Most OHCA Survivors Maintain or Improve Function Two Years After Cardiac Arrest

Out-of-hospital cardiac arrest (OHCA) is a leading cause of death and disability globally. In New Zealand, roughly 2,547 adult cardiac arrest events occur annually where resuscitation is attempted, with only about 11% surviving to 30 days. For those who survive, neurological impairment ranging from mild cognitive deficits to severe disability is common, yet data on longer-term outcomes beyond 6 months remain scarce. This study was designed to fill that gap by characterizing the 24-month neurological, functional, and health-related quality of life trajectory of OHCA survivors.

Researchers conducted a preplanned prospective longitudinal cohort study of all 200 New Zealand participants enrolled in the international TAME (Targeted Therapeutic Mild Hypercapnia after resuscitated Cardiac Arrest) trial. Participants were adults aged ≥18 years who achieved sustained return of spontaneous circulation (ROSC) after OHCA and were admitted to an ICU. The cohort was predominantly male (79%), with a mean age of 56.7 years. Most arrests were witnessed (88%), received bystander CPR (88%), and had an initial shockable rhythm of ventricular fibrillation (72.5%). Outcomes were assessed at both 6 and 24 months using the Glasgow Outcome Scale-Extended (GOSE), modified Rankin Scale (mRS), EQ-5D-5L, Montreal Cognitive Assessment-Blind (MoCA-Blind), IQCODE, and Symbol Digit Modalities Test (SDMT).

Of 200 enrolled participants, 194 (97%) had 24-month data available. Consistent with the overall TAME trial finding, there was no statistically significant difference in favourable neurological outcome between the targeted mild hypercapnia and normocapnia groups at 24 months (52.9% vs. 54.5%; RR 0.97, 95% CI 0.67–1.40). When the cohort was analysed as a whole, 56.3% achieved a favourable neurological outcome (GOSE 5–8) at 6 months. Crucially, functional and health-related quality of life status at 24 months was not worse than at 6 months for the majority of survivors, and very few participants reported more than slight disability. This suggests that for those who survive to 6 months in reasonable condition, further deterioration is uncommon and continued improvement is possible.

These findings carry important implications for patient and family counselling, goals-of-care discussions, and healthcare resource planning. The stability or improvement in outcomes between 6 and 24 months suggests that the 6-month timepoint — commonly used as an endpoint in cardiac arrest trials — may not fully capture the complete recovery arc. Clinicians and families can be informed that recovery does not plateau at 6 months and that ongoing improvement is realistic for many survivors.

Several caveats temper these conclusions. The study is a sub-group analysis of a clinical trial and was not independently powered for 24-month treatment comparisons. The cohort is relatively small (N=200) and reflects New Zealand's specific demographics and healthcare system, limiting generalisability. Additionally, planned Australian recruitment did not proceed due to funding constraints, further narrowing the sample. Nonetheless, the 97% data retention rate at 24 months and use of multiple validated outcome instruments strengthen confidence in the findings.