Performance of 0/1 h versus 0/3 h pathways in patients with suspected myocardial infarction: a systematic review and individual participant data meta-analysis of randomised controlled trials.

In patients with suspected myocardial infarction, the 0/1 h pathway (blood draws at 0 h and 1 h) is recommended in current guidelines for early risk stratification. However, individual trials used different safety outcomes, and efficacy outcomes were inconclusive or not assessed. We conducted a systematic review and individual participant data meta-analysis of all randomised controlled trials to synthesise the totality of the evidence, assess heterogeneity across trials, and evaluate clinically relevant outcomes using harmonised definitions across trials. In this systematic review and individual participant data meta-analysis, we searched PubMed, Cochrane Central Register of Controlled Trials, Scopus, and the International Clinical Trials Registry Platform from inception to July 6, 2026, without language restrictions, for randomised trials comparing the safety and efficacy of 0/1 h versus 0/3 h pathways (blood draws at 0 h and 3 h, ie, standard care). Individual participant data were obtained and outcome definitions were harmonised. The primary analysis used a two-stage random-effects meta-analysis. After receipt of the individual participant data but before data harmonisation or analysis, the primary safety outcome was refined to a composite of all-cause death or new type 1 myocardial infarction within 30 days, from the originally specified composite of all-cause death or any new myocardial infarction. The primary efficacy outcomes were emergency department length of stay and direct discharge from the emergency department. This meta-analysis is registered with PROSPERO (CRD420261383452). Our systematic review identified five randomised trials, all of which provided individual participant data. Among these, the definition of the primary safety outcome varied, and in four trials emergency department length of stay was not reported for the whole analysis population. We included 110 933 patient presentations (55 489 managed with the 0/1 h pathway and 55 444 managed with the 0/3 h pathway). Within 30 days, all-cause death or new type 1 myocardial infarction occurred in 446 patient presentations (0·8%) with the 0/1 h pathway versus 562 patient presentations (1·0%) with the 0/3 h pathway (random-effects pooled odds ratio [OR] 0·83 [95% CI 0·45-1·53]; I 2 =62·9%; τ 2 =0·143). Emergency department length of stay was 314 min (IQR 211-481) in the 0/1 h pathway group versus 308 min (209-453) in the 0/3 h pathway group (random-effects pooled geometric mean ratio 1·03 [95% CI 0·85-1·25]; I 2 =99·2%; τ 2 =0·024). Direct discharge from the emergency department occurred in 37 190 patient presentations (67·0%) with the 0/1 h pathway versus 36 485 patient presentations (65·8%) with the 0/3 h pathway (random-effects pooled OR 1·31 [95% CI 0·79-2·16]; I 2 =97·8%; τ 2 =0·156). Across the available randomised trials, short-term adverse event rates were low with both pathways, but the pooled safety estimate remained imprecise. On average, earlier cardiac troponin retesting did not reduce emergency department length of stay or clearly increase direct discharge, and substantial between-study heterogeneity indicates that treatment effects might not translate uniformly across health-care systems. For hospitals considering transitioning from a 0/3 h to a 0/1 h pathway, implementation decisions should take broader diagnostic and organisational considerations into account. Swiss National Science Foundation, Swiss Heart Foundation, University Hospital Basel, University of Basel, and Foundation for Cardiovascular Research Basel.