Prognostic value of alkaline phosphatase in patients with acute coronary syndromes

Objectives: The objective of the study was to investigate the association between alkaline phosphatase (AP) activity and prognosis of patients with acute coronary syndrome (ACS).

Design and methods: The study included 2134 patients with ACS undergoing percutaneous coronary intervention. All included patients had baseline AP measurements available. The receiver operating characteristic curve analysis showed that the best cut-off of AP for mortality prediction was 98.0U/L. Using this cut-off, patients were divided into two groups: a group with AP>98.0U/L (n=493) and a group with AP≤98.0U/L (n=1641). The primary endpoint was 3-year mortality.

Results: Overall, there were 229 deaths over the follow-up: 90 deaths among patients with an AP >98.0U/L and 139 deaths among patients with an AP≤98.0U/L (Kaplan-Meier estimates of 3-year total mortality, 19.5% and 9.3%, respectively; adjusted hazard ratio [HR]=1.37, 95% confidence interval [CI] 1.10-1.70, P=0.004 for each unit higher log AP). Cardiac deaths occurred in 157 patients: 66 deaths among patients with an AP>98.0U/L and 91 deaths among patients with an AP≤98.0U/L (Kaplan-Meier estimates of 3-year cardiac mortality, 14.3% and 6.0%, respectively; adjusted HR=1.32 [1.02-1.70], P=0.033, for each unit higher log AP). The C-statistic of the multivariable model with baseline variables was 0.836 [0.807-0.866] and it increased to 0.842 [0.814-0.874] after inclusion of AP (P=0.045).

Conclusions: In patients presenting with an ACS and treated with percutaneous coronary intervention, elevated AP activity is associated with increased risk of subsequent mortality.