Impact of First Medical Contact Time and Door-to-Balloon Time on In-Hospital Mortality in Patients with Acute ST-Segment Elevation Myocardial Infarction: A Retrospective Cohort Study Based on Monthly Chest Pain Center Data

Background : Timely reperfusion is critical for patients with acute ST-segment elevation myocardial infarction (STEMI). While door-to-balloon (D2W) time has been substantially optimized in chest pain centers, the impact of first medical contact (FMC) time—particularly its temporal dynamics and lag effects—remains insufficiently characterized. This study aimed to investigate the independent and combined effects of FMC and D2W time on in-hospital mortality in STEMI patients, and to analyze their temporal trends and lag effects. Methods : Monthly data from a certified chest pain center in China between January 2018 and December 2025 were retrospectively collected. Pearson correlation analysis was used to assess relationships between time indicators and mortality. Multiple linear regression was performed to evaluate independent effects. Autoregressive integrated moving average (ARIMA) models were constructed to analyze temporal trends. Distributed lag models (DLM) were applied to assess lag effects of FMC time on mortality up to 3 months. Sensitivity analysis was conducted for the COVID-19 pandemic period (2020–2022). Results : A total of 96 monthly data points involving 1,543 patients were included. FMC time showed a significant positive correlation with mortality (r=0.312, 95%CI: 0.115–0.486, P=0.002), while D2W time showed a weak correlation (r=0.183, 95%CI: -0.022–0.374, P=0.074). Multiple regression indicated FMC as an independent predictor of mortality (β=0.0018 per minute, 95%CI: 0.0007–0.0029, P=0.001), corresponding to a 0.11% increase in mortality per 60-minute FMC prolongation. D2W did not reach statistical significance (β=0.0006 per minute, 95%CI: -0.0002–0.0014, P=0.124). Time series analysis revealed that FMC was significantly prolonged during the COVID-19 pandemic, synchronizing with mortality fluctuations. The DLM model demonstrated that the impact of prolonged FMC on mortality persisted for up to 2 months (lag 1: β=0.0015 per minute, 95%CI: 0.0002–0.0028, P=0.026; lag 2: β=0.0011 per minute, 95%CI: 0.0001–0.0021, P=0.041), with a cumulative effect of 0.24% increase in mortality per 60-minute FMC prolongation over 3 months. Conclusions : FMC time is a critical time metric affecting in-hospital mortality in STEMI patients, with significant lag effects extending up to 2 months. D2W time did not demonstrate independent predictive value in this optimized chest pain center setting. These findings emphasize the need to strengthen pre-hospital emergency care systems and establish long-term monitoring of FMC time as a quality indicator.