Original Contribution

Contents lists available at ScienceDirect

American Journal of Emergency Medicine

journal homepage: www. elsevier. com/ locate/ajem

The first-Door-to-balloon time delay in STEMI patients undergoing Interhospital transfer?

Jeong Ho Park, MD ^a,b, Ki Ok Ahn, MD, PhD ^a,?, Sang Do Shin, MD, PhD ^a,b, Won Chul Cha, MD ^a,c,

Hyun Wook Ryoo, MD, PhD ^a,d, Young Sun Ro, MD, DrPH. ^a, Taeyun Kim, MD, PhD ^a,e

^a Laboratory of Emergency Medical Service, Seoul National University Hospital Biomedical Research Institute, Seoul, Korea

^b Department of Emergency Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea

^c Department of Emergency Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea

^d Department of Emergency Medicine, Kyungpook National University College of Medicine, Daegu, Korea

^e Department of Emergency Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea

a r t i c l e i n f o

Article history:

Received 13 October 2015

Received in revised form 18 December 2015

Accepted 20 December 2015

a b s t r a c t

Background: Interhospital transfer delays for ST-elevation myocardial infarction patients requiring Primary percutaneous coronary intervention may be shortened by improved regional care systems. We evaluated the transfer process and first door-to-balloon (D1toB) time in STEMI patients who underwent interhospital transfer for Primary PCI.

Methods and Results: We evaluated the D1toB time in 1837 patients who underwent interhospital transfer for primary PCI from the Cardiovascular Disease Surveillance program in Korea. Only 29.3% of patients had a D1toB time less than 120 minutes, as recommended by the American College of Cardiology Foundation/American Heart Association guidelines for the management of STEMI. After adjusting for potential confounders, chest pain at presentation (adjusted odds ratio [AOR], 2.06; 95% confidence interval [CI], 1.18-3.83), transfer to a PCI center with an annual PCI volume greater than 200 (AOR, 1.35; 95% CI, 1.04-1.74), and higher urbanization level (AOR, 2.01 [95% CI, 1.40-2.91], for urban areas; AOR, 3.70 [95% CI, 2.59-3.83], for metropolitan areas) showed beneficial effects on reducing the D1toB time. The median length of stay in the referring hospital (D1LOS) and interhospital transport time were 50 (interquartile range [IQR], 30-100) minutes and 32 (IQR, 20-51) minutes, respectively. The median time interval from the door of the receiving hospital to balloon insertion was 55 (IQR, 40-79) minutes. Conclusions: Patients with STEMI undergoing interhospital transfer did not receive definite care within the recommended therapeutic time window. Delays in the transfer process (length of stay in the referring hospital and interhospital transport time) were major contributors to the delay in the D1toB time.

(C) 2015

Introduction

Background

Several randomized trials have reported that in patients with ST- elevation myocardial infarction (STEMI) presenting to non-percutaneous coronary intervention (PCI)-capable hospitals, rapid transfer to a PCI- capable center improves outcomes [1-3]. The 2013 American College of Cardiology Foundation/American Heart Association (ACC/AHA) guidelines for the management of STEMI recommend immediate Transfer of patients to a PCI-capable hospital, with a first medical contact-to-device time system goal of 120 minutes or less [4]. The development and utilization of regional

? Funding sources: This work was supported by Korean Center for Disease & Control.

* Corresponding author at: Laboratory of Emergency Medical Service, Seoul National University Hospital Biomedical Research Institute, 28-2, Yeongeon-dong, Jongno-gu, Seoul 110-799, Korea. Tel.: +82 10 9152 5955; fax: +82 2 744 3967.

E-mail addresses: [email protected] (J.H. Park), [email protected] (K.O. Ahn), [email protected] (S.D. Shin), [email protected] (W.C. Cha), [email protected] (H.W. Ryoo), [email protected] (Y.S. Ro), [email protected] (T. Kim).

networks for STEMI in the US and Europe have resulted in a reduction in the delays of Interhospital transfers [5]. On the other hand, in many other re- gions, interhospital transfer is still one of the major factors that delays the door-to-balloon time, especially in areas with underdeveloped or develop- ing stages of regionalization [6-8].

Goal of this study

The objective of this study was to understand the factors affecting the transfer process and total door-to-balloon time delay in STEMI patients undergoing interhospital transfer for primary PCI.

Materials and methods

Study design and setting

This study was a secondary analysis of the registry data of the Cardiovascular Disease Surveillance (CAVAS) program conducted by 23 tertiary academic emergency departments, sponsored by the Korean

http://dx.doi.org/10.1016/j.ajem.2015.12.058

0735-6757/(C) 2015

Centers for Disease Control and Prevention, during a period of approxi- mately 5 years (from November 1, 2007, to December 31, 2012). More detailed information about the CAVAS program has been described in previously published articles [9,10]. The study protocol was approved by the institutional review board of Seoul National university hospitals. The need for informed consent was waived by the board (institutional review board no. 1012-134-346).

Selection of participants

The CAVAS registry includes patients with acute myocardial infarc- tion (AMI) who presented for management at the participating hospi- tals’ emergency departments. All consecutive patients with a diagnosis of AMI based on the International Classification of Disease, 10th Revision discharge diagnosis (I21.0-I21.1, I21.2, I21.3, I21.4, and I21.9) were con- sidered eligible and screened for inclusion into the study. ST-elevation myocardial infarction was defined as associated ST-segment elevation in 2 or more leads or Left bundle-branch block upon electrocardiography at the receiving hospital. Among these patients, we limited our analysis to a final study population of patients with a STEMI symptom onset of less than 12 hours after presentation. Our analysis included patients who transferred from other hospitals and who underwent primary PCI in the participating hospitals. Patients who received any Fibrinolytic therapy at the referring hospital or who did not undergo primary PCI in the receiving hospital were excluded.

Data collection

The patient records included data on demographics, route of visit, emergency medical service (EMS) use, clinical characteristics, and therapies administered for STEMI. Based on the time of arrival at the referring hospital, we categorized the time of visit into office time (weekday arrival between 8 AM and 6 PM) and non-office time (week- day arrival between 6 PM and 8 AM or weekend arrival). The annual PCI volume was assessed by the receiving hospital’s capacity for rapid PCI; these were categorized as high and low volumes according to the annu- al case number (more and less than 200 cases, respectively) [11]. We categorized the urbanization levels as metropolitan, urban, and rural ac- cording to the population sizes, and the patients were classified based on their address/zip code. A total of 248 counties are contained within the boundaries of Korea, defined by the statute for geographical admin- istrative purposes (metropolitan, 95; urban, 67; rural, 86 counties in 2010) [12]. The metropolitan counties are segmented administrative areas of metropolitan cities (eg, Seoul) with populations of more than 500000, whereas the urban and rural counties are classified as those lo- cated in areas with populations of more and less than 100000 inhabi- tants, respectively.

Outcome measures

Our primary end point was the first door-to-balloon (D1toB) time, measured from the time of arrival at the referring hospital to the time of the first balloon inflation at the receiving hospital. The patients were divided into 2 groups according to the D1toB (D1toB b 120 vs >= 120 minutes).

The “process of care” was categorized according to the following time intervals: length of stay at the referring hospital (D1LOS), transport time from the referring to the receiving hospital (D1toD2), and the time interval from arrival to balloon inflation during primary PCI at the receiving hospital (D2toB).

Statistical analysis

Descriptive statistics were calculated and are reported as counts and percentages or medians and interquartile ranges (IQRs), as appropriate. Differences in the patient demographics, visit characteristics, and

clinical characteristics were compared between the D1toB b 120 and D1toB >= 120 groups using the ?² test. In order to identify the significant characteristics affecting the D1toB, a multivariable logistic regression model was constructed. The adjusted odds ratios (AORs) and 95% confi- dence intervals (CIs) were calculated after adjusting for potential risk factors, including age, sex, presenting symptom, time of visit, and the annual total PCI volume of the receiving hospital. For all analyses, a 2- sided P value less than .05 was considered statistically significant. Data management and analyses were performed using R software, version

3.02 (available at http://www.r-project.org).

Results

Demographic findings and comparison of D1toB

A total of 9989 STEMI patients were eligible for this study, of whom 1837 patients met all inclusion criteria and were included in the final analysis. Percutaneous coronary intervention was recommended for STEMI patients (n = 6418) with a symptom onset of less than 12 hours. Interhospital transport occurred in 2614 patients (40.7%). Among them, the following patients were excluded: (1) those who underwent revascularization, including thrombolysis, PCI, and Coronary artery bypass grafting before interhospital transfer (n = 150; 1.5%);

(2) those who did not undergo primary PCI at the receiving hospital (n = 503; 5.0%); and (3) those with a D1toB of more than 24 hours (n = 124; 1.2%) (Fig. 1).

Of the 1837 enrolled patients, 1299 (70.7%) patients were included in the D1toB >= 120 group, whereas 538 (29.3%) patients comprised the D1toB b 120 group. Compared with the D1toB b 120 group, the D1toB

>= 120 group comprised a higher proportion of women and patients living in rural areas (Table 1). In rural areas, only 16.0% of patients were included in the D1toB b 120 group, whereas the corresponding proportions in the urban and metropolitan areas were 28.3% and 41.4%, respectively (P b .01). Patients in the D1toB >= 120 group were less likely to have chest pain on presentation. Notably, patients who ex- perienced prehospital cardiac arrest or cardiogenic shock tended to have similar D1toB to patients who did not (Table 1). The time intervals of the “process of care” according to the D1toB groups are demonstrated in Fig. 2.

Multivariable analysis for D1toB

The urbanization level of the patients’ area of residence, presence of chest pain on presentation, and transfer to high-volume PCI hospitals were found to be significant independent factors associated with D1toB delays in the multivariable logistic regression analysis (Table 2). Especially even after adjusting for potential confounders, rural areas were significantly associated with D1toB delays (AOR, 2.01 [95% CI, 1.40-2.19] vs urban areas; AOR, 3.70 [95% CI, 2.59-5.38] vs metropol- itan areas).

Process of transfer

The median D1LOS and interhospital transport time were 50 (IQR, 30-100) minutes and 32 (IQR, 20-51) minutes, respectively. The median time interval from the door of the receiving hospital to balloon insertion was 55 (IQR, 40-79) minutes. The median D1toB time was 160 (IQR, 115-240) minutes. The mean proportion of D1LOS out of the total D1toB was 36.0%.

Fig. 3 shows the proportions of D1toB and the other 4 time intervals of the “process of care,” namely, symptom-to-first door time (S2D1), D1LOS, D1toD2, and D2toB according to the urbanization level. The S2D1 and D2toB did not differ according to the urbanization level (P = .9 and P = .08, respectively). However, the D1LOS and D1toD2 time intervals in the rural areas were longer than those of the urban and metropolitan areas (P = .02 and P b .01, respectively).

1,837

Patients analyzed

150 excluded

- Revascularization before transfer

503 excluded

- No PPCI at receiving hospital

124 excluded

- Total door to balloon time > 24h

Fig. 1. Patient flow in the present study. PPCI, primary percutaneous coronary intervention.

2,614

Patients experienced inter-hospital transport

3,804 excluded

- No inter-hospital transferred

6,418

Patients recommended PPCI

3,571 excluded

- Symptom onset to door time > 12h

9,989

STEMI patients enrolled

Discussion

Our nationwide multicenter study found that STEMI patients under- going interhospital transfer were at high risk of not receiving definite care within the recommended time window and that the process of transfer was the main factor responsible for this delay.

The primary outcome of our analysis was a D1toB time less than 120 minutes, rather than first Medical contact-to-balloon time. The reason for choosing this outcome measure is the unique EMS setting in South

Korea. The EMS is a public transportation system operated by a single call number, 1-1-9. During the study period, because no prehospital protocol for AMI patients had been established, the EMS transported presumed AMI patients to the nearest local emergency centers, without consideration for their capacity for AMI management. Only 16% of pa- tients this study used EMS in our study (Table 1). Although we did not find a significant association between EMS use and D1toB delays, this observation is limited because of the small number of patients who accessed EMS and our inability to estimate the hypothetical effect of

Table 1

Patient characteristics by total door-to-balloon time

Characteristica	Total door-to-balloon time		Pb
	N 120 min (n = 1299)	<= 120 min (n = 538)
Age (y), mean (SD)	63.3 (13.6)	61.1 (13.3)	b.01
Age N 65 y (n = 825)	614 (47.3%)	211 (39.2%)	b.01
Female sex (n = 502)	377 (29.0%)	125 (23.2%)	.01
Medical aid (n = 95)	71 (5.5%)	24 (4.5%)	.42
Urbanization level of residency			b.01
Rural (n = 306)	257 (29.1%)	49 (13.1%)
Urban (n = 513)	368 (41.7%)	145 (38.7%)
Metropolitan (n = 439)	258 (29.2%)	181 (48.3%)
Prior myocardial infarction (n = 69)	47 (3.6%)	22 (4.1%)	.69
Prior stroke (n = 87)	69 (5.4%)	18 (3.4%)	.09
Prehospital cardiac arrest (n = 24)	17 (1.3%)	7 (1.3%)	1
Chest pain at presentation (n = 1708)	1192 (91.8%)	516 (95.9%)	0
STEMI ECG in referring hospital (n = 1562)	1097 (91.5%)	465 (93.8%)	.14
Cardiogenic shock (n = 132)	98 (7.6%)	34 (6.3%)	.37
Mode of visit at referring hospital			.83
EMS use (n = 280)	199 (15.7%)	81 (15.2%)
Other (n = 1520)	1069 (84.3%)	451 (84.7%)
Office hour presentationc (n = 838)	574 (44.2%)	264 (49.1%)	.06
Transfer to PCI N 200 hospitals (n = 1088)	762 (58.7%)	326 (60.6%)	.47

Abbreviation: ECG, electrocardiogram.

^a Missing values: age (n = 1), prior myocardial infarction (n = 3), medical aid (n = 2), urbanization level of residency (n = 579), prior myocardial infarction (n = 12), prior stroke (n = 23), chest pain at presentation (n = 1), STEMI ECG in referring hospital (n = 142), cardiogenic shock (n = 2), and EMS use (n = 37).

^b P values were calculated by Student t test or Fisher exact test, as appropriate.

^c Office hour is defined as 8 AM to 6 PM on weekdays.

Fig. 2. The 4 individual Processes of care for STEMI compared according to D1toB time b120 vs >=120 minutes.

EMS in terms of direct transport to the PCI center on the time to balloon (Table 1). Most studies have demonstrated positive effects of EMS use on the time to balloon. However, in incomplete regionalization of the system of care for STEMI, such as in this study, the effect of EMS use might be attenuated by the interhospital transfer.

One of the most important findings of our nationwide multicenter study was that less than one-third the enrolled STEMI patients undergo- ing interhospital transfer for PCI (16.0% of cases from rural areas) showed a D1toB delay less than 120 minutes. In the early 2000s, the Na- tional Registry of Myocardial Infarction in the United States reported that 15.8% of cases of D1toB b 120 minutes occurred due to underdevel- oped regionalization for STEMI care [6]. After this study, regionalization of STEMI care was initiated in the United States, and, in 2007, the Mission: lifelines program was launched by the AHA. Recently, it was reported that this program has resulted in a first door-to-device time less than 120 minutes in 65% of patients with an expected transport time of less than 60 minutes [13]. In our study, among patients with a transport time of 60 minutes or less (n = 1481), the proportion of D1toB less than 120 minutes was 33.7%. The Ministry of Health & Welfare in Korea has created programs for developing regional centers for cardiovascular disease (RCV centers) and has successfully established 8 RCV centers between 2008 and 2012 in noncapital areas [14]. However, regionalization for STEMI patients is still in the develop- ing stage in Korea.

Our study demonstrated an association between low urbanization levels and lower frequency of D1toB b 120 minutes. This association remained after adjustment for several confounders. Recently, Dauerman et al [13] reported that Rural patients comprised 46% of all pa- tients with a first door-to-device time at least 120 minutes, as compared with 34% of patients with a first door-to-device time less than 120 mi- nutes. Moreover, similarly to this previous study, transport to a high- volume PCI center was found to be an independent predictor of achieve- ment for D1toB b 120 minutes in the present study [13].

In contrast to previous studies [6,13], our results showed that cardiac arrest and cardiogenic shock were not predictors of delay; the D1LOS of patients with cardiac arrest or cardiogenic shock (n = 149) did not differ compared with that of patients without (n = 1686; median [IQR], 46 [30-80] vs 53 [30-100] minutes; P = .09). The CAVAS registry

Table 2

Multivariable odds ratios (ORs) and 95% CIs for in-time length of total door-to-balloon

time

does not include information regarding the process of resuscitation efforts in the referring hospitals. However, there was no significant difference in the D1toD2 of patients with vs without cardiac arrest or cardiogenic shock (median [IQR], 32 [20-48] vs 32 [20-52] minutes; P = .9). Moreover, the proportion of transfers to high-volume PCI cen- ters was lower in patients with cardiac arrest or cardiogenic shock than in patients without (45.0% vs 60.4%; P b .01). One possible explana- tion for these findings may be that no delay due to resuscitation efforts was observed or that the transferring hospitals may choose closer, but smaller, receiving hospitals.

Our study revealed a median D1LOS of 50 (IQR, 30-100) minutes. This is longer than the 30 minutes recommended by the American College of Car- diology Foundation/AHA 2008 performance measures for STEMI and non- STEMI [15]. Recently, several studies focusing on the D1LOS in transferred STEMI patients have been published [16,17]. These studies reported median D1LOS times ranging from 51 (IQR, 35-82) minutes to 68 (IQR, 43-120) minutes. Miedema et al [7] focused on the reasons for these delays and determined that they occurred most frequently at the referring hospital (64.0%; n = 1298). Diagnostic dilemmas and nondiagnostic initial electro- cardiograms led to delays of the greatest magnitude. Similarly, our results showed that the absence of chest pain and ambiguous electrocardiograms in the referring hospitals were associated with delayed D1toB.

Similar to in previous studies, the D1toD2 markedly differed accord- ing to the urbanization level in the present report. Successful regional networks for STEMI have been reported in the rural areas of Illinois

[18] and Minneapolis [19], and the Minneapolis Heart Institution Hospi- tal Network for STEMI reported a median D1toB range of approximately 90 to 100 minutes, despite a median D1toD2 of 70 minutes [19]. In areas where regional network systems for STEMI have been successfully im- plemented, the transportation distance is not a barrier in achieving D1toB b 120 minutes, and the patient outcomes do not differ according to the transportation distance [20]. One possible method for reducing long D1toD2 times in rural areas is the utilization of air transport using helicopters. However, transportation using helicopters for inter- hospital transfers of STEMI patients is rare in Korea.

Finally, the median D2toB in our study was 55 (IQR, 40-79) minutes. These results were considered excellent. These relatively short D2toB times were thought to result from quality control programs for RCV cen- ters and the Health Insurance Review and Assessment Service [21,22].

Our study had several limitations. First, all included hospitals were ac- ademic teaching hospitals. The CAVAS program was an observational study that involved hospitals that volunteered to participate in the pro-

gram, and these tended to be larger and more specialized than the non-

Variables	OR (95% CI)	P
Age N 65 y	1.02 (0.77-1.34)	.89
Female	0.74 (0.54-1.01)	.06
Residency
Rural	Reference
Urban	2.01 (1.40-2.91)	b.01
Metropolitan	3.70 (2.59-5.38)	b.01
Chest pain at presentation	2.06 (1.18-3.83)	.02
Non-office hour presentation	0.82 (0.63-1.05)	.11
Transfer to high-volume PCI centers	1.35 (1.04-1.74)	.02

participating hospitals. The 75th percentile of D2toB in our study was less than 90 minutes. Second, our analysis did not include the patients’ outcomes, such as mortality. Hence, we could not adjust the outcomes

according to the STEMI severity, including the Killip classification, as this was not recorded in the CAVAS registry. Finally, information on the referring hospitals was not collected, except for the D1LOS. Data from the referring hospitals, such as the location, teaching or nonteaching status, processes involved in the transfer decisions, and capacity for STEMI management, are factors that can potentially influence the D1LOS.

Fig. 3. The 4 individual processes of care for STEMI compared according to the urbanization levels (metropolitan, urban, and rural).

Conclusion

The transfer of STEMI patients for primary PCI is frequently associat- ed with D1toB times of 120 minutes or more in Korea, with longer de- lays observed in rural areas. Weak regionalization has been identified as an important cause of these delays, and improvement of the process of care systems is urgently needed to reduce the time to reperfusion therapy in transfer patients.

Disclosures

None.

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