular endothelium. Variations in vitamin D, and parathyroid hormone levels may affect coronary flow and cause the coronary slow-flow phenomenon (CSF). METHODS: We enrolled 93 patients who had undergone coronary angiography and had near-normal coronary arteries. Blood samples were taken to determine the calcium, phosphorus, 25-hydroxy vitamin D, and parathyroid hormone levels. Vitamin D deficiency was defined as a serum 25-hydroxy vitamin D level of less than 20 ng/mL. We divided the study population into two groups according to thrombolysis in myocardial infarction frame count (TFC) levels. RESULTS: Patients with TFC ≤27 were in the control group (n = 39), and those with TFC >27 were in the CSF group (n = 54). 25-Hydroxy vitamin D levels were similar in both groups: 17.5 [3.3-36.1] ng/ml in the CSF group and 15.2 [5.3-34] ng/ml in the control group (P = 0.129). When we analyzed TFC for each of the coronary arteries, we found a weak negative correlation between vitamin D level and TFC of the right coronary artery in the CSF group (r = -0.314, P = 0.021). Parathyroid hormone levels were similar in both groups: 48 [16-140] pg/ml in the CSF group and 52 [25-125] pg/ml in the control group (P = 0.297). CONCLUSION: The study failed to demonstrate a relationship between serum parathyroid hormone level and CSF. However, a weak negative correlation was found between vitamin D level and TFC of the right coronary artery.