Determinants of Timely Prehospital Thrombolysis Administration Within a Pharmacoinvasive STEMI Network in Victoria,...

We aimed to describe the proportion of patients receiving prehospital thrombolysis (PHT) within 30 min of first medical contact (FMC) and identify factors associated with timely administration within a statewide pharmacoinvasive network.

We conducted a retrospective observational cohort study of consecutive adults (≥18 years) treated with paramedic-administered thrombolysis for suspected ST-segment elevation myocardial infarction (STEMI) between January 2018 and December 2023 using data obtained from the Victorian Ambulance STEMI Quality Initiative registry. Patients presenting in cardiac arrest were excluded. Multivariable logistic regression was used to identify system- and patient-level factors independently associated with FMC-to-PHT time, with delayed PHT defined as FMC-to-PHT greater than 30 min, and findings validated against a 60-minute threshold. Log-linear regression was used to estimate the percentage change in FMC-to-PHT time for each variable.

A total of 1440 patients were analyzed (median age, 65 years; 71.0% male). Overall, 32.5% of patients received PHT within 30 min of FMC (median 37 min [IQR 28-48]). Patients with delayed treatment (>30 min) were older and more likely to report mild pain severity (0-3/10), present after-hours, and have paramedics utilize clinical consultation prior to PHT administration. In the multivariable analysis, electrocardiogram (ECG) acquisition within 10 min of FMC was associated with reduced odds of delay (aOR 0.40, 95%CI 0.27-0.59), while mild pain severity was the strongest predictor of delayed PHT administration (aOR 2.08, 95% CI 1.44-3.01). Clinical consultation and after-hours presentations were also independently associated with increased odds of delay. In the log-linear analysis, mild pain severity (+14.8%), clinical consultation (+11.1%), and after-hours presentation (+9.2%) were associated with longer FMC-to-PHT times, whereas early ECG acquisition was associated with a 20% reduction. The findings were broadly consistent in the >60-minute model, with stronger associations for mild pain severity and after-hours presentation. Treatment times improved incrementally over the study period (aOR 0.83 per year, 95% CI 0.76-0.89).

Achieving FMC-to-PHT ≤30 min was challenging, and delays were associated with both patient presentation and system- and process-related factors. These findings suggest that opportunities exist to improve the timeliness of thrombolysis administration in pharmacoinvasive settings.