This retrospective, exploratory cross-sectional study was conducted at SAGH, which is the primary referral center for cardiac emergencies in the region. The hospital is equipped with an emergency department (ED), intensive care unit (ICU), and a cardiac catheterization laboratory. Data were drawn from the Pan-Asian Resuscitation Outcomes Study (PAROS) OHCA registry, an international research collaboration designed to improve outcomes for OHCA patients across Asia.

The study included all adult OHCA patients (aged ≥18 years) treated in the ED of SAGH from June 2015 to May 2023. Patients were included if they had a cardiac arrest outside of the hospital and were subsequently brought to SAGH for emergency management. The following exclusion criteria were applied: (1) traumatic cardiac arrest; (2) pediatric patients (<18 years); (3) confirmed coronavirus disease 2019 (COVID-19) infection; and (4) patients who were dead on arrival or experienced cardiac arrest after hospital admission.

Data were obtained from the PAROS OHCA registry, which prospectively collects comprehensive records of OHCA cases using the internationally standardized Utstein-style template. Key variables included: (1) demographic variables—age, sex, and comorbid conditions (e.g., heart disease, diabetes, hypertension); (2) arrest characteristics—location of arrest, initial rhythm (shockable vs. non-shockable), interval from collapse to CPR, and time to hospital arrival; (3) in-hospital interventions—use of advanced airway management (either endotracheal intubation or supraglottic airway devices), defibrillation, administration of resuscitation medications (e.g., epinephrine), targeted temperature management (TTM), and PCI; (4) outcome variable—survival to admission, defined as survival to transfer to intensive care or survival for at least 8 hours in the ED.

All analyses were performed using IBM SPSS Statistics version 25.0. Continuous variables were expressed as medians with interquartile ranges (IQR) due to non-normal distribution, while categorical variables were reported as frequencies and percentages. The Mann–Whitney U test was used for comparisons of continuous variables, and the chi-square test for categorical variables. Variables with a P-value <0.25 in bivariate analyses were entered into a multivariable logistic regression model to identify independent predictors of survival to admission. Results were expressed as adjusted odds ratios (OR) with 95% confidence intervals (CIs). A P-value <0.05 was considered statistically significant.

This study was approved by the Institutional Review Board of Saiful Anwar General Hospital, Malang (No. 400/140/K.3/102.7/2023). The need for informed consent was waived due to the retrospective study design and the use of anonymized patient data.

During the study period from June 2015 to May 2023, a total of 511 OHCA cases were documented in the PAROS registry at SAGH, Malang, Indonesia. After applying the exclusion criteria—which included patients younger than 18 years, trauma-related cardiac arrests, and those declared dead on arrival—83 cases were excluded from the analysis. This left 428 eligible cases for final cross-sectional evaluation. Among these, 121 patients (28.27%) achieved ROSC, 31 patients (7.24%) survived to admission, and 10 patients (2.33%) were eventually discharged. Survival to admission was defined as either transfer to the ICU or survival for at least 8 hours in the ED following resuscitation (Fig. 1).

The baseline characteristics for the 428 eligible OHCA cases are summarized in Table 1. The mean age of the study population was 55.7 years, with a median age of 57 years (IQR, 48–66 years), reflecting a wide age distribution among patients. Most patients were male, accounting for 67.8% (n=290) of the cohort. The three most common comorbidities were hypertension (35.7%, n=153), heart disease (28.3%, n=121), and diabetes mellitus (23.4%, n=100). These conditions are known to negatively affect cardiovascular health and may increase susceptibility to cardiac arrest, as well as contribute to poorer outcomes following resuscitation.

The initial cardiac rhythm was predominantly non-shockable, identified in 423 patients (98.8%), typically manifesting as asystole or pulseless electrical activity. Shockable rhythms, such as ventricular fibrillation or pulseless ventricular tachycardia, were rare and observed in only five patients (1.2%). The median time from cardiac arrest to initiation of CPR was 15 minutes (IQR, 10–20 minutes), and the median time to hospital arrival was 30 minutes (IQR, 22–37 minutes). This considerable delay in-hospital arrival likely influenced the initial success of resuscitation and overall outcomes.

Among the 31 patients who survived to admission, 23 (5.4%) were male, suggesting a potential gender disparity in survival. The median age of survivors was 54 years (IQR, 45–64 years), slightly lower than the overall cohort, which may indicate better outcomes among younger patients with OHCA. Notably, all 31 survivors received advanced airway management, emphasizing the vital role of securing the airway and ensuring effective ventilation in the stabilization of OHCA patients. Defibrillation was performed in eight patients, with three survivors (0.7%), underscoring the critical importance of prompt defibrillation for those with shockable rhythms (Table 1).

Three patients (0.7%) underwent PCI, suggesting that revascularization can improve survival to admission, even in a resource-limited setting. However, the overall low rates of PCI and defibrillation reflect limitations in the availability and application of advanced cardiac interventions, which could be targeted for future quality improvement initiatives.

Bivariate analysis (Table 2) identified several significant individual predictors of survival. These included the time of arrest (P=0.014), defibrillation (OR, 8.400; 95% CI, 1.909–36.968; P=0.015), advanced airway management (OR, 12.592; 95% CI, 3.765–42.107; P=0.000), and PCI (OR, 27.310; 95% CI, 2.405–310.180; P=0.015), all of which were significantly associated with survival to admission.

Multivariable logistic regression analysis (Table 3) revealed several independent predictors of survival to admission among the study population. Advanced airway management emerged as a crucial factor, with patients who received this intervention being significantly more likely to survive to admission (OR, 13.286; 95% CI, 3.928–44.937; P<0.001). This highlights the essential role of early airway management and adequate ventilation during the initial hours post-resuscitation—core components of advanced life support that are linked to improved outcomes in OHCA.

Furthermore, PCI was found to be a significant independent predictor, with survival odds to admission being 13 times higher for patients who underwent PCI than those who did not (OR, 13.307; 95% CI, 1.089–162.635; P=0.043). This result underscores the importance of rapid revascularization in selected OHCA patients and supports integrating PCI-capable hospitals into regional cardiac arrest care systems, even in resource-constrained environments.

Conversely, hypertension was negatively associated with survival to admission (OR, 0.369; 95% CI, 0.149–0.912; P=0.031), indicating that patients with hypertension may have an elevated risk of poor outcomes post-cardiac arrest, likely due to preexisting cardiovascular and end-organ damage that can reduce the effectiveness of resuscitation.

This study has several limitations that should be considered when interpreting the results. A major limitation is the exclusion of pre-hospital data, such as time to first CPR, EMS response times, and pre-hospital interventions like defibrillation and airway management. These variables are crucial for understanding survival determinants in OHCA, as timely interventions greatly affect outcomes. Without this information, our analysis may not fully capture the complexity of patient care. Additionally, the relatively small sample size limits the generalizability of our findings and may weaken statistical power. Larger studies would provide more robust insights into the influence of in-hospital factors on survival. Future research should include both pre-hospital and in-hospital data to offer a more comprehensive evaluation.

Our database also lacked detailed in-hospital medication records, including the use of advanced life support drugs, which are important for accurate risk adjustment in multivariable analysis. It is important to note that patients who undergo advanced airway management are typically those who survive to hospital arrival and are considered candidates for continued resuscitation, whereas those who are already deceased or for whom airway management is not feasible are excluded. This may introduce bias, as advanced airway management is not performed in all cases. Furthermore, the timing of both advanced airway management and PCI was not recorded, limiting our ability to assess the optimal timing for these interventions. The absence of TTM and the small number of patients undergoing PCI further restrict the generalizability of our findings regarding these interventions. Future studies should address these gaps to provide a more nuanced understanding of the factors influencing OHCA outcomes.

This study identified advanced airway management and cardiac catheterization as significant independent predictors of survival to admission among OHCA patients treated in a resource-limited setting. Although defibrillation was associated with improved survival in bivariate analysis, it did not emerge as an independent predictor in multivariable analysis. These findings highlight the importance of timely and effective in-hospital interventions—particularly advanced airway management and PCI—in improving patient outcomes. The negative association of hypertension with survival further emphasizes the need for comprehensive strategies targeting comorbid conditions. Optimizing emergency care protocols and addressing these key factors have the potential to enhance survival outcomes for OHCA patients in similar healthcare settings.