PURPOSE: The 2004 ACC/AHA guidelines for ST-elevation myocardial infarction recommend unfractionated heparin (UFH) with an initial bolus dose of 60 units/kg (maximum 4000 units) followed by a continuous intravenous infusion. Current data support the recommendation of an initial UFH infusion rate of 12 units/kg/hr (maximum 1000 units/hr), but data supporting an initial bolus are limited. We designed this study primarily to analyze the effect of an initial bolus of UFH on overall bleeding frequency and percent of initial (6 hour) aPTT values within goal range. Secondarily, to determine the effect of initial bolus on average percent of time in goal aPTT range and percent of aPTT levels within goal range at 24 and 48 hours.
METHODS: Retrospective cohort analysis of 2488 adult medical cardiac patients initiated on a weight-based nomogram of UFH with and without an initial bolus dose of 60 units/kg (no maximum) along with an initial continuous infusion rate of 12 units/kg/hr (no maximum).
RESULTS: Non-surgical bleeding rates did not differ between groups. No difference was found in percent of initial aPTT values within goal range whether an initial bolus dose was given or withheld. There also was no difference in average percent of time during the course of therapy within goal range or percent of patients having a goal aPTT within the goal range at 24 or 48 hours.
CONCLUSION: Initiation of UFH with an initial bolus of 60 units/kg followed by an initial continuous infusion rate of 12 units/kg/hr in medical cardiac patients does not increase bleeding rate or percent of initial aPTT values within goal range as compared to the same continuous infusion without an initial bolus.
CLINICAL IMPLICATIONS: Initiation of unfractionated heparin with an initial bolus in medical cardiac patients does not increase bleeding risk.
DISCLOSURE: Seth Bauer, None.