Abstract Background: ST-segment elevation myocardial infarction (STEMI) mandates rapid percutaneous coronary intervention (PCI) for optimal outcomes. The aim of this study was to assess our hospital practice for managing acute STEMI, identify processes associated with time delays, instrument changes to our acute STEMI management protocol and assess their effectiveness for improving our door-to-balloon time. Methods: We aimed to achieve this through the establishment of a quality improvement programme involving the cardiology and emergency departments. We analysed consecutive patients presenting with STEMI (April to September 2005 (group A) and the corresponding period in 2006 (group B), and compared patients presenting ‘in hours’ (0700 hours to 1800 hours (Monday to Friday)) versus ‘out of hours’ (all other times including public holidays). Results: In group A, 38 patients presented with a STEMI. Assessing time-to-treatment analysis, the median door to balloon time for primary PCI was significantly greater for ‘out of hours’ than ‘in hours’ (120 vs 67 min). The greatest time delay to PCI was from the PCI decision time to catheter laboratory arrival. Local changes were implemented to improve ‘out of hours’ times, including initiation of ‘Code AMI’. There were 59 patients in group B. We found that our changes led to a 29% improvement in ‘out of hours’ door-to-balloon time (median time 82 min, P = 0.005) with 69% being managed ≤90 min (P = 0.049) (group B). Conclusion: We have shown that ongoing review through a quality improvement programme improves door-to-balloon times, which is integral in the optimal management of patients with acute STEMI treated with primary PCI.