Background. - Historical cohorts have shown extent of coronary artery disease to be a predictor of poorer outcomes in ST-segment elevation myocardial infarction. However, contemporary data in the era of reperfusion and modern secondary prevention therapy are lacking.Aim. - To compare 3-year survival in patients with ST-segment elevation myocardial infarction with multivessel disease versus those with single-vessel disease.Methods. - Using data from the FAST-MI 2005, 2010 and 2015 registries, three nationwide French surveys, we included all patients with ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention within 24 hours of symptom onset. Baseline characteristics, management and 3-year all-cause mortality were analysed according to coronary status (single-, two- and three-vessel disease).Results. - Among 3907 patients (mean age 62.4 +/- 13.7 years; 75.9% male), patients with multivessel disease (two- or three-vessel disease) accounted for 47.9%; overall, they were older, with higher cardiovascular risk profiles. In a multivariable adjusted Cox proportional hazard regression model, only patients with three-vessel disease had a higher rate of mortality at 3 years compared with those with single-vessel disease (hazard ratio 1.52, 95% confidence interval 1.68-2.26; P < 0.001). Finally, patients with multivessel disease with complete myocardial revascularization before discharge had a similar prognosis to patients with single-vessel disease (hazard ratio 1.17, 95% confidence interval 0.84-1.64; P = 0.35).Conclusions. - Multivessel disease still represents an important proportion of patients with ST-segment elevation myocardial infarction. Although three-vessel disease is associated with higher 3-year mortality, patients with multivessel disease and complete myocardial revascularization in the contemporary era have a 3-year risk of death similar to that in patients with single-vessel disease.