PHWR Public Health Weekly Report

The Republic of Korea aging population faces a rising tide of sudden cardiac arrest (SCA) linked to cardiovascular and cerebrovascular diseases [1]. SCA describes a constellation of conditions where the heart abruptly stops beating. This cuts off oxygen to vital organs like the brain, leading to tissue and brain damage, posing both health and socioeconomic challenges.

While recent reports show a steady rise in out-of-hospital cardiac arrests, survival and neurological recovery rates had been improving annually until 2018 [2]. This decline coincides with the coronavirus disease 2019 (COVID-19) pandemic, a trend mirrored in other countries [3]. Shin et al. [4] studies suggest factors like patient demographics such as sex and age, cause of cardic arrest, and every stage of medical care impact survival, highlight the importance of witnessing the arrest, pre-hospital care, cardiopulmonary resuscitation (CPR) at the emergency room (ER), and subsequent treatment. Ryu et al. [5] further argue that regional disparities in medical resources, population demographics, and transportation networks can influence outcomes. Notably, data from the Korea Disease Control and Prevention Agency (KDCA) reveals higher cardiac arrest incidence in Busan and Gyeongnam compared to the national average between 2016 and 2021 [2].

Therefore, this study aimed to identify the incidence patterns and characteristics of SCAs in the Gyeongnam region (Busan, Ulsan, and Gyeongnam), which has a high incidence of SCA. The findings of this study will provide evidence to seek ways to prevent and manage cardiac arrests in the future.

1. Subjects and Data Collection

This study utilized raw data from the National Survey on Sudden Cardiac Arrest (National Statistics Approval No. 117088) conducted by the KDCA in accordance with Article 6 of the Act on the Prevention and Management of Cardio-Cerebrovascular Diseases. This study included all patients with SCA transported by emergency service (EMS) ambulances in 2021. Subjects were identified by searching medical records for mentions of cardiac arrest, respiratory arrest, CPR administration, or automatic external defibrillator (AED) use. Patients with non-cardiac arrest after medical record review were excluded from this study. Thus, a total of 33,235 patients with SCA transported by EMS ambulance, of which 33,041 patients who completed medical record were enrolled in this study. Among the 33,041 patients, 2,365 patients (in Busan), 695 (in Ulsan), and 2,431 (in Gyeongnam) were included and analyzed from the Gyeongnam region.

2. Selection of Variables

Following a study by Kim and Chun [6], variables were categorized into individual level, pre-hospital phase, and hospital phase. Individual variables encompassed personal and sociodemographic characteristics before SCA, that used to sex and age in study. Pre-hospital stage variables encompassed determinants of survival outcomes from witnessed by someone after SCA to hospital arrival, such as arrest place, cause, witness status, bystander CPR, and return of spontaneous circulation (ROSC). Hospital stage variables encompassed determinants of survival outcomes from ER arrival without ROSC to discharge, such as ER CPR and AED use. Neurological outcome was assessed using the Cerebral performance category (CPC) scale at discharge, with scores of 1 or 2 indicating good neurological outcomes with independent daily living.

3. Analysis

Data collected in this study were analyzed and presented frequencies and percentages (%) using descriptive statistics. The statistical analysis was performed using the SPSS software program version 22.0 (IBM Co.).

1. Trends in the Incidence of SCA in the Gyeongnam Region

Analysis of the recent 6 years (2016–2021) revealed that the number of SCAs transported by 119 ambulances is steadily increasing (Figure 1A). By 2021, the national incidence rate reached 64.7 per 100,000 people. Jeju topped the regional rankings with 101.8, followed by Gangwon with 95.8, and Jeonnam with 90.0. Within the Gyeongnam region, Busan (72.4, 9th), and Gyongnam (73.5, 8th) were higher than the overall, while Ulsan was slightly lower on 60.1 (11th). This results showed that the percentage points (p%) of Busan (7.7), Gyeongnam (8.8) were higher level, respectively, compared to the overall excluding the Ulsan (Figure 1B).

Figure 1. The Trends in the Gyeongnam regional out-of-hospital cardiac arrest incidence per 100,000 persons
(A) Annual incidence. (B) Regional difference of patients in 2021.

Furthermore, analysis of the trends in survival-related characteristics over the recent 6 years showed that the rates of survival and neurological recovery deteriorated every year. Notably, the Gyeongnam region consistently was lower than the overall in 2021 (Figure 2A, B).

Figure 2. Survival related characteristic for 6 years (2016 to 2021 years)
(A) Survival rate: discharge alive. (B) Neurological recovery rate: brain function recovered enough to enable daily life. (C) Bystander cardiopulmonary resuscitation rate. (D) Return of spontaneous circulation rate before hospital arrival.

The bystander CPR rate was on the rise nationwide, it was remains concerningly low in Busan, Ulsan, and Gyeongnam compared to the overall (Figure 2C). Similarly, the ROSC rate before hospital arrival increased from 2016 (6.9%) to 2019 (8.2%), but decreased from 2020. In particular, the Gyeongnam region has shonw an earlier decline since 2018 (Figure 2D).

2. General Characteristics of Patients with Out-of-Hospital SCA in 2021

Of the 33,041 patients with out-of-hospital SCA in 2021, revealed regional variations within the Gyeongnam region (Busan, Ulsan, and Gyeongnam) (Table 1). The results showed that the Busan showed 2,365 patients (7.2%), Ulsan 695 (2.1%), and Gyeongnam 2,431 (7.4%). Similar to national trends, the incidence was higher in men and increased with age.

Table 1 Gyeongnam regional demographic and characteristics of out-of-hospital cardiac arrest^a) patients in 2021

Variable		Overall (n=33,041)	Busan (n=2,365)	Ulsan (n=695)	Gyeongnam (n=2,431)
Sex	Male	20,970 (63.5)	1,530 (64.7)	451 (64.9)	1,584 (65.2)
	Female	12,071 (36.5)	835 (35.3)	244 (35.1)	847 (34.8)
Age (yr)	<20	649 (2.0)	27 (1.1)	15 (2.2)	46 (1.9)
	20–29	908 (2.7)	62 (2.6)	21 (3.0)	57 (2.3)
	30–39	1,196 (3.6)	98 (4.1)	27 (3.9)	104 (4.3)
	40–49	2,391 (7.2)	149 (6.3)	53 (7.6)	171 (7.0)
	50–59	4,387 (13.3)	273 (11.5)	98 (14.1)	358 (14.7)
	60–69	5,924 (17.9)	462 (19.5)	141 (20.3)	446 (18.3)
	70–79	7,268 (22.0)	568 (24.0)	148 (21.3)	539 (22.2)
	≥80	10,318 (31.2)	726 (30.7)	192 (27.6)	710 (29.2)
Arrest place	Public	5,205 (15.8)	345 (14.6)	100 (14.4)	416 (17.1)
	Non-public	20,628 (62.4)	1,341 (56.7)	390 (56.1)	1,277 (52.5)
Causeb)	Cardiac origin	24,078 (72.9)	1,847 (78.1)	474 (68.2)	1,756 (72.2)
Witnessc)	Witnessed	17,140 (51.9)	1,131 (47.8)	322 (46.3)	1,173 (48.3)
Bystander CPRd)	CPR	8,381 (25.4)	431 (18.2)	126 (18.1)	469 (19.3)
Prehospital: ROSCe)	Recovered	2,406 (7.3)	160 (6.8)	39 (5.6)	160 (6.6)
Hospital: CPR	CPR	19,478 (59.0)	1,351 (57.1)	410 (59.0)	1,333 (54.8)
Defibrillation (ER)	Defibrillation	4,077 (12.3)	336 (14.2)	111 (16.0)	269 (11.1)
Past history	Hypertension	11,018 (33.3)	766 (32.4)	191 (27.5)	670 (27.6)
	Deabetes mellitus	7,410 (22.4)	519 (21.9)	130 (18.7)	462 (19.0)
	Heart disease	5,273 (16.0)	388 (16.4)	96 (13.8)	360 (14.8)
	Stroke	2,716 (8.2)	191 (8.1)	34 (4.9)	189 (7.8)
	Renal disease	1,925 (5.8)	140 (5.9)	33 (4.7)	92 (3.8)
	Pulmonary disease	2,150 (6.5)	153 (6.5)	48 (6.9)	151 (6.2)

Values are presented as number (%). CPR=cardiopulmonary resuscitation; ROSC=return of spontaneous circulation; ER=emergency room. ^a)A condition in which the heart suddenly decreases or stops beating. ^b)Mechanism of diseases or injuries that can directly induce sudden cardiac arrest. ^c)When someone witness a patient collapsing after sudden cardiac arrest. ^d)CPR performed by a bystander, not paramedics or medical staff before hospital arrival. ^e)Recovery to a state where blood circulation becomes possible without external help..

Non-public places were the most common location for SCAs, with caused by cardiogenic cardiac arrest similar to overall (24,078 patients, 72.9%). The proportion of witnessed SCAs was slightly lower than the overall, and bystander CPR was also lower than the overall. The rate of ROSC before hospital arrival showed 160 (6.8%) in Busan, 39 (5.6%) in Ulsan, and 160 (6.6%) in Gyeongnam, compared to 2,406 (7.3%) nationwide.

Hypertension, diabetes mellitus, and heart disease topped the list of past histories for Gyeongnam region with SCA patients, corresponded with national data.

3. Factors associated with Good Neurological Outcomes in the Gyeongnam Region

Nationwide, only 4.0% (1,326 out of 33,041) of SCA patients with good neurological outcomes at discharge. The proportion of Gyeongnam region was 6.0% in Busan (79 patients), 1.6% in Ulsan (21 patients), and 7.7% in Gyeongnam (102 patients) (Table 2).

Table 2 Characteristics of out-of-hospital cardiac arrest patients related to good neurological outcomes in 2021

Variable		Overall (n=1,326)	Busan (n=79)	Ulsan (n=21)	Gyeongnam (n=102)
Individual-level
Sex	Male	1,076 (81.1)	60 (75.9)	15 (71.4)	83 (81.4)
	Female	250 (18.9)	19 (24.1)	6 (28.6)	19 (18.6)
Age (yr)	<20	23 (1.7)	0 (0.0)	1 (4.8)	5 (4.9)
	20–29	49 (3.7)	3 (3.8)	0 (0.0)	4 (3.9)
	30–39	72 (5.4)	4 (5.1)	1 (4.8)	7 (6.9)
	40–49	223 (16.8)	8 (10.1)	0 (0.0)	18 (17.6)
	50–59	400 (30.2)	30 (38.0)	7 (33.3)	36 (35.3)
	60–69	345 (26.0)	21 (26.6)	10 (47.6)	20 (19.6)
	70–79	162 (12.2)	10 (12.7)	1 (4.8)	11 (10.8)
	≥80	43 (3.2)	3 (3.8)	1 (4.8)	1 (1.0)
Pre-hospital phase
Arrest place	Public	420 (31.7)	22 (27.8)	5 (23.8)	31 (30.4)
	Non-public	582 (43.9)	32 (40.5)	10 (47.6)	39 (38.2)
Cause	Cardiac origin	1,238 (93.4)	73 (92.4)	19 (90.5)	93 (91.2)
Witness	Witnessed	1,122 (84.6)	67 (84.8)	17 (81.0)	82 (80.4)
Bystander CPR	CPR	627 (47.3)	41 (51.9)	5 (23.8)	48 (47.1)
ROSC	Recovered	1,099 (82.9)	71 (89.9)	16 (76.2)	84 (82.4)
Hospital phase
CPR	CPR	227 (17.1)	8 (10.1)	5 (23.8)	18 (17.6)
Defibrillation	Defibrillation	151 (11.4)	6 (7.6)	2 (9.5)	12 (11.8)

Values are presented as number (%). CPR=cardiopulmonary resuscitation; ROSC=return of spontaneous circulation..

Several factors were associated with good neurological outcomes. Men was better than women, and aged in their 50 and 60 generally were better. Additionally, non-public places, caused by cardiogenic cardiac arrest, witness, and with bystander CPR, ROS were assoicated with good neurological outcomes. However, bystander CPR in 23.8% (a gap of 23.5%p), ROS in 76.2% (a gap of 6.7%p) were lower than the overall in Ulsan.

4. Regional Variations in Emergency Care in the Out-of-Hospital Phase

The bystander CPR rate steadily increased nationwide over the recent three years (24.7% in 2019 to 28.8% in 2021), and there was a significant regional disparities (Table 3). Busan and Ulsan were also increased similar to national trend, but Gyeongnam showed an initial increase until 2020, followed by a concerning decline in 2021.

Table 3 Regional difference of Initial response and pre-hospital ROSC

Variable		2019	2020	2021
Bystander CPR rate	Overall	24.7	26.4	28.8
	Max	38.4	40.7	44.4
	Min	12.2	12.8	10.4
	Max-Min	26.2	27.9	34.0
	Max/Min	3.1	3.2	4.3
	Busan	18.7	19.7	20.8
	Ulsan	14.8	16.8	20.0
	Gyeongnam	15.9	23.7	21.1
Pre-hospital ROSC rate	Overall	8.2	7.6	7.3
	Max	13.5	11.6	10.2
	Min	5.4	5.4	5.4
	Max-Min	8.1	6.2	4.8
	Max/Min	2.5	2.1	1.9
	Busan	10.6	9.1	7.2
	Ulsan	5.5	5.5	5.8
	Gyeongnam	5.6	7.0	6.0

Values are presented as percentage (%). CPR=cardiopulmonary resuscitation; ROSC=return of spontaneous circulation; Max=maximum; Min=minimum..

Nationally, Seoul topped the charts with a 44.4% bystander CPR rate in 2021, the bottom-ranked Jeonnam at 10.4%. Within the Gyeongnam region, Busan in 9th (20.8%), Ulsan in 12th (20.0%), and Gyeongnam in 8th (21.1%) occupied middle to lower ranks compared to the overall.

The trend in ROS rate was decreased from 8.2% in 2019 to 7.3% in nationwide, and regional disparities also persisted. The Daegu topped the charts with a 10.2% of ROS in 2021, while the button ranked Chungbuk with only 5.4%. Busan in 9th (7.2%), Ulsan in 15th (5.8%), and Gyeongnam in 14th (6.0%) occupied lower ranks compared to the overall.

This study aimed to investigate the current state and characteristics of patients with SCA in the Gyeongnam region during 2021, with the ultimate goal of informing strategies to improve future survival rates. Similar to the national trend, Gyeongnam region showed a concerning 6-year rise in out-of-hospital SCA incidence (2016–2021), unfortunately paired with a decline in survival and neurological recovery rates over the same period.

While bystander CPR rate was increased nationally, Gyeongnam region was below the overall. Consequently, the pre-hospital ROSC rate also presented a decreased trend in the area. These findings was consistent with prior research highlighting the crucial link between rates of bystander-CPR, ROSC before hospital arrival, and survival [6]. Furthermore, our results was related with a recent report indicating a significant decrease in survival and ROSC rates for Gyeongnam’s out-of-hospital cardiac arrest patients during the COVID-19 pandemic, compared to pre-pandemic times [3].

Through analysis of SCA patients in Gyeongnam region, it revealed that SCA survivors with good neurological outcome were most male, aged 50–60 years old, and suffered from cardiogenic cardiac arrest [7]. Studies suggest that sex disparity in SCA incidence could be due to genetic diversity, sex hormone influence, or sex-biased treatment [8] and age disparity could be resulted from the change of population related to aging. Also, SCA arrest place, specially non-public places like homes and nursing homes were related with good neurological outcome. This contradicts most previous studies suggesting public place with higher witness rates lead to better survival due to faster initial response. Therefore, further research is crucial to determine whether this is unique to Gyeongnam region or due to other factors.

This study emphasizes the critical need for repeated CPR and AED training, empowering family members to respond before the 119 EMS crew arrives. Mandatory workplace training, particularly for nursing home staff, is also recommended obligately, along with initiatives to raise awareness and promote early response skills in emergencies. Prior research found that witnessed SCA patients have a 2.6 times higher survival rate [8]. This aligns with our findings showing a high proportion of good neurological outcomes among witnessed incidents. This means that the witnessing leads to quicker calls for help and prompt bystander CPR, boosting both survival and positive outcomes.

Patients with good neurological outcomes often received bystander CPR, highlighting its crucial role in SCA survival. This finding aligns with Lee et al. [9], who insist that pre-hospital CPR is the critical intervention determining survival. Even though bystander CPR rate is rising every year, our country is still low at 28.8% in 2012 compared to 41.0% in the United States in 2012. Moreover, bystander CPR in Gyeongnam region is lower than the national level, and also shows the differences between each region. Numerous studies have been reported the positive impact of CPR educational programs. Developed countries like the US and Europe actively promote national-level CPR education and offer related policy support. While our country is developing national policies and standardized programs in CPR, bystander CPR implementation is still low compared to other countries like Denmark (45%) and Sweden (51%). Therefore, in the order to increase the bystander CPR, it is necessary that the efforts, such as expansion of CPR training targets, increase of training experience rates, and intensification of public awareness must be sustained.

A study by Reynolds et al. [10], found that over 90% of patients with good neurological outcomes regained spontaneous circulation within 20 minutes of CPR. Our study also showed the similar results which 82.9% of good-outcome patients (89.9% in Busan, 76.2% in Ulsan, and 82.4% in Gyeongnam) is achieved the ROSC. These findings reinforce the critical role of bystander CPR in improving the ROSC rates for out-of-hospital cardiac arrest patients. However, while bystander CPR implementation grew during the COVID-19 pandemic, the ROSC rate declined. The changes in individual healthcare as well as EMS including insufficient and infected 119 EMS crew could have negatively impacted these patient survival outcomes. In addition, due to regional disparities within these trends, further research to analyze characteristics within the region may be required.

In summary, our study suggests that the neurological outcomes for out-of-hospital SCA patients are influenced by sex, age, cause of cardiac arrest, arrest place, witnesses, bystander CPR, and ROSC, interconnectedly.

Though ER CPR and AED interventions in hospital were administered, their outcome rates were significantly lower compared to cases with pre-hospital ROSC. This suggests that these interventions were primarily implemented for patients in critical condition who have not regained spontaneous circulation upon arrival. Consequently, their overall success rate was understandably lower.

This study has limitations that the characteristics related to SCA were analyzed at the city-province level in Gyeongnam, not at the city, county, and district levels. However, it is important to analyze the data of Gyeongnam region in a large-scale national SCA survey, and finally hope that these findings can be used for prevention and management of SCA in the region.

Ethics Statement: Not applicable.

Funding Source: None.

Acknowledgments: None.

Conflict of Interest: The authors have no conflicts of interest to declare.

Author Contributions: Conceptualization: HIL, SJP. Data curation: HIL. Formal analysis: HIL. Project administration: SJP. Writing–original draft: HIL. Writing–review & editing: SJP.