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Out-of-hospital and in-hospital cardiac arrest of non-cardiac origin: a retrospective two-period comparison at a Slovenia tertiary center

This retrospective study comparing non-cardiac-origin cardiac arrest patients in Slovenia between 2010/2011 and 2022/2023 found that while the proportion of out-of-hospital events and bystander CPR increased alongside more intensive management, overall survival and neurological outcomes remained unchanged despite improved survival rates specifically for in-hospital arrests.

Original authors: Ema Kocjancic, Anja Jazbec, Spela Tadel Kocjancic

Published 2026-06-25

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CC BY 4.0

Original authors: Ema Kocjancic, Anja Jazbec, Spela Tadel Kocjancic

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine a hospital's Intensive Care Unit (ICU) as a busy emergency repair shop. Usually, when people come in with a "heart engine" failure, the mechanics know exactly what tools to use. But this study looks at a different, messier group of patients: those whose hearts stopped because of something else entirely—like a severe lung infection, a drug overdose, a massive bleed, or a brain injury. The researchers call this "non-cardiac origin" cardiac arrest.

The authors, working at a major hospital in Slovenia, decided to look at their "repair logs" from two different time periods: 2010/2011 and 2022/2023. They wanted to see how the "customers" (patients) and the "repairs" (treatments) had changed over a decade.

Here is the story of what they found, broken down simply:

1. The Customer Base Changed

In the earlier period (2010/2011), most of these patients came from inside the hospital (In-Hospital Cardiac Arrest). By the later period (2022/2023), the mix flipped.

The Shift: More people were now arriving from the street (Out-of-Hospital Cardiac Arrest), and fewer were crashing while already inside the hospital.
The "Why": The authors suggest this might be because doctors inside the hospital got better at spotting sick patients early and fixing them before their hearts stopped. Meanwhile, more people are surviving heart attacks outside the hospital and making it to the ICU, changing the mix of who shows up.
Demographics: The group got slightly more male-dominated, but the average age stayed about the same (around 68 years old).

2. The "First Responders" Got Better

One of the biggest changes happened before the patients even reached the hospital.

The Analogy: Think of bystanders as the "first line of defense." In 2010, only about 23% of people who collapsed outside got immediate help from a passerby. By 2023, that number jumped to 63%.
The Result: This suggests that public education on how to perform CPR is working. More people are stepping up to keep the engine running until the ambulance arrives.

3. The Mechanics Got More Aggressive

When these patients arrived at the ICU in 2023, the doctors were doing much more "detective work" and using more tools than they did in 2010.

More Scans: They were taking far more CT scans (like high-tech X-rays) of the head, chest, and belly to figure out why the heart stopped.
More Time: Patients stayed in the ICU longer. It's like the mechanics decided to keep the car in the shop for a few extra days to make sure every bolt was tight.
More Meds: They used more antibiotics and life-support machines.

4. The Results: A Mixed Bag

Despite the extra effort, better tools, and more bystander help, the final "repair success rate" didn't change much for the whole group.

The Good News: For patients who crashed inside the hospital, survival rates went up significantly (from about 30% to 45%). It seems the hospital team got better at saving the people already under their roof.
The Bad News: For the group as a whole (both inside and outside the hospital), the total number of people who survived to go home did not improve.
The Brain Factor: The number of people who woke up with their brains working well (good neurological outcome) also stayed the same.

The Bottom Line

The study concludes that while the hospital became a more high-tech, aggressive repair shop, and while the public got better at helping before the ambulance arrived, these improvements haven't yet translated into more people walking out of the hospital alive and well.

The authors suggest that for this specific group of patients (whose hearts stopped due to other severe illnesses), the damage is often done before they even reach the hospital door. Even with the best modern tools, if the underlying disease (like a massive infection or organ failure) is too severe, the "engine" might be too broken to fix, regardless of how many scans or extra days in the ICU you add.

In short: We are getting better at finding these patients and trying harder to save them, but the overall success rate remains stubbornly the same, highlighting that this is a very difficult group of patients to treat.

Technical Summary: Out-of-hospital and in-hospital cardiac arrest of non-cardiac origin: a retrospective two-period comparison at a Slovenia tertiary center

Problem Statement
Cardiac arrest of non-cardiac origin represents a heterogeneous group of critically ill patients where the underlying causes (e.g., respiratory failure, sepsis, trauma, intoxication) and management strategies differ significantly from primary cardiac arrest. While cardiac-origin arrest is extensively studied, data regarding temporal changes in the epidemiology, management, and outcomes of non-cardiac-origin cardiac arrest remain limited. The authors sought to address this gap by analyzing whether advances in emergency and intensive care medicine, alongside demographic shifts, have altered the profile and outcomes of this specific patient population over a decade.

Methodology
The study was a retrospective observational cohort conducted at the Center for Intensive Internal Medicine (CIIM) at the University Medical Center Ljubljana, a tertiary referral hospital in Slovenia. The researchers compared two distinct time periods: 2010/2011 and 2022/2023.

Population: The study included 306 consecutive adult patients admitted to the CIIM after successful resuscitation from cardiac arrest of non-cardiac origin. Patients with primary cardiac origin arrest were excluded.
Data Collection: Variables were extracted from the CIIM cardiac arrest registry and electronic medical records. Key data points included patient demographics, arrest location (out-of-hospital [OHCA] vs. in-hospital [IHCA]), witness status, bystander basic life support (BLS), initial rhythm, duration of advanced cardiac life support (ACLS), and diagnostic/treatment interventions (e.g., mechanical ventilation, vasopressors, CT imaging, hemodialysis).
Outcomes: Primary outcomes were the proportion of non-cardiac-origin arrests among all admitted cardiac arrest cases and survival to hospital discharge. Secondary outcomes included neurological status (assessed via Glasgow–Pittsburgh Cerebral Performance Category [CPC] scale), ICU length of stay, and changes in diagnostic intensity.
Statistical Analysis: Categorical variables were compared using chi-square or Fisher's exact tests, while continuous variables were analyzed using Student's t-test or Mann–Whitney U tests, depending on distribution. A p-value < 0.05 was considered statistically significant.

Key Results
The analysis revealed significant shifts in the epidemiology and management of non-cardiac-origin cardiac arrest between the two periods:

Epidemiological Shifts:
- The proportion of admitted cardiac arrest patients classified as non-cardiac origin increased from 35.0% in 2010/2011 to 43.1% in 2022/2023 ( $p=0.021$ ).
- There was a significant shift in arrest location: OHCA increased from 39.9% to 55.4% ( $p=0.007$ ), while IHCA decreased from 60.1% to 44.6% ( $p=0.007$ ).
- The proportion of male patients increased significantly (47.1% vs. 61.3%, $p=0.013$ ), while patient age remained statistically similar.
Prehospital and Diagnostic Changes:
- Bystander CPR for OHCA increased dramatically from 23.1% to 63.1% ( $p<0.001$ ).
- Diagnostic intensity increased significantly in the later period, with higher utilization of head CT ( $p<0.001$ ) and chest/abdominal CT or CT angiography ( $p<0.001$ ).
- Time from emergency call to EMS arrival remained unchanged (approx. 10 minutes).
Treatment and Outcomes:
- ICU Length of Stay: Increased significantly across the cohort (4.1 vs. 5.2 days, $p=0.027$ ).
- IHCA Survival: Survival to discharge for in-hospital non-cardiac-origin arrest improved significantly from 30.1% to 45.3% ( $p=0.048$ ).
- OHCA Survival: Survival for out-of-hospital arrest showed a numerical decrease (40.0% vs. 25.8%) but was not statistically significant ( $p=0.071$ ).
- Overall Survival and Neurology: When analyzing the entire cohort, overall survival (34.1% vs. 34.5%, $p=0.932$ ) and favorable neurological outcomes (CPC 1–2) did not differ significantly between the two periods.

Significance and Claims
The authors conclude that while the landscape of non-cardiac-origin cardiac arrest has shifted toward more out-of-hospital events and involves more extensive diagnostic evaluation and longer ICU stays, these advancements have not yet translated into improved overall survival or favorable neurological outcomes for the heterogeneous population.

The paper posits that the significant improvement in IHCA survival suggests that advances in in-hospital management and earlier recognition are effective for patients arrested within the hospital. However, the lack of improvement in overall outcomes is attributed to the fact that many determinants of survival (particularly in OHCA) occur prior to hospital admission, such as delays in recognition and the severity of underlying non-cardiac diseases. The study highlights that despite improvements in bystander resuscitation and post-arrest care, the "chain of survival" for non-cardiac-origin arrest remains a challenge, necessitating further research into modifiable prehospital factors and targeted interventions for specific subgroups.

Limitations
The authors acknowledge the study's constraints, including its retrospective, single-center design which limits generalizability. The cohort consists only of patients who survived long enough to be admitted to the ICU, potentially excluding the most severe cases. Additionally, missing data in earlier periods and changes in post-arrest care protocols (specifically temperature management and neuroprognostication) may affect the comparability of neurological outcomes.