Characterization of prehospital time delay in primary percutaneous coronary intervention for acute myocardial infarction: Analysis of geographical infrastructure-dependent and - independent components

Background: Prehospital delay in reaching a percutaneous coronary intervention (PCI) facility is a major problem that prevents early coronary reperfusion in patients with ST-elevation myocardial infarction (STEMI). This study aimed to identify modifiable factors that contribute to the interval from symptom onset to arrival at a PCI-capable center, focusing on the geographical infrastructure-dependent and -independent factors. Methods We analyzed data from 603 STEMI patients who received primary PCI within 12 h of symptom onset in the Hokkaido Acute Coronary Care Survey. We used geographical information system software to calculate the minimum prehospital system time (min-PST), which represents the time required to reach a PCI facility based on geographical factors. We then subtracted the min-PST from the onset-to-door-time (ODT) to find the estimated delay-in-arrival-to-door (eDAD), which represents the time required to reach a PCI facility independent of geographical factors. Results The door-to-balloon-time (median [IQR]: 63 [44, 90] min) was shorter than ODT (median [IQR]: 104 [56, 204] min) regardless of the type of transportation. However, 44% of patients had more than 120 min ODT. The min-PST (median [IQR]: 3.7 [2.2, 12.0] min) varied widely among patients, with a maximum of 156 min. Prolongation of the eDAD (median [IQR]: 89.1 [49, 180] min) was associated with older age, absence of a witness, onset at night, no EMS call, and transfer via a non-PCI facility. If the eDAD was zero, the ODT was projected to be less than 120 min in more than 90% of patients. Conclusions The contribution of geographical infrastructure-dependent time in prehospital delay was substantially smaller than that of geographical infrastructure-independent time. Intervention to shorten eDAD by focusing on factors such as older age, absence of a witness, onset at night, no EMS call, and transfer via a non-PCI facility appears to be an important strategy for reducing ODT in STEMI patients. Additionally, the eDAD may be useful for evaluating the quality of STEMI patient transports in areas with different geographical conditions.