Hospital variability in use of anticoagulant strategies during acute myocardial infarction treated with an early invasive strategy.

Background-During a myocardial infarction, no single best approach of systemic anticoagulation is recommended, likely due to a lack of comparative effectiveness studies and trade-offs between treatments. Methods and Results-We investigated the patterns of use and site-level variability in anticoagulant strategies (unfractionated heparin [UFH] only, low-molecular-weight heparin [LMWH] only, UFH+LMWH, any bivalirudin) of 63 796 patients with a principal diagnosis of myocardial infarction treated with an early invasive strategy with percutaneous coronary intervention at 257 hospitals. About half (47%) of patients received UFH only, 6% UFH+LMWH, 7% LMWH only, and 40% bivalirudin. Compared with UFH, the median odds ratio was 2.90 for LMWH+UFH, 4.70 for LMWH only, and 3.09 for bivalirudin, indicating that 2 "identical" patients would have a 3- to 4-fold greater likelihood of being treated with anticoagulants other than UFH at one hospital compared with another. We then categorized hospitals as low-or high-users of LMWH and bivalirudin. Using hierarchical, multivariate regression models, we found that low bivalirudin-using hospitals had higher unadjusted bleeding rates, but the risk-adjusted and anticoagulant-adjusted bleeding rates did not differ across the hospital anticoagulation phenotypes. Risk-standardized mortality and risk-standardized length of stay also did not differ across hospital phenotypes. Conclusions-We found substantial site-level variability in the choice of anticoagulants for invasively managed acute myocardial infarction patients, even after accounting for patient factors. No single hospital-use pattern was found to be clinically superior. More studies are needed to determine which patients would derive the greatest benefit from various anticoagulants and to support consistent treatment of patients with the optimal anticoagulant strategy.