Benchmarking ambulance call-to-needle times for thrombolysis after acute myocardial infarction in Australia: a pilot study

BACKGROUND: Thrombolysis for patients with acute myocardial infarction (AMI) is of greatest benefit when treatment is commenced as soon as possible after symptom onset. The British Heart Foundation (BHF) recently set a benchmark recommending that eligible patients with AMI receive thrombolytic therapy less than 90 min after calling for medical assistance. AIMS: The purpose of this study was to compare the performance of an urban emergency service to this benchmark. A secondary objective was to determine whether patients treated outside this time were at a greater risk of mortality. METHODS: This study consisted of an explicit retrospective analysis of medical records for all patients who presented by ambulance to the Emergency Department (ED) of Western Hospital and received thrombolysis for AMI within 12 h of symptom onset. The study was conducted for the 18-month period between 1 January 1999 and 30 June 2000. Information collected included times of: (i) symptom onset, (ii) call for ambulance, (iii) ambulance response, (iv) transport to hospital and (v) thrombolysis, as well as final diagnosis and in-hospital mortality. For the purposes of this study, call-to-needle time (CTN) was defined as the time between calling the ambulance and commencement of thrombolytic therapy. RESULTS: One hundred and twenty-seven patients met the inclusion criteria. Median CTN was 81 min (range 42-279 min). Sixty-four per cent of patients were treated within the 90-min benchmark. The relative risk of mortality for patients treated outside the 90-min benchmark was 2.6 (95% CI 0.98-6.72). CONCLUSION: This study showed that the BHF benchmark for CTN was not being met for over one-third of patients in the study region, with potential impact on mortality after AMI. Further research is needed to establish: (i) whether there is relationship between longer transportation times and mortality, (ii) whether the findings of this study may be applied to other regions and (iii) what strategies might be employed to reduce CTN.