Association between serum alkaline phosphatase and coronary artery calcification in a sample of primary cardiovascular prevention patients.

BACKGROUND AND AIMS

A high level of serum alkaline phosphatase (ALP) is associated with an increased risk of mortality and myocardial infarction. ALP hydrolyses inorganic pyrophosphate, which is a strong inhibitor of calcium phosphate deposition. The aim of this study was to determine whether ALP is associated with the coronary artery calcium score (CACS).

METHODS

We examined the association of CACS, assessed by computed tomography scanning, and ALP, in 500 patients consecutively recruited, free of cardiovascular disease. The CACS were categorized into two groups: no calcification (CACS = 0) (n = 187) and with calcification (CACS>0) (n = 313). ALP activity was divided into three tertile groups: low ALP level (<55 IU/L), intermediate (55-66 IU/L) and high ALP level (>66 IU/L).

RESULTS

The mean age was 60.9 ± 10.8 years, 49.6% of the patients were women. ALP ranged from 22 to 164 IU/L (mean 62.6 IU/L, SD 19.3). In univariate analysis, traditional cardiovascular risk factors, statin use (p = 0.001), and ALP (p = 0.001) were significantly associated with CACS. After adjusting for cardiovascular risk factors, only age (p = 0.001) and sex (p = 0.001) were independently associated with CACS. Compared to the tertile group with low levels of ALP, the intermediate tertile group [OR 2.11, 95% CI (1.12; 3.96), p = 0.02], as well as the high tertile group [OR 3.89, 95% CI (2.01; 7.54), p = 0.001)], was independently associated with CACS.

CONCLUSIONS

In patients free of cardiovascular disease, high ALP levels are positively and independently associated with coronary artery calcification. The metabolic pathway of ALP and inorganic pyrophosphate could be a target for new therapies against vascular calcification.