The
heparin anti-Xa assay is affected by the use of direct oral
anticoagulants (DOACs) and is utilized in the management of intravenous
unfractionated heparin. Patients with non-ST-segment
myocardial infarction (
NSTEMI) receive intravenous
unfractionated heparin with prior administration of DOACs poses challenges given these laboratory abnormalities. On this background, we evaluate if an elevated
heparin anti-Xa assay may lead to the decision to delay
heparin in the management of
NSTEMI patients and the outcome of in-hospital mortality. This is a single-center chart review study with patients admitted between January 2019 and December 2020. Patients with a documented DOAC home medication and a diagnosis of
NSTEMI were included. Data was collected for
heparin anti-Xa levels at baseline, after 6 and 12 hours of hospitalization, in addition to the reason for the delay in the administration of
heparin. Statistical analysis included the determination of r-squared correlation and one-way ANOVA using GraphPad Prism 8.0. A total of 44 patients were divided into three groups based on baseline Xa levels of patients. Elevated Xa level was noted more in patients who were taking
apixaban.
Heparin infusion was delayed among this sub-group of patients. Elevated baseline
heparin anti-Xa levels were significantly improved after 12 hours. There was no correlation between elevated anti-Xa levels and activated partial thromboplastin time. No in-hospital mortality was observed among any of the subgroups. Collectively, this study demonstrates that the high sensitivity of
heparin anti-Xa assay to DOACs affect assay accuracy and result in elevated
heparin anti-Xa level with the use of DOACs resulting in delayed start of
heparin therapy in treating
NSTEMI patients.