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Characteristics of Out-of-Hospital Cardiac Arrest Patients With STEMI: A Retrospective Observational Study From New Zealand

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Thesis under embargo until 12th August 2026(1.6 MB)

Date

2025

Authors

Supervisor

Todd, Verity
Howie, Graham
Dicker, Bridget

Item type

Thesis

Degree name

Master of Philosophy

Journal Title

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Volume Title

Publisher

Auckland University of Technology

Abstract

Coronary artery occlusions often lead to out-of-hospital cardiac arrest (OHCA). ST-elevation myocardial infarction (STEMI), a type of occlusion, is treated with reperfusion therapy, typically fibrinolysis. Approximately 10% of STEMI cases progress to OHCA. Concurrently, Aotearoa New Zealand (AoNZ) experiences nearly 6,000 OHCA incidents annually, with about half receiving resuscitation attempts. Despite comparable international survival rates, there is a need to improve OHCA mortality. This thesis was born with our hypothesis that intra-OHCA fibrinolysis could benefit patients with both STEMI and OHCA by resolving the occlusion. To test this hypothesis, we have authored both a systematic literature review and a retrospective cohort analysis focusing on the possible association between STEMI and OHCA and their treatment. We examined the benefit or otherwise of applying STEMI treatment (fibrinolysis) to OHCA, working with sparse and ambivalent existing literature. We endeavoured to identify the proportion of OHCA patients with concurrent STEMI and/or cardiac chest pain within AoNZ, and describe fibrinolysis rates and characteristics in these patients. Seventeen articles met our inclusion criteria. We have developed a new way of categorising OHCA literature based on fibrinolysis timing: pre-OHCA (1 article), intra-OHCA (6 articles), post-OHCA (4 articles), and not documented (6 articles). Most articles reported on mortality. No mortality benefit was found for pre- or intra-OHCA fibrinolysis. Some improvement was seen with post-OHCA fibrinolysis, though positive prognostic factors confounded this. Our retrospective cohort analysis found that, from January 2020 to December 2022, 725 patients in AoNZ had both OHCA and STEMI and/or cardiac chest pain; and 12.7% (n=92) received fibrinolysis. The median patient was 66 years old, non-Māori, and urban-dwelling. Most incidents occurred at home. No significant differences in age, sex, ethnicity, or deprivation were found between those receiving and not receiving fibrinolysis (p>0.05). Rural patients were more likely to receive fibrinolysis (50.0%, n=46) compared to urban patients (19.6%, n=124; p<0.05), with rural patients having 3.87 times higher odds of receiving fibrinolysis (aOR 3.87, 95%CI 2.42-6.19, p<0.001). Our research has shown that the current literature on fibrinolysis in OHCA is mixed and sparse. Treatment-specific mortality rates are confounded by other positive prognostic factors, making it difficult to determine the clear benefits, if any, of fibrinolysis during OHCA. Such factors are difficult to isolate in an OHCA setting. We can confirm that fibrinolysis is administered equitably in AoNZ, with rural patients more likely to receive it. We have found that fibrinolysis may be beneficial in the post-OHCA phase, but we believe that further research with larger sample sizes and controlled variables is required. The impact of fibrinolysis on survival remains uncertain due to significant confounding factors. Future research should aim to control these factors to assess fibrinolysis’ impact on OHCA mortality accurately.

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http://hdl.handle.net/10292/19663

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