Pretreatment With Unfractionated Heparin in ST-Elevation Myocardial Infarction—A Propensity Score Matching Analysis

Abstract

Background: Patients with ST-segment elevation myocardial infarction (STEMI) are often pretreated with unfractionated heparin (UFH) before a primary percutaneous coronary intervention (PPCI). UFH pretreatment is intended to lessen the thrombotic burden, but there have been conflicting study findings on its safety and efficacy. We assessed the risks and benefits of UFH pretreatment with a retrospective analysis of registry data from the STEMI network of a German metropolitan region.

Methods: Data from patients with STEMI referred for PPCI from 2005 to 2020 were evaluated with an adjusted outcome analysis, including propensity score matching (PSM). The endpoints included the patency of the infarct-related artery (IRA) after PPCI, in-hospital mortality, access-site bleeding, and the peak creatine kinase (CK) level.

Results: We assessed data from 4632 patients with STEMI: 4420 (95.4%) were pretreated with UFH, and 212 (4.6%) were not. After PSM of 511 vs. 187 patients, the adjusted odds ratios for the various endpoints were (pretreatment vs. no pretreatment, with 95% confidence intervals): for impaired flow of the IRA, 1.01 [0.59; 1.74]; for in-hospital mortality, 1.46 [0.88; 2.42]; and for access-site bleeding, 0.59 [0.14; 2.46]. The peak creatine kinase levels were similar in the two groups (median, 1248.0 vs. 1376.5 U/L, estimated difference -134 [-611; 341]).

Conclusion: UFH pretreatment was less frequently performed in STEMI patients who had undergone cardiopulmonary resuscitation. UFH pretreatment was not associated with increased access-site bleeding, nor was it found to have significantly higher efficacy with respect to the relevant endpoints. The risks and benefits of UFH pretreatment should be weighed individually in each case, as evidence from high-quality clinical trials is lacking. Data from the existing literature suggest that no pretreatment is an option to be considered, as are certain alternative antithrombotic strategies.

Figure

Flow chart KIM, Kölner Infarkt Modell (Cologne Infarction Network); UFH, unfractionated heparin

eFigure 1

Standardized mean difference for continuous variables and mean difference for categorical variables before (orange) and after (blue) propensity score matching (PSM)

eFigure 2

Density of propensity scores in the group pretreated with unfractionated heparin (green) and the not pretreated group (red) before and after matching