Background: Serum alkaline phosphatase (ALP) has been shown to be a prognostic factor in several subgroups of patients due to its promotion of vascular calcification. However, the prognostic impact of serum ALP level in ST-segment elevation myocardial infarction (STEMI) patients with a relatively low calcification burden has not been determined. We aimed to investigate the association of ALP level measured at time of presentation on clinical outcomes in patients with STEMI requiring primary percutaneous coronary intervention (PCI).
Methods: A total of 1178 patients with STEMI undergoing primary PCI between 2007 and 2014 were retrospectively enrolled from the INTERSTELLAR registry and classified into tertiles by ALP level (<64, 65-82, or >83 IU/L). The primary study outcome was a major adverse cardiac or cerebrovascular event (MACCE), defined as the composite of all-cause death, non-fatal myocardial infarction, non-fatal stroke, and ischemia-driven revascularization.
Results: Median follow-up duration was 25 months (interquartile range, 10-39 months). The incidence of MACCE significantly increased as ALP level increased, that is, for the <64, 65-82, and >83 IU/L tertiles incidences were 8.7%, 11.7%, and 15.7%, respectively; p for trend = 0.003). After adjustment for potential confounders, the adjusted hazard ratios for MACCE in the middle and highest tertiles were 1.69 (95% CI 1.01-2.81) and 2.46 (95% CI 1.48-4.09), respectively, as compared with the lowest ALP tertile.
Conclusions: Elevated ALP level at presentation, but within the higher limit of normal, was found to be independently associated with higher risk of MACCE after primary PCI in patients with STEMI.