Association between increased serum alkaline phosphatase and the coronary slow flow phenomenon

Background: Despite marked advances in our understanding of the pathophysiology of the coronary slow flow phenomenon (CSFP), the exact mechanism remains unclear. Previous studies have suggested that CSFP might be associated with generalized atherosclerosis, endothelial dysfunction, and low-grade chronic inflammation. High serum alkaline phosphatase (ALP) levels are associated with vascular calcification, atherosclerotic disease, and an increased risk of cardiovascular events. However, the relationship between ALP and CSFP is unclear. Methods: We investigated 64 patients with angiographically proven CSFP and 50 with normal coronary flow. Serum ALP levels were measured in all studied individuals. Results: Serum ALP levels in patients with CSFP were significantly higher than those in the control group (705 +/- 17.1 vs. 61.9 +/- 16.1 U/L, P = 0.007). A positive association was observed (r = 0.42, P = 0.032) between serum ALP levels and the mean thrombolysis in myocardial infarction frame count (mTFC). Regression analysis showed a high serum ALP level was the only independent predictor of the mTFC (beta = 0309, P < 0.001). Moreover, our study showed that a serum ALP level > 67.5 U/L was a predictor of CSFP (sensitivity = 83.3%, specificity = 84.1%). Conclusions: Patients with CSFP show high serum ALP levels, which may be associated with the pathogenesis of CSFP. A high serum ALP level is a predictor of CSFP. Future studies are needed to clarify the role of ALP in patients with CSFP.