BACKGROUND: Timely reperfusion in ST-segment elevation myocardial infarction (STEMI) improves outcomes. System delay is that between first medical contact and reperfusion therapy, comprising prehospital and hospital components. This study aimed to characterize prehospital system delay in Singapore. METHODS: A retrospective chart review was performed for 462 consecutive STEMI patients presenting to a tertiary hospital from December 2006 to April 2008. Patients with cardiac arrest secondarily presented were excluded. For those who received emergency medical services (EMS), ambulance records were reviewed. Time intervals in the hospital were collected prospectively. The patients were divided into two equal groups of high/low prehospital system delay using visual binning technique. RESULTS: Of 462 patients, 76 received EMS and 52 of the 76 patients were analyzed. The median system delay was 125.5 minutes and the median prehospital system delay was 33.5 minutes (interquartile range [IQR]=27.0, 42.0). Delay between call-received-by-ambulance and ambulance-dispatched was 2.48 minutes (IQR=1.47, 16.55); between ambulance-dispatch and arrival-at-patient-location was 8.07 minutes (IQR=1.30, 22.13); between arrival-at- and departure-from-patient-location was 13.12 minutes (IQR=3.12, 32.2); and between leaving-patient-location to ED-registration was 9.90 minutes (IQR=1.62, 32.92). Comparing patients with prehospital system delay of less than 35.5 minutes versus more showed that the median delay between ambulance-dispatch and arrival-at-patient-location was shorter (5.75 vs. 9.37 minutes, P<0.01). The median delay between arrival-at-patient-location and leaving-patient-location was also shorter (10.78 vs. 14.37 minutes, P<0.01). CONCLUSION: Prehospital system delay in our patients was suboptimal. This is the first attempt at characterizing prehospital system delay in Singapore and forms the basis for improving efficiency of STEMI care.

INTRODUCTION: Early reperfusion of ST-segment elevation myocardial infarction (STEMI) results in better outcomes. Interventions that have resulted in shorter door-to-balloon (DTB) time include prehospital cardiovascular laboratory activation and prehospital electrocardiogram (ECG) transmission, which are only available for patients who arrive via emergency ambulances. We assessed the impact of mode of transport on DTB time in a single tertiary institution and evaluated the factors that affected various components of DTB time. METHODS: We conducted a retrospective cohort study using registry data of patients diagnosed with STEMI in the emergency department (ED) who underwent primary percutaneous coronary intervention. We compared patients who arrived by emergency ambulances with those who came via their own transport. The primary study end point was DTB, defined as the earliest time a patient arrived in the ED to balloon inflation. As deidentified data was used, ethics review was waived. RESULTS: A total of 321 patients were included for analysis after excluding 7 with missing data. The mean age was 61.4±11.4 years old with 49 (15.3%) females. Ninety-nine (30.8%) patients arrived by emergency ambulance. The median DTB time was shorter for patients arriving by ambulance versus own transport (52min, interquartile range [IQR] 45-61 vs 67min, IQR 59-74; CONCLUSION Arrival via emergency ambulance was associated with a decreased DTB for STEMI patients compared to arriving via own transport. There is a need for public education to increase the usage of emergency ambulances for suspected heart attacks to improve outcomes.
Aged ; Ambulances ; Angioplasty, Balloon, Coronary ; Female ; Humans ; Middle Aged ; Percutaneous Coronary Intervention ; Retrospective Studies ; Time Factors