In this five-year retrospective audit of patients presenting to a regional ED with STEMI requiring inter-hospital transfer for pPCI, the median D2BT was 117.5 min, which is just within the guideline-directed target of ≤ 120 min for non-PCI-capable hospitals. However, given that the median is a measure of central tendency, this necessarily means that a substantial proportion (47%) of our patients did not meet the international target, underscoring a need to optimize the acute STEMI pathway. In our analysis, the total D2BT was sub-categorized into three intervals to better resolve any causes of delay. Interval 1 (door-to-diagnostic ECG) was the only interval with a median value (18.0 min) above its target (≤ 10 min), with only 28.8% of patients achieving it. Despite being only 8.0 min above the target, considerable dispersion in the data was observed, with a quarter of all patients spending longer than 46.8 min in the ED before their diagnostic ECGs were obtained. As suggested by their median-normalized IQRs, the variability of Interval 1 was four times greater than that of Interval 2 (diagnostic ECG to arrival at PCI centre) and three times greater than that of Interval 3 (arrival at PCI centre to balloon inflation). Therefore, to improve the timeliness and consistency of Interval 1 at non-PCI-capable hospitals, we suggest that efforts be made to ensure the rapid triage of patients presenting to the ED with ischaemic-type symptoms while maintaining a low threshold of suspicion for acute coronary syndromes (ACS) in those presenting with atypical symptoms and a high-risk profile. In this regard, a forcing function implemented at patient registration could be beneficial, i.e., one requiring the documentation of chest pain and/or other symptoms suggestive of ACS, the presence of which would mandate automatic prioritization to ECG.

In contrast to Interval 1, the medians for Intervals 2 and 3 were within their targets and exhibited far less variability; yet a proportion of patients still failed to achieve these targets. Within the scope of the ED, the primary means of reducing Interval 2 is ensuring prompt ECG interpretation and the activation of emergency medical services (EMS) immediately upon making a diagnosis. Therefore, in patients triaged as potential ACS, it is critical to have a senior clinician available to rapidly interpret the ECG and make a timely decision on management. In circumstances where an on-site cardiologist is not immediately available, ECG data should be rapidly transmitted to the designated PCI centre for external review. Moreover, we hypothesize that delays in ECG diagnosis are often the result of an inappropriate reliance on quantitative serum biomarker testing, i.e., high-sensitivity troponin-T, when the initial diagnosis should be based on clinical presentation and ECG findings alone. To address this, clear protocols should be implemented to ensure prompt senior review when the clinical presentation and ECG findings suggest an ACS, before confirmatory biomarker testing is available. In cases where the ECG findings and/or the symptomatic presentation are equivocal, troponin testing should be considered as an adjunct to clinical diagnosis. Apart from these considerations, Interval 2 is largely dependent on patient transfer times. Given the unavoidable delays associated with EMS due to resource limitations and varying local conditions, there is an argument to be made for having a dedicated ambulance at regional non-PCI-capable centres, although the benefits for STEMI management and other critical transfer scenarios would need to be carefully weighed against the obvious resource implications. Regarding Interval 3, given that the MMUH already employs a single-call activation framework [9] for their cardiac catheterization laboratory (CCL), there is limited opportunity to improve its efficiency. Nevertheless, ensuring efficient communication between EMS and the PCI centre and/or real-time tracking of patient transfers should be prioritized to enable seamless transitions of care.

Our analysis relied on data collected by the MMUH pPCI registry, which included only a few key timepoints for the intervals comprising the total time spent at the transferring non-PCI-capable hospital. To obtain a more comprehensive understanding of the factors contributing to any delays in achieving the recommended D2BT, it would be beneficial for the transferring hospital to implement standardized reporting procedures for patients with suspected ACS to collect additional data points including the times of symptom onset, triage, first ECG, first positive ECG, EMS and CCL activation, and patient handover to EMS. This would facilitate more accurate internal review and the provision of data-driven feedback for ongoing quality improvement.

The effective management of STEMI patients begins before they reach the hospital. Encouraging individuals experiencing central chest pain to immediately call EMS (999/112) is a crucial first step, which can be facilitated through robust public education campaigns. This enables rapid pre-hospital assessment and direct patient transfer to a PCI-capable centre, thereby avoiding the delay associated with an unnecessary ED visit. This so-called ED “dwell time” is reported to be one of the most substantial and modifiable contributors to reperfusion delay, supporting the practice of ED bypass [10,11,12,13,14,15]. Encouragingly, the Irish Heart Attack Audit National Report for 2017–2020 reported an 81% rate of ED bypass, an improvement over previous years [16]. Nevertheless, the success of this approach hinges on the ability of EMS personnel to make informed decisions about patient routing. Despite protocols in place, 22 patients initially considered in our study were brought to the CHB ED despite having obtained a diagnostic ECG pre-hospital, either in the ambulance or a general practitioner’s office. As described in the Irish Heart Attack Audit National Report, key methods to facilitate ED bypass include ensuring emergency vehicles are equipped with 12-lead ECGs and that personnel are trained in its use and transmission of results, as well as the establishment of a “Code STEMI” freephone line to facilitate direct communication between EMS and the PCI centre [16].

This study should be interpreted in the context of several limitations. Firstly, our study was limited to a single transferring centre and may not be generalizable to other institutions. Furthermore, our study focused on D2BT and its sub-intervals and did not examine other relevant outcomes such as total ischaemic time, mortality, or morbidity. Moreover, our study relied on retrospective analysis of existing data, which may be subject to human error and incomplete documentation. In particular, our analysis was restricted to the timepoints documented in the MMUH pPCI registry, limiting our ability to resolve various factors that may have contributed to delays, especially those occurring at the transferring hospital, making a strong case for the internal standardization of documentation at all transferring hospitals.