a b s t r a c t

Background: The boarding of patients in the emergency department consumes nursing and physician resources, and may delay the evaluation of new patients. It may also contribute to poor cardiovascular outcomes in patients with acute coronary syndrome (ACS). This study analyzed the relationship between the delay in coronary care unit (CCU) admission and the clinical outcomes of patients with ACS with non-ST-segment elevation (NSTE-ACS). Methods: Patients were divided into 2 groups according to the CCU waiting time (b 12 h and N 12 h). Outcome var- iables including in-hospital mortality, gastrointestinal bleeding and stroke during hospitalization, and duration of hospital stay were compared between the 2 study groups. We used the GRACE risk scores to classify disease se- verity of the study patients for stratifying analysis.

Result: A difference was found in the outcome of gastrointestinal bleeding. Among those with GRACE risk scores of b 3 (low mortality risk) and 3 (high mortality risk), 5% and 3.1% of patients developed gastrointestinal bleeding, respectively, with CCU waiting time of N 12 h compared to CCU waiting time of b 12 h. However, there was no significant statistical difference (P = 0.065 and 0.547). In addition, there were no significant differences in the in-hospital mortality rate, incidence of stoke, and duration of hospital stay between the 2 groups.

Conclusion: There was no significant difference in the clinical outcomes of NSTE-ACS patients without profound shock between those with CCU Waiting times of b 12 and N 12 h. If necessary, CCU admission should be prioritized for patients whose hemodynamic instability or respiratory failure.

(C) 2017

Introduction

Most patients with acute coronary syndrome (ACS) are initially treated in the emergency department (ED). ACS refers to a group of clin- ical symptoms compatible with acute myocardial ischemia, including unstable angina, Non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction . Based on the American Heart Association (AHA) guidelines, Primary percutaneous coronary intervention is the preferred treatment for patients with STEMI [1]. Therefore, most affected individuals receive Primary PCI before Admission to the coronary care unit . However, patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) may stay in the ED without receiving primary PCI while awaiting CCU admission. ED crowding has become a major barrier in giving timely emergency care to patients worldwide [2,3]. Patient boarding in the ED consumes the nursing staff and physician resources and may delay the evaluation of new patients. ED crowding may also contribute to poor cardiovascular outcomes in patients who present

* Corresponding author at: No. 123, Dapi Rd., Niaosong Dist., Kaohsiung 833, Taiwan.

E-mail address: [email protected] (C.-J. Li).

with ACS [4]. One important cause of ED crowding is the inability to move admitted patients from the ED to an inpatient bed [5,6]. This study analyzed the relationship between the delay in CCU admission delay and clinical outcome of patients with NSTE-ACS. The results might help us realize the potential risks of CCU admission delay in pa- tients with NSTE-ACS and identify high-risk patients who need earlier CCU admission.

Materials and methods

Study design

This retrospective study was approved by the Chang Gung Medical Foundation Institutional Review Board. Based on the understanding that all data in the patient and physician records used in the analyses has been anonymized and de-identified, the ethics committee approved the research protocol with a waiver of informed consent.

Study setting

This study was conducted across the Kaohsiung Chang Gung Memo- rial Hospital, a Tertiary teaching hospital, with 2715 beds including 1388

http://dx.doi.org/10.1016/j.ajem.2017.02.049

0735-6757/(C) 2017

C.-C. Chen et al. / American Journal of Emergency Medicine 35 (2017) 1078-1081 1079

beds in the adult general ward and 203 beds in the adult intensive care unit (ICU) including 12 beds in the CCU. Over 130,000 patients visit the emergency department (ED) annually. Around 400 ACS patients are treated each year. While STEMI patients received primary PCI as the re- perfusion therapy and were admitted to the CCU directly, NSTE-ACS pa- tients often boarded in the ED awaiting CCU admission. These patients were referred to one particular ED observation unit for critical patients with continuous Electrocardiography and blood pressure moni- tors, and a Pulse oximeter. A cardiologist was routinely consulted for confirming the diagnosis and suggesting treatment options. An emer- gency physician (EP) provided round-the-clock care for these patients. If there were major changes in the patient’s condition, the cardiologist could be consulted again for a second survey.

Participants

Patient data were obtained from the ACS registry of the Kaohsiung Chang Gung Memorial Hospital from January 2011 to December 2013. Patients aged >= 18 years who presented at the ED, fulfilled the diagnostic criteria of ACS, and were admitted to the CCU, were included in the study. We excluded patients who developed STEMI (ST segment eleva- tion of N 1 mm in 2 contiguous limb leads and 2 mm in precordial leads, or the presence of new onset Left bundle branch block) [7], and those who required insertion of an intra-aortic balloon pump (IABP), or extra- corporeal membrane oxygenation (ECMO) due to hemodynamic insta- bility refractory to medication treatment. Patients with shortened life- span in the ED, and patients with mild symptoms who were directly ad- mitted to the general ward were also excluded.

Variables

Independent variables including basic patient characteristics, clinical information, and factors of GRACE risk scores [8,9] were obtained from the ACS registry of the Kaohsiung Chang Gung Memorial Hospital. Pa- tients were divided into 2 groups according to the CCU waiting time (b 12 h and N 12 h). The CCU waiting time was defined as the time inter- val from patient registration to patient admission to the CCU. The GRACE risk scores were developed for predicting mortality for the entire spectrum of ACS. The predictor variables included age, heart rate, systol- ic blood pressure, creatinine level, Killip class of heart failure, cardiac arrest at admission, ST-segment deviation, and cardiac enzyme levels [8,9]. We used the GRACE risk scores to classify disease severity of the study patients for stratifying analysis. Outcome variables included in- hospital mortality, gastrointestinal bleeding and stroke during hospital- ization, and hospital length of stay.

Data analysis

For continuous variables, the data were summarized as mean and standard deviation (SD) and analyzed by a Student’s t-test. The CCU waiting time and duration of hospital stay showed non-normal distribu- tions, and medians and nonparametric Mann-Whitney U tests were used to describe and evaluate their associations. The distributions of cat- egorical variables were summarized as numbers and percentages, and a chi-square test was used to evaluate the associations between outcome groups. In the multivariate analyses, binary logistic regression models were applied to assess the effect of the CCU waiting time of N 12 h on documented patient outcomes to adjust for the potential confounding factors including patient’s age, sex, and GRACE risk scores. Effects

Result

Patient demographics

During the study period, 770 adult patients who had developed NSTE-ACS visited the ED. Twenty-eight patients left the ED after short- term treatment without admission. Two hundred and five patients with mild symptoms were admitted to the general ward directly with- out CCU admission. Only 497 who were admitted to the CCU were in- cluded in the study. The median CCU waiting time of the 497 patients was 11.6 h. Therefore, we divided the patients into the following 2 study groups: those with CCU waiting time b 12 h and those with CCU waiting time N 12 h. There was no significant difference in patient char- acteristics between the 2 study groups (Table 1).

Outcome

Overall, the rate of hospital mortality, gastrointestinal bleeding, and stroke was 7.2%, 11.5%, and 14.9%, respectively. To understand the effect of CCU waiting of N 12 h on the outcome of the patients with different levels of disease severity, stratifying analysis was conducted according to the GRACE risk scores (b 3 and 3). In the subgroup analysis, a differ- ence was found in the outcome of gastrointestinal bleeding. Among those with GRACE risk scores of b 3 and 3, 5% and 3.1% of patients devel- oped gastrointestinal bleeding, respectively, with CCU waiting time of N 12 h compared to CCU waiting time of b 12 h. However, there was no significant difference. In addition, there was no significant difference in the in-hospital mortality rate, incidence of stoke, and duration of hos- pital stay (Fig. 1). To simultaneously control for potential confounding factors including age, sex, and GRACE risk scores at the same time, a lo- gistic regression model was conducted. Patients with CCU waiting time of N 12 h still had no significant statistical difference in the incidence of in-hospital mortality, gastrointestinal bleeding, and stroke (Table 2).

The major causes of mortality were ACS and sepsis. Two patients died of gastrointestinal bleeding in the group with CCU waiting time of N 12 h; no patient in the group with CCU waiting time of b 12 h died (Fig. 2).

Discussion

Based on previous studies, the care provided in the ED cannot re- place that provided in the ICU, although the ED can temporarily accom- modate critically ill patients [10,11]. Hung et al. recently reported that delayed ICU admission is associated with a higher mortality probability and additional resource expenditure for mechanically ventilated

Table 1

Baseline demographic.
Patient number	b12 h 256	N 12 h 241	P-value
Male	178 (69.5%)	171 (71.0%)	0.729
Age	68.2 +- 12.11	69.6 +- 12.06	0.186
Heart rate	90.2 +- 23.44	92.3 +- 24.23	0.322
Systolic blood pressure (mm Hg)	141.0 +- 37.10	145.6 +- 37.78	0.173
Creatinine (mg/dL)	3.1 +- 4.42	3.4 +- 3.63	0.387
ST-segment deviation on EKG	78 (30.5%)	69 (28.6%)	0.654
Cardiac enzyme elevation	222 (86.7%)	195 (80.9%)	0.078
Killip class I	116 (45.3%)	107 (44.4%)	0.205
II	52 (20.3%)	59 (24.5%)
III	71 (27.7%)	68 (28.2%)
IV	17 (6.6%)	7 (2.9%)
Grace level	0.400
I	68 (26.6%)	52 (21.6%)

were estimated in terms of adjusted odds ratios (aORs) and the corre-	II	71 (27.7%)	75 (31.1%)
sponding 95% confidence intervals (CIs). Results were considered statis-	III	117 (45.7%)	114 (47.3%)

tically significant for a two-tailed P b 0.05. The statistical analysis was conducted using SPSS version 12.0 (SPSS, Chicago, IL) for Windows.

ventilator support	86 (33.6%)	81 (33.6%)	0.997
Percutaneous coronary intervention	210 (82.0%)	192 (79.7%)	0.503

1080 C.-C. Chen et al. / American Journal of Emergency Medicine 35 (2017) 1078-1081

Fig. 1. The in-hospital mortality (A), incidence of gastrointestinal bleeding (B) and stroke (C), and medians of duration of hospital stay (D) in patients with CCU waiting time of b12 h and

N 12 h in Grace risk scores of b 3 and =3.

Table 2

The association between CCU waiting time of b12 h and patient outcome by logistic re- gression analysis

	ED length of stay b 12 h	ED length of	stay N 12 h
	Reference	aOR	95% CI
In-hospital mortality	1	0.7	0.44-1.78
Gastrointestinal bleeding	1	1.5	0.82-2.60
Stroke	1	0.9	0.53-1.43

patients in the ED. The recommended benchmark ICU waiting time is no N 4h [12]. Unlike other critical patients who need persistent intensive treatment, most patients with ACS need major treatments that include antithrombotic and Antiplatelet therapy with continuous ECG monitor- ing, except for those who develop pulmonary edema with respiratory failure or cardiogenic shock and need a ventilator, IABP, or ECMO for life support. A previous study has suggested that the CCU should usually be reserved for patients with moderate (21% or more, depending on the

patient’s age) probability of having an acute myocardial infarction, un- less the patients need intensive care for other reasons [13]. However, the study focused on patients who developed chest pain with suspected ACS; the effect of the CCU admission delay on the patient’s clinical out- come was not discussed in detail. In our study, we analyzed the relation- ship between the CCU waiting time and clinical outcomes of patients who developed NSTE-ACS without profound shock. We found that delay of N 12 h in CCU admission did not increase the in-hospital mortal- ity rate, gastrointestinal bleeding and stroke incidence during hospital- ization, or duration of hospital stay.

Based on the 2014 AHA/American College of Cardiology (ACC) guidelines for the management of patients with NSTE-ACS [14], patients with continuing angina, hemodynamic instability, uncontrolled arrhythmias, or a large myocardial infarction should be admitted to the CCU. The nurse-to-patient ratio should be sufficient to provide

1) continuous ECG rhythm monitoring, 2) frequent vital sign and

mental status assessment, and 3) rapid cardioversion and defibrillation. In our study, the ED observation unit offered continuous ECG and blood

Fig. 2. The distribution of causes of mortality in patients with CCU waiting time of b12 h and N 12 h.

C.-C. Chen et al. / American Journal of Emergency Medicine 35 (2017) 1078-1081 1081

pressure monitoring and pulse oximetry. The nurse-to-patient ratio was 4-5, mildly higher than the ratio of 2-3 in the CCU. One EP who provid- ed round-the-clock care and could perform rapid cardioversion or defi- brillation was available. One cardiologist was routinely consulted for diagnosis confirmation and patient follow-up, if necessary. Considering that none of the patients needed IABP or ECMO for life support in our study, we believed that the workload of the nursing staff in the ED ob- servation unit might be close to that in the CCU. On the other hand, the round-the-clock nature of the EP’s shift might have facilitated more timely care to the patient. These reasons might explain why a sig- nificant difference was not observed in the patient outcome between the two study groups.

Prolonged CCU waiting time might still have some disadvantages. Although not statistically significant, patients with CCU waiting time of N 12 h had mildly higher gastrointestinal bleeding incidence than those with CCU waiting time of b 12 h; two patients from the former group died of gastrointestinal bleeding. Recent studies declared that is- chemic event reduction using more potent antithrombotic and anti- platelet therapy was achieved at the expense of more bleeding [15, 16]. The AHA/ACC guidelines for the management of patients with un- stable angina/NSTEMI emphasize the importance of benefit-and-risk balance [14]. The possible reasons why patients with longer CCU waiting times develop more gastrointestinal bleeding might include 1) the low level of EP’s familiarity on antithrombotic and antiplatelet ther- apy and 2) fewer nursing staff members, which might make frequent checking of coagulation profile and catching early mild bleeding symp- toms, such as bleeding gums, difficult. Considering that bleeding is asso- ciated with increased cardiovascular mortality [17,18], additional efforts are needed to improve performance in the ED and optimize the clinical outcomes of patients with NSTE-ACS who have a high risk for bleeding.

Conclusion

There was no significant difference in the clinical outcomes of NSTE- ACS patients without profound shock between those with CCU waiting times of b 12 and N 12 h. If necessary, CCU admission should be priori- tized for patients whose hemodynamic instability or respiratory failure.

Limitations

The study has several limitations. First, it was a single center study with a relatively small sample size. Second, as this was retrospective study, there may have been some confounding factors that were not well controlled. Third, we were unable to determine the patients’ out- comes after discharge. Fourth, practice patterns in Taiwan are remark- ably different in some ways compared with that in the US and other Western countries, especially with respect to decisions related to

admission. We believe that it may influence the interpretation of our re- sult by other medical systems.

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