Older age is associated with worse outcomes in patients with cardiogenic shock complicating ST-elevation myocardial infarction (STEMI). However, significant heterogeneity exists in different age groups with respect to outcomes. Identification of factors that modulate age-related risk of death in patients with cardiogenic shock may help clinical decision making and facilitate patient counseling. Accordingly, we evaluated 761 patients with STEMI who presented with cardiogenic shock and received fibrinolysis. We categorized patients into 3 age groups (<60 years, n = 224; 60 to 75 years, n = 360; and > or = 75 years, n = 177). Death at 30 days occurred in 118 patients <60 years of age (53%), 214 patients 60 to 75 years of age (59%), and 127 patients > or = 75 years of age (72%) with cardiogenic shock. Factors associated with death (per 10-U change) on multivariable analysis were older age (odds ratio [OR] 1.43, 95% confidence interval [CI] 1.23 to 1.66), higher heart rate (OR 1.27, 95% CI 1.19 to 1.35), and lower systolic blood pressure (OR 1.32, 95% CI 1.23 to 1.41, c index 0.79). Important interactions were found with age, heart rate, and systolic blood pressure, suggesting that, although age was a strong independent predictor of death in patients with a heart rate < or = 100 beats/min, it was less strongly related to death in patients with a heart rate >100 beats/min in whom prognosis was uniformly poor. Further, elderly patients with a systolic blood pressure >80 mm Hg had substantial chance of recovery. In contrast, those with a systolic blood pressure < or = 80 mm Hg and heart rate >100 beats/min had 30-day death rates >90% even if they were young. In conclusion, our data suggest that, although elderly patients with cardiogenic shock have poor prognosis, presenting heart rate and systolic blood pressure provide important information to differentiate who may have greater chance of recovery. This information may help physicians in deciding treatment options for patients with cardiogenic shock and counseling them about their risks.