Patients who experience a hospital admission for acute coronary syndromes (ACS) exhibit poor prognosis over the years. The purposes of this study were to evaluate the real-world patterns of out-of-hospital practice in the management of ACS patients and to assess their impact on the risk of selected outcomes. The cohort of 87,530 residents in the Lombardy Region (Italy) who were newly hospitalised for ACS during 2011–2015 was followed until 2018. Exposure to medical treatment including use of selected drugs, diagnostic procedures and laboratory tests was recorded. The main outcome of interest was re-hospitalisation for cardiovascular (CV) outcomes. Proportional hazards models were fitted to estimate hazard ratio, and 95% confidence intervals (CI), for the exposure-outcome association. Analyses were stratified according to the ACS type. The cumulative incidence of re-hospitalisation for CV disease was 33%, 42% and 38% at 5 years after index discharge among STEMI, NSTEMI and unstable angina patients. Within one year from index discharge, between 70% and 80% of patients had at least a prescription of statins, beta-blockers and renin–angiotensin-system blocking agents, underwent ECG and lipid profile examination, and had a cardiologic examination. One patient in five underwent cardiac rehabilitation. Compared with patients who did not adhere to healthcare recommendations, the risk of CV hospital readmission was reduced from 10% (95% CI: 4%–10%) to 23% (12%–32%) among patients who underwent lipid profile examinations and who experienced cardiac rehabilitation. Close out-of-hospital healthcare must be considered the cornerstone for improving the long-term prognosis of ACS patients. •The risk of CV disease was 37% at 5 years since index discharge for ACS.•80% of patients used selected drugs, underwent ECG and lipid profile examination.•One patient on five underwent cardiac rehabilitation.•Cardiovascular risk was affected by adherence to recommendations.