Morphine can delay absorption of P2Y12-inhibitors in ST-elevation myocardial infarction (STEMI) patients, which has the potential to expose these patients to increased stent thrombosis risk after primary percutaneous coronary intervention (PPCI). Limited evidence exists for pharmacotherapeutic strategies aiming to mitigate this risk. We evaluated the impact of guideline-driven ‘routine’ glycoprotein IIb/IIIa antagonist (GPI) use in morphine-treated patients undergoing PPCI. A total of 3224 consecutive STEMI patients undergoing PPCI at a large tertiary cardiac center between 2012 and 2017 were evaluated. GPI use and outcomes before and after introduction of a local guideline were compared, and rates of definite stent thrombosis were identified at 24 h and 30 days. GPI use increased from 42.4% to 69.9% after the introduction of the new guideline. Stent thrombosis occurred in 1.3% (26/1947) pre-guideline and 0.6% (7/1244) post-guideline (P = .037). Of the 33 stent thrombosis cases, 90% (27/30) had received morphine, of whom 85.2% (23/27) had not received adjunctive GPI. Complete records for assessing 30-day bleeding rates were only available in 374 patients and, in this subset, there was no significant difference in rates of GUSTO moderate or severe bleeding before vs. after introduction of the local guideline (1.7% vs 2.8%; P = .47) although, in both cohorts combined, any GUSTO bleeding was observed more frequently in GPI-treated patients (21.8%) compared to those not receiving a GPI (10.0%; P = .002). In conclusion, routine GPI use in morphine-treated STEMI patients undergoing PPCI appears to protect against stent thrombosis. Large-scale studies are needed to establish the overall risk-benefit of GPI therapy in morphine-treated PPCI patients and to assess alternative strategies for preventing acute stent thrombosis in these patients
