Out-of-hospital cardiac arrest (OHCA) remains associated with poor outcomes despite advances in care. Coronary artery disease is the leading cause, yet the prognostic role of initial coronary flow status, assessed by Thrombolysis In Myocardial Infarction (TIMI) grade at angiography, has not been fully explored in OHCA survivors.

To evaluate the prognostic impact of preprocedural TIMI flow in this population, and to identify predictive factors for reduced TIMI flow.

We analysed data from the prospective PROCAT registry, including consecutive patients with OHCA with no extracardiac cause who underwent early coronary angiography between May 2016 and August 2022 at Cochin Hospital, Paris. Patients were categorized into three groups: non-ischaemic OHCA (OHCAni); ischaemic OHCA with preserved flow (TIMI 2–3; OHCAi2–3); and ischaemic OHCA with reduced flow (TIMI 0–1; OHCAi0–1). The primary endpoint was 1-year death; secondary endpoints included in-hospital death, neurological outcome at discharge and major bleeding (Bleeding Academic Research Consortium types 3–5).

Among 330 patients, 181 (55%) had OHCAni, 58 (18%) had OHCAi2–3 and 91 (27%) had OHCAi0–1. The 1-year death rate was significantly higher in the OHCAni group (66.7%) than in the ischaemic OHCA groups (OHCAi2–3, 34.5%; OHCAi0–1, 36.7%; P < 0.001). Favourable neurological outcome (Cerebral Performance Category 1–2) at hospital discharge was observed in 64.4% of the OHCAni group versus 64.9% and 58.9% in the OHCAi2–3 and OHCAi0–1 groups, respectively ( P < 0.001). Major bleeding was more frequent in the OHCAi2–3 group (28.1%) than the OHCAi0–1 group (11.5%; P = 0.02). In multivariable analysis restricted to ischaemic OHCA, reduced TIMI flow independently predicted 1-year death (odds ratio 2.58, 95% confidence interval 1.02–7.22; P = 0.05), along with older age, longer low-flow duration and absence of shockable rhythm.

Ischaemic and non-ischaemic OHCA represent distinct clinical entities, with markedly poorer outcomes in the non-ischaemic group. In ischaemic OHCA, reduced preprocedural TIMI flow is an independent predictor of 1-year death despite high procedural success rates. Early assessment of coronary flow may thus provide important prognostic information, and should be integrated into risk stratification models for OHCA survivors.