BACKGROUND: Few studies describe recent changes in the incidence, treatment, and outcomes of cardiogenic shock. OBJECTIVE: To examine temporal trends in the incidence, therapeutic management, and mortality rates of patients with the acute coronary syndrome (ACS) and cardiogenic shock, and to assess associations of therapeutic management with death and cardiogenic shock developing during hospitalization. DESIGN: Analysis of registry data collected among patients admitted to hospitals between 1997 and 2006. SETTING: 70 of the 106 acute cardiac care hospitals in Switzerland. PATIENTS: 23 696 adults with ACS enrolled in the AMIS (Acute Myocardial Infarction in Switzerland) Plus Registry. MEASUREMENTS: Cardiogenic shock incidence; treatment, including rates of percutaneous coronary intervention; and in-hospital mortality rates. RESULTS: Rates of overall cardiogenic shock (8.3% of patients with ACS) and cardiogenic shock developing during hospitalization (6.0% of patients with ACS and 71.5% of patients with cardiogenic shock) decreased during the past decade (P < 0.001 for temporal trend), whereas rates of cardiogenic shock on admission remained constant (2.3% of patients with ACS and 28.5% of patients with cardiogenic shock). Rates of percutaneous coronary intervention increased among patients with cardiogenic shock (7.6% to 65.9%; P = 0.010), whereas in-hospital mortality decreased (62.8% to 47.7%; P = 0.010). Percutaneous coronary intervention was independently associated with lower risk for both in-hospital mortality in all patients with ACS (odds ratio, 0.47 [95% CI, 0.30 to 0.73]; P = 0.001) and cardiogenic shock development during hospitalization in patients with ACS but without cardiogenic shock on admission (odds ratio, 0.59 [CI, 0.39 to 0.89]; P = 0.012). LIMITATIONS: There was no central review of cardiogenic shock diagnoses, and follow-up duration was confined to the hospital stay. Unmeasured or inaccurately measured characteristics may have confounded observed associations of treatment with outcomes. CONCLUSION: Over the past decade, rates of cardiogenic shock developing during hospitalization and in-hospital mortality decreased among patients with ACS. Increased percutaneous coronary intervention rates were associated with decreased mortality among patients with cardiogenic shock and with decreased development of cardiogenic shock during hospitalization.