Author + information
In 2015 the AHA/ACC recommended new heparin dosing guidelines for Non-ST elevation myocardial infarction (NSTEMI) patients to decrease the maximum initial bolus from 7500 units to 4000, and the initial infusion rate from 1500 u/hr to 1000. We implemented those guidelines, and as part of the National Cardiovascular Data Registry (NCDR) quality assurance process, compliance and the rates of bleeding were recorded. We analyzed the data to report the rates of compliance with the new recommendations, and determine if the lower heparin doses were associated with a decrease in bleeding events.
The study was conducted in a 546 bed tertiary care center. NCDR defines bleeding events as any of the following within 72 hours of starting heparin: 1) Hemoglobin (Hgb) drop >=3 g/dl; 2) Transfusion of red blood cells with Hgb > 8g/dl; 3) Procedural site intervention to address bleeding.
In 2014, 62% (78/125) received a heparin bolus >4000 units vs. 22% (23/105) in 2015. The relative risk (RR) of receiving a bolus >4000 units in 2014 vs. 2015 was 2.8 (95% CI [1.9,4.2]). The average drop in Hgb was similar: -1.9 +/- 1.6 in 2014 vs. -1.9 +/- 1.7 in 2015. The NCDR bleeding rate in 2014 (2.5%) was not significantly different from 2015 (5%), (Wilcoxon Rank-sum p=0.2). With the higher allowable heparin doses in 2014 the risk of a Hgb drop>=3 g/dl for the entire admission was not higher than in 2015 (RR 1.05. 95% CI [0.6,1.9]).
Conclusion and Plan
Implementation of the new recommendations was associated with 40% a decline in excessive heparin dosing for NSTEMI patients at our institution, but the rate of NDCR defined bleeding did not change significantly. The stable bleeding rate could be explained by the presence of confounders that were not recorded as part of the nursing quality assurance process, possibly a threshold effect in that the risk of bleeding in these patients does not directly correlate with the degree of PTT elevation, or an effect size too small to be detected by 230 patients. We are now conducting a detailed chart review to describe the demographics of all NSTEMI patients to compare those with an NDCR bleeding event and to patients who had a Hgb drop >=3 during hospitalization but did not meet NDCR criteria.