Utilization of Intensive Care Units and Outcomes Based on Admission Wards in Cardiovascular Emergencies

Abstract

Background: Cardiovascular emergencies often require intensive care unit (ICU) management, but there is limited data comparing outcomes based on the admission ward.
Methods and Results: We analyzed data from the Japanese Registry of All Cardiac and Vascular Diseases Diagnosis Procedure Combination (JROAD-DPC) database (2016–2020) for 715,054 patients (mean age, 75.4±14.2 years, 58.4% male) admitted with acute myocardial infarction (N=175,974), unstable angina (N=45,308), acute heart failure (N=179,871), acute aortic dissection (N=58,597), pulmonary embolism (N=17,009), or post-cardiac arrest (N=184,701). Patients were categorized into 4 groups: intensive care add-ons 1/2, 3/4 (ICU 1/2, 3/4), high-care unit (HCU), and general wards. Comparisons included patient characteristics, hospitalization duration, mortality rates, and rates of defibrillation or cardiopulmonary resuscitation (CPR) defined by chest compression. General ward patients were the oldest and with shortest hospitalization durations. Additionally, mortality rates were the highest in general wards for acute heart failure, myocardial infarction, and aortic dissection. Defibrillation rates were 7.0%, 5.6%, 3.1%, and 4.3%, for ICU 1/2, 3/4, HCU, and general ward, respectively, with corresponding mortality rates of 40.4%, 44.1%, 44.6%, and 79.3%. CPR rates were 10.1%, 9.5%, 6.2%, and 3.1%, with mortality rates of 71.0%, 73.9%, 78.4%, and 97.7%, respectively.
Conclusions: High mortality rates in general wards highlight the importance of ICU management, particularly for acute myocardial infarction and aortic emergencies. These findings support prioritizing ICU admission for these critical conditions.

Full text

Circulation Journal
doi: 10.1253/circj.CJ-24-1043
million people globally are living with heart and circula-
tory diseases.5 Conditions such as acute myocardial infarc-
tion, unstable angina, acute heart failure, acute aortic
dissection, pulmonary embolism, and post-cardiac arrest
represent critical events that necessitate immediate and
Cardiovascular diseases (CVDs) are a leading cause
of morbidity and mortality worldwide, often
requiring urgent medical intervention due to the
potential for sudden deterioration.1–4 Approximately 20
million deaths reported in 2021 and approximately 640
Received January 6, 2025; accepted January 11, 2025; J-STAGE Advance Publication released online March 14, 2025 Time for
primary review: 5 days
Division of Public Health, Center for Community Medicine (M. Kuwabara), Division of Cardiovascular Medicine, Department of
Medicine (M. Kuwabara), Jichi Medical University, Tochigi; Division of Cardiovascular Intensive Care, Nippon Medical School
Hospital, Tokyo (T.Y.); Department of Cardiovascular Emergency (Y.T.), Department of Medical and Health Information
Management (Y.S., Y.M.), National Cerebral and Cardiovascular Center, Osaka; Emergency and Critical Care Center, Dokkyo
Medical University, Tochigi (M. Kikuchi); Department of Emergency and Critical Care Medicine, Shinshu University, Nagano (H.I.);
Advanced Critical Care Center, Medical Center, Yokohama City University, Yokohama (I.T.); Department of Cardiovascular
Medicine, Kawaguchi Cardiovascular and Respiratory Hospital, Saitama (N.S.); Division of Cardiology, Department of Internal
Medicine, Division of Community Medicine, Department of Medical Education, School of Medicine, Iwate Medical University,
Iwate (T. Itoh); Department of Cardiology, Saitama Medical University/Saitama Medical Center, Saitama (S.I.); Department of
Cardiovascular Medicine, Juntendo University Nerima Hospital, Tokyo (K.I.); Department of Cardiovascular Medicine, Faculty
of Medicine, University of Tsukuba, Ibaraki (T. Ishizu); Cardiovascular Medicine, Graduate School of Medicine, Toho University,
Tokyo (T. Ikeda); Department of Cardiovascular Medicine, Graduate School of Medicine, Gifu University, Gifu (H.O.); Department
of Cardiovascular Medicine, Graduate School of Medicine, Chiba University, Chiba (Y.K.); and Department of Cardiovascular
Medicine, Nippon Medical School, Tokyo (K.A.), Japan
(Footnote continued the next page.)
Utilization of Intensive Care Units and Outcomes Based on
Admission Wards in Cardiovascular Emergencies
Masanari Kuwabara, MD, PhD, FJCS; Takeshi Yamamoto, MD, PhD, FJCS;
Yoshio Tahara, MD, PhD, FJCS; Migaku Kikuchi, MD, PhD; Hiroshi Imamura, MD, PhD;
Ichiro Takeuchi, MD, PhD; Naoki Sato, MD, PhD; Tomonori Itoh, MD, PhD, FJCS;
Yoko Sumita, RN; Yoshihiro Miyamoto, MD, PhD; Shiro Ishihara, MD, PhD;
Kikuo Isoda, MD, PhD, FJCS; Tomoko Ishizu, MD, PhD, FJCS;
Takanori Ikeda, MD, PhD, FJCS; Hiroyuki Okura, MD, PhD, FJCS;
Yoshio Kobayashi, MD, PhD, FJCS; Kuniya Asai, MD, PhD, FJCS;
on behalf of Japanese Circulation Society Emergency and Critical Care Committee
Background: Cardiovascular emergencies often require intensive care unit (ICU) management, but there is limited data comparing
outcomes based on the admission ward.
Methods and Results: We analyzed data from the Japanese Registry of All Cardiac and Vascular Diseases Diagnosis Procedure
Combination (JROAD-DPC) database (2016–2020) for 715,054 patients (mean age, 75.4±14.2 years, 58.4% male) admitted with
acute myocardial infarction (N=175,974), unstable angina (N=45,308), acute heart failure (N=179,871), acute aortic dissection
(N=58,597), pulmonary embolism (N=17,009), or post-cardiac arrest (N=184,701). Patients were categorized into 4 groups: intensive
care add-ons 1/2, 3/4 (ICU 1/2, 3/4), high-care unit (HCU), and general wards. Comparisons included patient characteristics, hospi-
talization duration, mortality rates, and rates of defibrillation or cardiopulmonary resuscitation (CPR) defined by chest compression.
General ward patients were the oldest and with shortest hospitalization durations. Additionally, mortality rates were the highest in
general wards for acute heart failure, myocardial infarction, and aortic dissection. Defibrillation rates were 7.0%, 5.6%, 3.1%, and
4.3%, for ICU 1/2, 3/4, HCU, and general ward, respectively, with corresponding mortality rates of 40.4%, 44.1%, 44.6%, and 79.3%.
CPR rates were 10.1%, 9.5%, 6.2%, and 3.1%, with mortality rates of 71.0%, 73.9%, 78.4%, and 97.7%, respectively.
Conclusions: High mortality rates in general wards highlight the importance of ICU management, particularly for acute myocardial
infarction and aortic emergencies. These findings support prioritizing ICU admission for these critical conditions.
Key Words: Cardiac arrest; Cardiovascular diseases; Deaths; Intensive care units; Myocardial infarction
ORIGINAL ARTICLE
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2KUWABARA M et al.
sons were also made regarding the wards of hospitalization
according to Killip classication and the corresponding
mortality rates. Additionally, we analyzed the proportion
of patients who underwent debrillation or cardiopulmo-
nary resuscitation (CPR), as dened by chest compression
in this study, and their corresponding mortality rates across
the 4 ward groups. Moreover, we examined the frequency
and rate of debrillation or CPR on each hospitalization
during the rst 7 days of admission across the wards.
Patient Involvement
No patient involvement was required in the development
of the research question, outcome measures, study design,
or implementation. There are no plans to involve patients
in the dissemination of the study results.
Inclusion and Exclusion Criteria
We utilized the JROAD-DPC data to identify patients
with CVDs. We included patients who were transported to
the hospital via ambulance and excluded those who arrived
without ambulance transport or those with unknown
transport status.
Statistical Analysis
The level of statistical signicance was set at P<0.05 (two-
sided). Data are presented as mean ± standard deviation for
continuous variables and as percentages for categorical
variables. Comparisons between groups were conducted
using Student’s t-test for normally distributed continuous
variables and χ2 test for categorical variables.
When comparing age, hospitalization duration, and
mortality rates across wards, analysis of variance (ANOVA)
was used, followed by adjustments with Tukey’s post-hoc
test.
Statistical analyses were conducted using SPSS Statistics
software version 25 for Windows (IBM SPSS Statistics;
IBM, New York, USA).
Ethical Considerations
This study was conducted in accordance with the Declaration
of Helsinki. The JROAD-DPC database contains anony-
mized patient data with all personal identiers removed
through a standardized process.14 Each participating hospital
anonymized patients’ IDs using hospital-specic code change
equations before data submission.
The study protocol was approved by the Ethics Committee
of Nippon Medical School (approval number: B-2022-517).
The requirement for individual informed consent was
waived due to the retrospective and anonymized nature of
the data.15
Results
Ward Distribution of Admissions by Disease
We identied 1,306,635 patients with CVDs during the
study period. Of them, 715,054 patients with ambulance
intensive medical care.4,6 Traditionally, these acute cardio-
vascular events are managed in intensive care units (ICUs),
where specialized monitoring and treatment, including
rehabilitation, can be provided to improve patient out-
comes.7,8
Despite the critical nature of these conditions, there is a
notable gap in the literature regarding the incidence and
management of sudden cardiovascular deterioration that
occurs outside of ICUs, particularly in general wards.9
General wards are typically not equipped with the same
level of monitoring and rapid intervention capabilities as
ICUs, which may result in poorer outcomes for patients
experiencing acute cardiovascular events.10
The lack of comprehensive data on the frequency and
outcomes of such acute deterioration while in general
wards presents a signicant challenge for healthcare sys-
tems. Understanding these dynamics is crucial for develop-
ing strategies to improve the management of CVD across
dierent hospital settings. In this study we aimed to
address this gap by analyzing data from the Japanese
Registry of All Cardiac and Vascular Diseases Diagnosis
Procedure Combination (JROAD-DPC) from 2016 to
2020.11 By examining patient outcomes based on the level
of care received, this research sought to elucidate the
importance of ICU management for acute cardiovascular
events and provide evidence to guide improvements in
both healthcare policy and practice.
Methods
Study Design and Study Subjects
This was a retrospective analysis of the JROAD-DPC
database, a comprehensive nationwide registry maintained
by the Japanese Circulation Society (JCS). The database
includes data from all participating training hospitals al-
iated with the JCS. Diagnoses and comorbidities were
classied using the International Classication of Diseases,
10th Revision (ICD-10).
From the JROAD-DPC database we identied patients
admitted via ambulance transport with conditions such as
acute myocardial infarction, unstable angina, acute heart
failure, acute aortic dissection, pulmonary embolism, and
post-cardiac arrest between January 2016 and December
2020. Patients were categorized into 4 groups based on
their care setting: ICU with intensive care add-on 1/2 (ICU
1/2), ICU with intensive care add-on 3/4 (ICU 3/4), high-
care unit (HCU), and general wards.12 These categories
were based on the Japanese medical reimbursement sys-
tem, where “add-ons” refer to additional fees dened by
the DPC framework.13 The classication reected the level
of intensive care provided, with higher add-on codes cor-
responding to more resource-intensive care settings.
We compared patient demographics, including age, length
of hospital stay (hospitalization duration), and in-hospital
death (mortality rates), 1-day, 7-day, and 30-day in-hospital
mortality rate. For acute myocardial infarction, compari-
The rst two authors contributed equally to this work (M.K., T.Y.).
Mailing address: Masanari Kuwabara, MD, PhD, FJCS, Division of Public Health, Center for Community Medicine & Division
of Cardiovascular Medicine, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498,
Japan. email: kuwamasa728@gmail.com and Takeshi Yamamoto, MD, PhD, FJCS, Division of Cardiovascular Intensive
Care, Nippon Medical School Hospital, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan. email:
yamamoto56@nms.ac.jp
All rights are reserved to the Japanese Circulation Society. For permissions, please email: cj@j-circ.or.jp
ISSN-1346-9843
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3CVD and ICUs
HCU, 19.8±18.5 days; and general wards, 12.4±16.3 days;
P<0.001 for each pair, ANOVA with Tukey’s post-hoc
method). The mortality rate among all the study patients
was 34.2%. Patients in the higher-care units showed lower
mortality (ICU 1/2, 16.5%; ICU 3/4, 16.0%; HCU, 14.4%;
and general wards, 43.2%; P<0.05 for each pair, ANOVA
with Tukey’s post-hoc method) (Table 1). These ndings
indicated that patients in the general ward group were
older, had shorter hospital stays, and worse outcomes
compared with the other groups.
We compared in-hospital death (mortality rates), 1-day,
7-day, and 30-day in-hospital mortality rates across wards
for the following groups: acute heart failure, myocardial
infarction, and acute aortic dissection including type B
aortic dissection. The results revealed that, for all these
conditions, patients in the general ward had signicantly
worse outcomes across all metrics (ANOVA with Tukey’s
post-hoc method, P<0.05 for each pair) (Figure 3).
For acute myocardial infarction, comparisons regarding
the wards of hospitalization according to Killip classica-
tion and the corresponding mortality rates are shown in
Table 2. The rates of patients with acute myocardial infarc-
tion admitted to general wards and their respective out-
comes in Killip classes I, II, III, and IV were as follows:
43.9% of Killip I patients, with a mortality rate of 3.0%;
42.1% of Killip II patients, with a mortality rate of 6.1%;
42.3% of Killip III patients, with a mortality rate of 17.6%;
and 45.4% of Killip IV patients, with a mortality rate of
58.9%. These mortality rates in general wards were signi-
cantly higher than those in the higher-care units, especially
in Killip classes II, III, and IV (ANOVA with Tukey’s post-
hoc method, P<0.05 for each pair). These ndings indi-
transport were enrolled in this study after excluding
590,772 patients without ambulance transport and 859
patients with unknown transport. The main causes of
admission were acute heart failure (N=179,871), myocar-
dial infarction (N=175,974), unstable angina (N=45,308),
acute aortic dissection (N=58,597), including type B aortic
dissection (N=19,771), pulmonary embolism (N=17,009),
and post-cardiac arrest (N=184,701) (Figure 1).
The number of patients admitted to each of the 4 ward
types was: 42,249 patients to ICU 1/2, 111,220 patients to
ICU 3/4, 79,425 patients to HCU, and 482,160 patients to
general wards. The proportion of patients admitted to each
ward for each disease is shown in Figure 2. For acute myo-
cardial infarction and acute aortic dissection including
type B aortic dissection, >50% of patients were admitted
to intensive care (ICU 1/2, ICU 3/4, or HCU). In contrast,
approximately 30% of patients with acute heart failure,
unstable angina, or pulmonary embolism, and only
approximately 10% of those with post-cardiac arrest, were
admitted to these units.
Patients’ Characteristics and Mortality Rates Across the
Wards
The mean age of the 715,054 study patients was 75.4±14.2
years, and 58.2% were male. The higher-care units, includ-
ing ICU and HCU, admitted younger patients (ICU 1/2,
71.0±13.5 years; ICU 3/4, 71.8±13.4 years; HCU, 75.3±13.5
years; and general wards, 76.7±14.4 years, P<0.001 for
each pair, ANOVA with Tukey’s post-hoc method). The
mean hospitalization duration among all the study patients
was 18.0±18.0 days. Patients in the higher-care units stayed
longer (ICU 1/2, 23.3±21.3 days; ICU 3/4, 21.2±19.9 days;
Figure 1. Flowchart of the study. JROAD-DPC, Japanese Registry of All Cardiac and Vascular Diseases Diagnosis Procedure
Combination.
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4KUWABARA M et al.
The frequency and rate of debrillation or CPR on each
hospitalization day during the rst 7 days of admission
across the wards are shown in Figure 4. The frequency of
debrillation or CPR was highest on the day of admission;
however, these interventions remained frequent, particu-
larly during the rst 3 days of hospitalization. Even on the
7th day after admission, patients with CVDs were consid-
ered to still have a certain level of risk for sudden events
such as cardiac arrest.
Frequency of Debrillation or CPR in Acute Myocardial
Infarction
For acute myocardial infarction, the frequency of debril-
lation or CPR on each hospitalization day during the rst
7 days of admission across the wards and among patients
in Killip classes I–IV is shown in Figure 5. The frequency
of both debrillation and CPR was particularly high dur-
ing the rst 3 days and gradually decreased thereafter
across all groups. However, even on the 7th day, both inter-
ventions were still observed even in the general wards,
which is not low frequency. When analyzed by Killip clas-
cated that patients with acute myocardial infarction
admitted to general wards had signicantly worse out-
comes, particularly in higher Killip classes.
Frequency of Debrillation or CPR and Their Corresponding
Mortality Rates Across the Wards
The overall debrillation rate was 4.5%, with a corre-
sponding mortality rate of 66.3%. Among the ward groups,
debrillation was performed in 7.0% of patients in ICU
1/2, 5.6% in ICU 3/4, 3.1% in HCU, and 4.3% in general
wards. The corresponding mortality rates were 40.4%,
44.1%, 44.6%, and 79.3% (Table 3A). Similarly, the overall
frequency of CPR across all wards was 23.5%, with a cor-
responding mortality rate of 94.9%. When analyzed by
ward group, CPR was performed in 10.1% of patients in
ICU 1/2, 9.5% in ICU 3/4, 6.2% in HCU, and 30.8% in
general wards. The corresponding mortality rates were
71.0%, 73.9%, 78.4%, and 97.7% (Table 3B). These results
indicated that the general ward group had the highest
mortality rate after debrillation or CPR, reecting worse
outcomes compared with the higher-care units.
Table 1. Patients’ Characteristics by Ward Type and Prognosis
No. of
patients
Mean age
(years) Male Hospitalization
duration (days)
Mortality
rate
Intensive care unit (1/2) 42,249 71.0±13.5 64.6% 23.3±21.3 16.5%
Intensive care unit (3/4) 111,220 71.8±13.4 65.0% 21.2±19.9 16.0%
High-care unit 79,425 75.3±13.5 60.0% 19.8±18.5 14.4%
General wards 482,160 76.7±14.4 56.0% 12.4±16.3 43.2%
Total 715,054 75.4±14.2 58.4% 18.0±18.0 34.2%
Figure 2. Ward distribution of admissions by disease. HCU, high-care unit; ICU 1/2, intensive care unit with intensive care add-on
1/2; ICU 3/4, intensive care unit with intensive care add-on 3/4.
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5CVD and ICUs
Figure 3. Comparison of mortality rates across wards for acute heart failure, acute myocardial infarction, and acute aortic dissec-
tion. The dotted lines indicate significant differences through ANOVA with Tukey’s post-hoc method (P<0.05 for each pair). ANOVA,
analysis of variance; GW, general wards; HCU, high-care units; ICU 1/2, intensive care unit with intensive care add-on 1/2; ICU
3/4, intensive care unit with intensive care add-on 3/4.
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6KUWABARA M et al.
with severe cardiovascular conditions are promptly identi-
ed and transferred to higher-care units where they can
receive the necessary level of treatment. An observational
cohort study using a national administrative inpatient
database for acute-care hospitals in Japan from 2011 to
2018 reported that the incidence of in-hospital cardiac
arrest per 1,000 hospital admissions was 5.1.16 However, in
the present study, for cardiovascular emergencies the inci-
dence of CPR was 23.5%, substantially exceeding the pre-
vious report. This nding emphasizes the critical nature of
the initial hospitalization period and supports the prefer-
ence for higher-care unit management whenever possible.
These results provide compelling evidence for healthcare
policy reform, particularly regarding resource allocation
and the management of patients with cardiovascular emer-
gencies.
Higher-care units play a pivotal role in the management
of cardiovascular emergencies. This study showed that
patients in ICUs, especially those with ICU add-ons, tend
to be younger and have longer hospital stays, reecting a
more aggressive and comprehensive treatment approach.
The higher rates of debrillation or CPR observed in the
ICUs, coupled with lower mortality rates, suggest that
these units are better equipped to handle the complexities
of cardiovascular emergencies. The availability of special-
ized sta and advanced medical technology in ICUs allows
for more timely and eective interventions, which can sig-
nicantly improve patient survival and recovery.16
The ndings of this study have important implications
for healthcare policy and resource allocation in Japan.
sication, patients in higher Killip classes (III and IV) had
a higher frequency of debrillation or CPR compared with
those in lower classes (I and II), with Killip class IV patients
exhibiting the highest frequencies, particularly on the rst
3 days. These ndings highlight the concentration of criti-
cal interventions in higher-care units and among patients
in more severe Killip classes, particularly during the early
days of hospitalization.
Discussion
This study, utilizing the JROAD-DPC database, demon-
strated the outcomes for patients admitted via ambulance
transport with CVDs, including acute heart failure, myo-
cardial infarction, and acute aortic dissection. Patients
admitted to general wards with CVDs had signicantly
higher mortality rates than those in higher-care units. A
striking nding was that nearly half of patients with severe
acute myocardial infarction (Killip class IV) were managed
in general wards in Japan, despite signicant mortality dif-
ferences between general wards and higher-care units. Par-
ticularly concerning was the nding that mortality rates in
general wards were consistently higher across all Killip
classications, with a notably high 58.9% mortality rate for
Killip IV patients.
General wards lack sucient monitoring and rapid
response capabilities and this lack of specialized equipment
and personnel may delay the initiation of life-saving inter-
ventions, contributing to poorer patient outcomes. This
underscores the importance of ensuring that patients
Table 2. Admission Ward and Mortality Rate of Patients With Acute Myocardial Infarction by Killip Classification
Killip 1 Killip 2 Killip 3 Killip 4
N (rate) Mortality N (rate) Mortality N (rate) Mortality N (rate) Mortality
ICU 1/2 7,098 (9.3%) 2.6% 3,355 (8.8%) 4.7% 1,794 (13.1%) 12.3% 3,344 (11.9%) 37.5%
ICU 3/4 22,667 (29.6%) 2.2% 10,990 (28.9%) 4.7% 3,721 (27.2%) 15.1% 8,558 (30.4%) 36.8%
HCU 13,211 (17.3%) 2.0% 7,673 (20.2%) 4.5% 2,371 (17.4%) 15.1% 3,472 (12.3%) 34.6%
General wards 33,580 (43.9%) 3.0% 15,985 (42.1%) 6.1% 5,772 (42.3%) 17.6% 12,776 (45.4%) 58.9%
Total 76,556 2.5% 38,003 5.2% 13,658 15.8% 28,150 46.7%
HCU, high-care unit; ICU 1/2, intensive care unit with intensive care add-on 1/2; ICU 3/4, intensive care unit with intensive care add-on 3/4.
Table 3. Frequency of Defibrillation or CPR by Ward Type and Prognosis
(A) Defibrillation No. of
patients Defibrillation Rate Mortality rate with
defibrillation
Mortality rate without
defibrillation*
ICU 1/2 42,249 2,952 7.0% 40.4% 14.7%
ICU 3/4 111,220 6,178 5.6% 44.1% 14.4%
HCU 79,425 2,462 3.1% 44.6% 13.5%
General wards 482,160 20,566 4.3% 79.3% 41.6%
Total 715,054 32,158 4.5% 66.3% 32.7%
(B) CPR No. of
patients CPR Rate Mortality rate with
CPR
Mortality rate without
CPR*
ICU 1/2 42,249 4,247 10.1% 71.0% 10.4%
ICYU 3/4 111,220 10,525 9.5% 73.9% 10.0%
HCU 79,425 4,910 6.2% 78.4% 10.2%
General wards 482,160 148,667 30.8% 97.7% 18.9%
Total 715,054 168,349 23.5% 94.9% 15.5%
*Provided as a reference: these numbers represent the mortality rate of patients who did not undergo defibrillation or CPR. CPR cardiopulmo-
nary resuscitation. Other abbreviations as in Table 2.
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7CVD and ICUs
mortality rates, greater resource utilization, and lower dis-
charge rates to home compared with early in-hospital car-
diac arrest (hospital day zero).21 The study results21 suggested
that prompt intervention through early intensive care for
acute myocardial infarction may reduce in-hospital cardiac
arrest and improve outcomes. Cardiogenic shock compli-
cates 6–10% of ST-elevation myocardial infarction
(STEMI) cases, with hospital mortality rates approaching
50%.22 Although shock often develops early, it is typically
not diagnosed at the time of hospital presentation.22 In the
SHOCK trial, among patients with STEMI who eventually
developed shock during hospitalization, in approximately
50% it occurred within 6 h and in 75% within 24 h.23 There-
fore, the European Society of Cardiology (ESC) guidelines
recommend that patients with STEMI be managed in
coronary care units, which are comparable to ICUs in
Japan, for a minimum of 24 h, and monitoring in a special-
ized bed for 48–72 h after admission is recommended.24
However, the results of our study indicated that >40% of
all acute myocardial infarction cases were managed in general
wards. Notably, >45% of the patients with severe Killip
class IV conditions were treated in general wards. These
real-world data suggest that improvements in the manage-
ment of acute myocardial infarction are needed in Japan.
While this study provides valuable insights, several limi-
tations must be acknowledged. The retrospective nature of
the analysis and reliance on registry data may not capture
There is a clear need for strategic planning to ensure that
patients with cardiovascular emergencies are rapidly tri-
aged and admitted to appropriate care settings.17–19 This
may involve increasing ICU capacity, enhancing the capa-
bilities of general wards, or implementing systems to facil-
itate the swift transfer of patients to ICUs when necessary.
Additionally, training programs for general ward sta on
the early recognition and management of acute cardiovas-
cular events could help bridge the gap in care quality
between dierent hospital settings.20
Regarding the dierent mortality rates among the wards,
it is possible that higher mortality rates in general wards
might partially reect more end-of-life care practices. In
fact, the frequency of CPR on admission day was notably
higher in general wards. However, the continued occur-
rence of CPR in the days following admission is typically
not performed for end-of-life patients, which suggests
ongoing acute treatment rather than a purely palliative
situation. Moreover, the study’s analysis of patients with
acute myocardial infarction excluded those with post-car-
diac arrest who were predominantly (90%) managed in
general wards. This exclusion helped minimize the con-
founding eect of end-of-life care when comparing mortal-
ity rates.
A cohort study among patients with acute myocardial
infarction showed that delayed in-hospital cardiac arrest
(on or after hospital day 1) was associated with higher
Figure 4. Daily frequency of defibrillation or cardiopulmonary resuscitation (CPR) during the first 7 days of admission across
wards. The number of cases and the rate on the admission day (day 0) are separately indicated in text within the graph, as they
are numerous. AMI, acute myocardial infarction; HCU, high-care unit; ICU 1/2, intensive care unit with intensive care add-on 1/2;
ICU 3/4, intensive care unit with intensive care add-on 3/4.
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8KUWABARA M et al.
cular emergencies.
Acknowledgments
We express our sincere gratitude to the sta, members of the Japanese
Circulation Society Emergency and Critical Care Committee, and all
organizations and institutions involved in this study for their valuable
contributions and support. During the preparation of this manu-
script, the authors utilized ChatGPT and Perplexity AI in order to
proofread the English text and validate the manuscript’s content.
Sources of Funding
None.
Disclosures
Some authors of this article are members of Circulation Journal’s
Editorial Team: Y.K. serves as a Senior Advisory Editor, while T.
Ikeda, H.O., and Y.T. serve as Associate Editors.
IRB Information
This study received approval from the Ethics Committee of Nippon
Medical School (approval number: B-2022-517).
Data Availability
The JROAD-DPC data used in this study can be obtained by apply-
ing to the JROAD Oce of the JCS (Department of Information Use
Promotion, National Cerebral and Cardiovascular Center). Access to
the data is granted following review and approval. For more details,
please visit the ocial website: https://www.j-circ.or.jp/jittai_chosa/
about/summary/
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The ndings highlight the urgent need for healthcare
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