Crossover from Low Molecular Weight Heparin to Unfractionated Heparin in Non–ST-Segment Elevation Acute Coronary Syndromes Patients Managed Invasively

Background: Current guidelines strongly discourage crossing over between low molecular weight heparin (LMWH) and unfractionated heparin (UFH) in non–ST-segment elevation acute coronary syndromes (NSTE-ACS) patients. However, this is based on subgroup analysis recognized to be potentially biased and exploratory in nature.

Methods: Data was drawn from 11,710 consecutive NSTE-ACS patients treated invasively. Patients with heparin data were included. A comparative analysis was performed after the implementation of propensity score matching on the main cohorts: Patients who crossed from LMWH to UFH and those who did not. Primary outcome was defined as net adverse clinical endpoint (NACE) at 30 day: all-cause mortality, myocardial infarction (MI), target vessel revascularization (TVR), stent thrombosis (ST) and bleeding (a drop of 3 gr/dL or more in Hemoglobin). Each factor was also assessed separately.

Results: There were 1,529 “crossover” and 1,616 “no-crossover” patient, and the final analysis on matched patients included 1119 patients in each group. The two groups were well balanced by the propensity score modelling as there were no significant differences in age, sex, comorbidities and clinical presentation. There was no difference in the primary outcome between the groups: 5.7% crossover vs. 5.3% no-crossover, p=0.77; as well as in any factor assessed independently: all-cause mortality 1.2% vs. 0.9%, p=0.67; MI 0.3% vs. 0.4%, p=0.72; TVR 0.7% vs. 0.9%, p=0.77; ST 0.5% vs. 0.9%, p=0.40; major bleeding 4.1% vs. 3.6%, p=0.70, in the crossover vs. no-crossover group, respectively.

Conclusion: It appears that crossover from LMWH to UFH during the treatment course of NSTE-ACS patients is not associated with any 30 day net harm in terms of ischemic or bleeding risk. In light of the convenience advantages associated with upstream LMWH and downstream UFH utilization, it may be reasonable to consider crossing in NSTE-ACS patients, although dedicated trials are needed to further estimate the benefits and risks of this strategy.