We aimed to assess the outcomes of cardiogenic shock (CS) complicating acute coronary syndromes (ACS).CS remains the leading cause of mortality in patients presenting with ACS despite advances in care.We studied 13,184 patients undergoing percutaneous coronary intervention (PCI) for all subtypes of ACS enrolled prospectively in a large multicentre Australian registry (Melbourne Interventional Group registry) from 2005 to 2013. All-cause mortality was obtained via linkage to the National Death Index. Patients were divided into those with and those without CS.Compared to the non-CS group (n = 12,548, 95.2%), the CS group (n = 636, 4.8%) had a higher proportion of out-of-hospital cardiac arrest (OHCA) (31.1 vs. 2.2%) and ST-elevation myocardial infarction (STEMI) presentation (89 vs. 34%), both p < .01. Patients in the CS group had higher rates of in-hospital (40.4 vs. 1.2%) and 30-day (41 vs. 1.7%) mortality compared to the non-CS group. Long-term mortality over a median follow-up of 4.2 years was higher in the CS group (50.6 vs. 13.8%), p < .001. Trends of in-hospital and 30-day mortality rates of CS complicating ACS were relatively stable from 2005 to 2013. Predictors of long-term NDI-linked mortality within the CS group include severe left ventricular systolic dysfunction (HR 3.0), glomerular filtration rate (GFR) <30 (HR 2.56), GFR 30-59 (HR 1.94), OHCA (HR 1.46), diabetes (HR 1.44), and age (HR 1.02), all p < .05.Rates of CS-related mortality complicating ACS have remained very high and steady over nearly a decade despite progress in STEMI systems of care, PCI techniques, and medical therapy.