The European Society of Cardiology (ESC) recommends 0/1h-algorithms for triage of patients with suspected myocardial infarction (MI). Recently, cut-offs allowing 3h triage using high-sensitivity cardiac troponin T (hs-cTnT) have been derived, but their prognostic implications remain unclear, and external validation is lacking. To externally validate the diagnostic performance and assess the prognostic impact of the 0/1/3h algorithm for cardiovascular events in an all-comer cohort with suspected MI. We prospectively enrolled patients presenting to the emergency department with suspected MI. hs-cTnT was measured at presentation, 1h, and 3h. Patients were followed up to evaluate all-cause mortality and major adverse cardiovascular events (MACE). Diagnostic accuracy was assessed by stratifying patients using the 0/1/3h algorithm. Cox regression analyses compared cardiovascular risk at 90 days and three years between rule-in and rule-out groups. Among 2,514 patients (median age 64 years; 63.6% men), the algorithm demonstrated excellent rule-out safety (sensitivity 98.6% [95% CI, 96.8, 99.4]; NPV 99.7% [99.2, 99.9]) and moderate rule-in capacity (specificity 89.3% [87.9, 90.5]; PPV 60.8% [56.8, 64.7]). Over three years, 646 patients experienced MACE, and 256 died (68 cardiac deaths). Patients ruled-out at 3h had doubled MACE risk (HR 2.11 [1.44, 3.08]) and quadrupled mortality risk (HR 4.33 [1.85, 10.12]) compared to immediate rule-out (p<0.001). The 0/1/3h algorithm shows excellent diagnostic safety and adds prognostic value, with delayed rule-out associated with significantly increased long-term cardiovascular risk and mortality.