The current study demonstrated that implementation of a modified cardiac triage protocol for early identification and treatment of patients with STEMI in the emergency care setting could significantly shorten the median DTE time and increase the achievement rate of DTE time less than 10 minutes. Moreover, median DTB time was also significantly reduced. Further investigation also revealed a significant reduction in the incidence of DTE time over 10 minutes among patients belonging to a low triage category (i.e., III, IV, or V) after intervention.
DTB is a survival chain comprising early ECG with prompt interpretation, early catheterization lab activation, an expedited response to activation, and rapid reperfusion . Although multiple factors would affect DTB time, a previous study has shown a stronger association of DTB time with door-to-activation time compared to that with activation-to-laboratory and laboratory-to-balloon times . Timely ECG is crucial to the identification of patients with STEMI for prompt primary PCI. The American Heart Association (ACC/AHA) management guideline for patients presenting with symptoms of cardiac ischemia has indicated a DTB time of less than 10 minutes as a standard for acceptable emergency medical practice . Hence, various efforts have been made to shorten the DTE time, including designation of an ECG technician and equipment for triage ECG, organization of triage education, improvement of triage disposition, and data feedback . Although assigning a technician and ECG equipment to the conduction of triage ECG has been shown effective for reducing DTE time [8, 17, 23–25], indiscriminate ECG screening without a patient interview by an experienced emergency physician has raised the concern of increasing workload among nursing staff as well as the possibility of low cost-effectiveness . Indeed, a previous study has reported a 30% increase in ECG workload after implementation of a triage ECG program . By combining the strategies of cardiac triage and triage ECG, Coyne et al. have shown a reduction of DTE time by 39% (i.e., from 23 to 14 minutes) and DTB by 12% (from 85 to 75 minutes). Taking into consideration the downsides of triage ECG, the current study aims at investigating the impact of cardiac triage per se on DTE time reduction.
Our cardiac triage protocol included the triage nurse’s early identification of patients with a possible ischemic heart disease by labeling the patients a red warning tag that alerted the emergency medical personnel (i.e., emergency physicians, residents, or nurse practitioners) of the need for prompt history-taking and placing their medical records in a designated box for expedited management. For patients presenting with a history suggestive of coronary heart disease, prompt ECG was acquired. In this way, indiscriminate ECG screening was avoided. This approach also eliminated the necessity of assigning nursing staff, space, and ECG equipment as required for triage ECG. This is of particular clinical importance because overcrowding in the ED is a critical issue worldwide [26, 27] and efficient utilization of medical manpower remains one of the formidable challenges to healthcare organizations. Moreover, although the proportion of patients (8.84%) receiving ECG in our ED in the post-intervention group was not increased compared with that in the pre-intervention group (8.83%), our study demonstrated that the achievement rate of DTE < 10 minutes and DTB < 90 minutes were improved from 78.9–95% (20.4%) and 68.4–83.3% (21.8%), respectively (both p < 0.05). The findings, therefore, indicate significant reductions in both DTE and DTB without increasing the ECG workload.
Furthermore, through adopting the concept of mass casualty triage , the triage nurse labeled the patients suspected of experiencing acute coronary syndrome with a red tag and placed their medical records in a designated box to expedite medical attention by emergency clinicians in a busy and noisy environment as well as the acquisition of an ECG for early diagnosis, thereby enabling prompt primary PCI for confirmed cases of STEMI.
As a DTE time over 10 minutes is an indicator of unacceptable emergency medical practice , we investigated the effectiveness of our interventions for reducing the DTE time by selecting the predictors previously reported to be related to DTE > 10 minutes, including the female gender , STEMI without chest pain [10, 15], relatively non-severe initial presentations (i.e., Triage Category III, IV, V) , and walk-in patients , for analysis. Among them, DTE time of STEMI patients assigned into a low (i.e., less severe) triage category was significantly improved after intervention. The designation of triage levels to patients with cardiac ischemic symptoms by triage nurses might be affect by multiple factors, including patient’s characteristics, acute myocardial infarction volume, or subjective experience of triage nurses [22, 29]. Clare et al. has reported that up to one third of patients with STEMI could have an initial non-severe presentation (i.e., a low triage score), resulting in prolonged DTE and DTB times . Albeit not as high as the proportion previously reported, there were still 17% of STEMI patients being assigned to a low triage category in our study. Although there was no significant difference in the proportion of patients with a low triage score between pre- and post-intervention groups in the current study as well as in a previous triage ECG report , the percentage of patients with STEMI assigned with a low triage score decreased significantly from 90% (9 of 10) to 10% (1 of 10) (p < 0.01) after cardiac triage implementation.
Despite the lack of statistical significance, DTE > 10 minutes in female gender and walk-in patients were decreased after our intervention. Female gender has been reported as a strong independent predictor of delayed ECG acquisition in several literature reviews [12, 22, 30]. Possible reasons for delayed ECG in females include atypical symptom presentation and the concern for ECG acquisition-related violation of personal privacy to which a sufficient number of female triage nurses has been reported to be a possible solution . During the post-intervention period, all female patients undergoing cardiac triage received ECG performed by female nurse practitioners so that the influence of personal privacy on DTE time could be minimized. Additionally, the mode of arrival may also contribute to a prolonged DTE time . Literature review showed that patients with walk-in arrival are more likely to be designated into a low triage category compared with those arrived by ambulance , contributing to a possible delay in receiving medical attention under the circumstances of ED overcrowding. This is supported by our study in which all STEMI patients with DTE > 10 minutes arrived at the ED on foot in both pre-and post-intervention groups. Utilizing cardiac triage with a red warning tag could expedite ECG examination for patients presenting with ischemic cardiac symptoms even if they belong to a low triage category.
There were 14% and 6% of STEMI patients without chest pain in our pre- and post-invention groups, respectively. The figure was within the range of 9–30% previously reported [15, 33]. Our results showed no significant difference in the rate of DTE time < 10 minutes before and after implementation of the cardiac triage program (37.5% vs. 50%, respectively), indicating no notable benefit in this particular patient population. One of the possible reasons could be atypical initial presentations of STEMI such as general discomfort, dizziness or weakness in some of the patients, which have not been included in the AHA screening guidelines . Further emendations of the cardiac triage protocol may be necessary to expand the criteria for inclusion. Nevertheless, the number of patients with atypical STEMI presentations was too small to arrive at a robust conclusion.
The present study had its limitations. Firstly, the statistical power and reliability of our results were limited by the relatively small number of patients, which was due to the single center nature of the current study instead of a nationwide investigation. Besides, STEMI patients usually comprise only a minor portion of patients visiting the ED during the study period. Second, because the modified cardiac triage protocol is aimed at expediting STEMI patient management in a high-volume emergency care setting as a quality improvement strategy, its feasibility and effectiveness in other ED settings remain to be validated. Third, the accuracy of data acquisition may be hampered by ambiguous symptom descriptions in medical records, for which experts in the quality control team were recruited as reviewers to categorize the nature of those symptoms to minimize the impact of this potential confounder.