Aims: The aim of the study was to investigate whether bivalirudin versus unfractionated heparin (UFH) reduces infarct size (IS) for primary percutaneous coronary intervention (PPCI) in large acute myocardial infarction (AMI).
Methods and results: This multicentre open-label trial randomised 78 patients undergoing PPCI for large AMI to bivalirudin or UFH. The primary endpoint was IS, assessed by cardiac magnetic resonance (CMR) five days after PPCI. Secondary endpoints included index of microcirculatory resistance (IMR), CMR-assessed microvascular obstruction (MVO) and ejection fraction, and biomarkers for thrombin activity and cell injury. No difference was observed in mean IS at five days (25.0±19.7 g for bivalirudin vs. 27.1±20.7 g for UFH; p=0.75). Early MVO was numerically lower with bivalirudin (5.3±5.8 g vs. 7.7±6.3 g; p=0.17), with no significant difference in ejection fraction at 90 days (54.6±12.0% vs. 49.1±12.1%; p=0.11). In the biomarkers, thrombin-antithrombin complexes were reduced by 4.8 ug/L over the first day for bivalirudin versus an increase of 1.9 ug/L in the heparin arm (p=0.0003). Acute IMR was lower (43.5±21.6 vs. 68.7±35.8 mmHg×s, respectively; p=0.014). In a planned interim analysis, an approximate 11% reduction in IS was observed with bivalirudin; the trial was discontinued for futility.
Conclusions: This study did not achieve its primary endpoint of significant infarct size reduction in PPCI by prolonged bivalirudin infusion compared to UFH, even though complete thrombin inhibition was achieved in the acute phase, with a lower myocardial microcirculation resistance at the end of the procedure.